EPIDEMIOLOGY

Spectrum of BRCA1/2 point mutations and genomicrearrangements in high-risk breast/ovariancancer Chilean families

Patricio Gonzalez-Hormazabal • Sara Gutierrez-Enriquez • Daniel Gaete •

Jose M. Reyes • Octavio Peralta • Enrique Waugh • Fernando Gomez •

Sonia Margarit • Teresa Bravo • Rafael Blanco • Orland Diez • Lilian Jara

Received: 13 July 2010 / Accepted: 6 September 2010 / Published online: 22 September 2010

� Springer Science+Business Media, LLC. 2010

Abstract The distribution of BRCA1/2 germline mutations

in breast/ovarian cancer (BC/OC) families varies among

different populations. In the Chilean population, there are

only two reports of mutation analysis of BRCA1/2, and these

included a low number of BC and/or OC patients. Moreover,

the prevalence of BRCA1/2 genomic rearrangements in

Chilean and in other South American populations is

unknown. In this article, we present the mutation-detection

data corresponding to a set of 326 high-risk families ana-

lyzed by conformation-sensitive gel electrophoresis and

heteroduplex analysis. To determine the contribution of

BRCA1/2 LGRs in Chilean BC patients, we analyzed 56

high-risk subjects with no pathogenic BRCA1/2 point

mutations. Germline BRCA1/2 point mutations were found

in 23 (7.1%) of the 326 Chilean families. Families which had

at least three BC and/or OC cases showed the highest fre-

quency of mutations (15.9%). We identified 14 point

pathogenic mutations. Three recurrent mutations in BRCA1

(c.187_188delAG, c.2605_2606delTT, and c.3450_3453

delCAAG) and three in BRCA2 (c.4969_4970insTG,

c.5374_5377delTATG, and c.6503_6504delTT) contributed

to 63.6 and 66.7% of all the deleterious mutations of each

gene, which may reflect the presence of region-specific

founder effects. Taken together BRCA1/2 recurrent point

mutations account for 65.2% (15/23) of the BRCA1/2 (?)

families. No large deletions or duplications involving

BRCA1/2 were identified in a subgroup of 56 index cases

negative for BRCA1/2 point mutations. Our study, which is

the largest conducted to date in a South American popula-

tion, provides a comprehensive analysis on the type and

distribution of BRCA1/2 mutations and allelic variants.

Keywords Breast cancer � BRCA1/2 �Chilean population � LGRs � Recurrent mutations

Orland Diez and Lilian Jara contributed equally to this study.

P. Gonzalez-Hormazabal � D. Gaete � R. Blanco � L. Jara (&)

Human Genetics Program, Institute of Biomedical Sciences

(ICBM), School of Medicine, University of Chile,

Av. Independencia 1027, P.O. Box 70061, Santiago, Chile

e-mail: ljara@med.uchile.cl

S. Gutierrez-Enriquez � O. Diez

Vall d’Hebron Institute of Oncology (VHIO), Barcelona, Spain

S. Gutierrez-Enriquez

Medical Oncology Program, Vall d’Hebron University

Hospital Research Institute, Barcelona, Spain

J. M. Reyes � O. Peralta

Clınica Las Condes, Santiago, Chile

O. Peralta

Department of Ginaecology and Obstetrics, School of Medicine,

University of Chile, Av Santa Rosa 1234, Santiago, Chile

E. Waugh � F. Gomez

Clınica Santa Marıa, Santiago, Chile

S. Margarit

School of Medicine and Clınica Alemana, Universidad

del Desarrollo, Santiago, Chile

T. Bravo

National Cancer Society (Corporacion Nacional del

Cancer—CONAC), Santiago, Chile

O. Diez (&)

Oncogenetics Laboratory, Molecular Medicine and Genetics

Program, University Hospital Vall d’Hebron, Passeig Vall

d’Hebron 119-129, 08035 Barcelona, Spain

e-mail: odiez@vhebron.net

123

Breast Cancer Res Treat (2011) 126:705–716

DOI 10.1007/s10549-010-1170-y

Introduction

Breast cancer (BC) is the most common cancer among

women worldwide. It has been established that one out of

eight women will develop BC during their lives [1]. In

Chile, mortality in women due to BC has risen, from 8.5

deaths per 100,000 women in 1985 to 12.8 per 100,000

women in 1995 [2]. Currently, it has the second-highest

mortality rate among cancers (13.8/100,000 women) [3].

Incidence increased from 16.2/100,000 women in 1998 to

26.2/100,000 women in 2002 [4].

Hereditary BC accounts for 5–15% of all the BC cases

[5]. Together, germline mutations in the two major sus-

ceptibility genes BRCA1 and BRCA2 (BRCA1/2) account

for approximately 20% of familial BC cases [6]. Carriers of

mutations in any of these genes have a 40–85% cumulative

lifetime risk of BC by the age of 70. Studies of BRCA1/2

mutation frequencies have revealed significant differences

in populations of different geographic regions and ethnic-

ities. Disease-causing mutations are distributed throughout

the entire coding regions of both genes. Since the identi-

fication of BRCA1 and BRCA2 as the principal genes

responsible for inherited BC [7, 8], more than 3,400 dis-

tinct DNA sequence variants have been described in the

BIC database (http://research.nhgri.nih.gov/bic/), of which

1,625 can be classified as pathogenic, including 1,454

truncating mutations (1,075 frameshift and 379 nonsense)

and 139 splicing alterations. The remaining mutations,

including 1,351 distinct missense changes, are unclassified

variants of uncertain clinical consequences. In addition to

point mutations that can be detected within a PCR frag-

ment, BRCA1 and BRCA2 are both known to have germline

mutations resulting from Large Genomic Rearrangements

(LGRs) that result in duplications or deletions of one or

more exons, usually producing premature stop codons.

Little is known about the contribution of BRCA1/2 to

hereditary BC in South American populations. In the

Chilean population, there are only two reports of mutation

analysis of BRCA1/2, and these included a low number of

BC and/or ovarian cancer (OC) patients [9, 10]. Moreover,

the prevalence of BRCA1/2 genomic rearrangements in

Chilean and in other South American populations is

unknown. In this article, we present the mutation-detection

data corresponding to a set of 326 high-risk families ana-

lyzed by conformation-sensitive gel electrophoresis and

heteroduplex analysis. Results of 64 out of these 326 high-

risk families were previously reported [9] showing that the

BRCA1/2 gene mutation spectrum was heterogeneous and

broad. Our current study, which is the largest conducted to

date in a South American population, provides a compre-

hensive analysis on the type and distribution of BRCA1/2

mutations and allelic variants. To determine the contribu-

tion of BRCA1/2 LGRs in Chilean BC patients, we

analyzed 56 high-risk subjects with no pathogenic BRCA1/

2 point mutations.

Methods

Families

In this study, 326 high-risk BC/OC Chilean families were

selected from the files of the Servicio de Salud del Area

Metropolitana de Santiago, Corporacion Nacional del

Cancer (CONAC) and other private services in the

Metropolitan Area of Santiago. Pedigrees were constructed

on the basis of an index case considered to have the highest

probability of being a deleterious mutation carrier. None of

the families met the strict criteria for other known syn-

dromes involving BC, such as Li-Fraumeni, ataxia-telan-

giectasia, or Cowden disease. All the families participating

in the study self reported Chilean ancestry dating several

generations, after extensive interviews with several mem-

bers of each family from different generations.

Table 1 shows the specific characteristic of the families

selected according to the inclusion criteria. In the sample of

selected families, 15.3% (50/326) had bilateral BC, 9.0%

(29/326) had BC and OC, and 2.8% (9/326) presented male

BC. From the 326 families which participated in this study,

348 women had only BC, 2 had both BC and OC, 5 had

OC, and 7 had male BC. BC and OC for all the cases

included in the study were verified using the original

pathology report.

This study was approved by the Institutional Review

Board of the School of Medicine of the University of

Chile. Informed consent was obtained from all the

participants.

Table 1 Inclusion criteria for the families included in this study

Group Inclusion criteria Families

N (%)

A Three or more family members with breast

and/or ovarian cancer

88 (27.0)

B Two family members with breast cancer 106 (32.5)

C One family member with breast cancer and

one with ovarian cancer

9 (3.4)

D Single affected individual with breast cancer

Bage 35

57 (17.5)

E Single affected individual with breast cancer

Bage 50

60 (18.0)

F Single affected individual with male breast

cancer

6 (1.8)

Total 326 (100)

706 Breast Cancer Res Treat (2011) 126:705–716

123

BRCA1 and BRCA2 mutation analysis

Genomic DNA was extracted from peripheral blood lym-

phocytes of 362 index cases belonging to the 326 high-risk

selected families. Samples were obtained according to the

method described by Chomczynski and Sacchi [11].

The whole coding sequences and exon–intron bound-

aries of the BRCA1 and BRCA2 genes were analyzed for

sequence variants using conformational-sensitive gel elec-

trophoresis according to described protocols [9]. Any

fragment showing a mobility shift was directly sequenced

in both directions. Sequencing was performed in an ABI

prism 3100 automated fluorescence-based cycle sequencer

(Applied Biosystems, USA) and a rhodamine dye termi-

nator system (Applied Biosystems, USA).

Multiplex Ligation-Dependent probe Assay (MLPA) was

performed for screening LGRs in a subgroup of 56 index cases

negative for BRCA1/2 point mutations. MLPA analysis was

performed according to manufacturer instructions (MRC

Holland, Holland) using the SALSA MLPA Kit P002-B1 for

BRCA1 and SALSA MLPA Kit P045-B1 for BRCA2. The

fragments obtained were analyzed by capillary electrophore-

sis using an ABI3130-xl Genetic Analyzer (Applied Biosys-

tems, USA) with a 36-cm capillary array and POP-7 polymer

(Applied Biosystems, USA). GeneMapper 4.0 software

(Applied Biosystems, USA) was used for fragment analysis,

and the results (peak size, height, and areas) were exported to

an Excel data sheet to calculate the relative peak area. Nor-

malization was achieved by dividing the intra-normalized

peak area by the average intra-normalized probe ratio of all the

analyzed samples in the same round of analysis.

Mutation nomenclature

Mutations are described at the cDNA level according to the

Human BRCA1 reference sequence: accession U14680 and

the Human BRCA2 reference sequence: accession U43746,

from GenBank sequence database (http://www.ncbi.nlm.nih.

gov/genbank/). The BRCA1 and BRCA2 numbering for the

BIC traditional mutation nomenclature are based on reference

sequences as stated above where the A of the ATG translation

initiation codon is at position 120 of BRCA1 and position 229

of BRCA2. The Human Genome Organization (HUGO) sys-

tematic nomenclature for the description of sequence variants

in DNA and protein sequences [12] follows the rule in which

the A of the ATG translation initiation codon is ?1.

Results

The BRCA1 and BRCA2 genes of 362 index cases

belonging to 326 high-risk unrelated families were scanned

for mutations. We identified a total of 14 point pathogenic

mutations (seven in BRCA1 and seven in BRCA2)

(Tables 2 and 3). Furthermore, we identified 14 variants of

unknown significance (six in BRCA1 and eight in BRCA2)

(Table 4) and 28 polymorphisms (17 in BRCA1 and 11 in

BRCA2) (Table 5). According to the type of mutation,

small deletions leading to frameshifts were more frequent

(n = 11), followed by splicing mutations (n = 1), inser-

tions (n = 1), and a missense pathogenic mutation. No

large deletions or duplications involving BRCA1/2 were

identified in a subgroup of 56 index cases negative for

BRCA1/2 point mutations.

BRCA1/2 pathogenic point mutations

Germline BRCA1/2 point mutations were found in 23

(7.1%) of the 326 Chilean families (Table 6). Despite the

low frequency of pathogenic point mutations detected in

this series, the families that had at least three BC and/or OC

cases showed the highest frequency of mutations (15.9%).

The frequency was lower for families with two BC cases

(6.6%), and two out of the nine families (22.2%) with one

BC case and one OC case were carriers of pathogenic

mutations. No BRCA1/2 pathogenic mutations were iden-

tified in the group of 57 (17.5%) early onset BC patients

(\35 years) reporting no first or second degree relatives

affected with BC or OC (Table 6). It is probable that in this

group BC is due to moderate or low penetrance genes and

not to BRCA1/2 mutations.

In the sample of 326 Chilean families, our group iden-

tified 14 point pathogenic mutations. Nine have been pre-

viously reported by our group [9], four by other groups, and

one was a new mutation not previously described. Never-

theless, it is important to emphasize that two of the previ-

ously reported mutations c.3977_3980delTGAG (BRCA1)

and c.8296delGT (BRCA2) have only two and one records

in the BIC database, respectively. The frameshift

c.3977_3980delTGAG was identified in a Chilean family

(F203), which only presented two cases of female BC

diagnosed at age 36 (index case) and at age 40 (bilateral

BC). The father of the index case was diagnosed with

prostate cancer at age 50 (Table 2). We obtained a DNA

sample only from the index case who was carrier of the

aforementioned mutation. This mutation has only two

records in the BIC database, one of them in an Asian pop-

ulation. The c.8292delGT mutation has only one record in

the BIC database. This mutation was found in family F93, a

BC/OC cancer family containing two BC cases diagnosed at

ages 26 (index case) and 32, and one OC at 60. We only

analyzed the index case and four healthy relatives (a sister, a

brother, and two cousins), and only the index case was a

carrier of the c.8296delGT mutation.

Four of the 14 distinct pathogenic mutations found by

our group were novel. To our knowledge, these have not

Breast Cancer Res Treat (2011) 126:705–716 707

123

Ta

ble

2B

RC

A1

pat

ho

gen

icp

oin

tm

uta

tio

ns

det

ecte

din

Ch

ilea

nh

igh

-ris

kfa

mil

ies

E/I

BIC

no

men

clat

ure

Sy

stem

atic

no

men

clat

ure

Eff

ect

on

amin

oac

idM

uta

tio

n

typ

e

Fam

ily

Incl

usi

on

crit

eria

Ind

exca

se

stat

us

(ag

e)

Fam

ily

his

tory

of

BC

or

OC

(ag

e)

Oth

erca

nce

rs(a

ge)

BR

CA

1

E2

c.1

87

_1

88

del

AG

ac.

68

_6

9d

elA

Gp

.E2

3fs

(Sto

p3

9)

FF

4B

BC

(38

)2

BC

(38

,6

2)

Pro

stat

e(8

2),

ute

rin

e(5

0)

E2

c.1

87

_1

88

del

AG

ac.

68

_6

9d

elA

Gp

.E2

3fs

(Sto

p3

9)

FF

46

AB

C(4

2)

3B

C(4

2,

80

,7

0)

3O

C(3

4,

41

,5

5)

Co

lon

(60

);p

ancr

eati

c(4

2,

65

);

Tes

ticu

lar

(38

);m

elan

om

a(5

4)

E5

c.3

00

T[G

ac.

18

1T[

Gp

.C6

1G

MF

13

AB

C(3

7)

4B

C(3

7,

37

,3

7,

50

)L

un

g(U

);k

idn

ey(U

)

Bo

ne

(U);

gas

tric

(35

),

pro

stat

e(U

)

E1

1c.

26

05

_2

60

6d

elT

Ta

c.2

48

6_

24

87

del

TT

p.F

82

9S

top

FF

43

BB

C(4

5)

5B

C(4

5,

49

,5

1,

51

,U

)B

il1

Ute

rin

e(U

);6

gas

tric

(U)

E1

1c.

26

05

_2

60

6d

elT

Ta

c.2

48

6_

24

87

del

TT

p.F

82

9S

top

FF

84

AB

C(4

0)

4B

C(4

0,

59

,U

,U

)2

Gas

tric

(U,

U)

E1

1c.

34

50

_3

45

3d

elC

AA

Ga

c.3

33

1_

33

34

del

CA

AG

p.Q

11

11

fs(S

top

11

15

)F

F3

6A

BC

(27

)5

BC

(27

,3

7,

37

,5

2,

79

)B

il3

ute

rin

e(U

);es

op

hag

us

(U)

E1

1c.

34

50

_3

45

3d

elC

AA

Ga

c.3

33

1_

33

34

del

CA

AG

p.Q

11

11

fs(S

top

11

15

)F

F2

53

AB

C(6

1)

(Mal

e)

5B

C(6

1,

58

,5

7,

35

,6

0)

Pro

stat

e(6

0),

pan

crea

s(6

0),

lym

ph

om

a(5

3)

E1

1c.

34

50

_3

45

3d

elC

AA

Ga

c.3

33

1_

33

34

del

CA

AG

p.Q

11

11

fs(S

top

11

15

)F

F2

98

BB

C(3

5)

2B

C(3

5,

40

)G

astr

ic(7

5),

pan

crea

s(6

0,

U)

E1

1c.

39

77

_3

98

0d

elT

GA

Gb

c.3

85

8_

38

61

del

TG

AG

p.S

12

86

fs(S

top

13

05

)F

F2

03

BB

C(3

6)

2B

C(3

6,

40

)B

il2

Gas

tric

(43

,7

1),

skin

(49

),

pro

stat

e(5

9)

E1

1c.

41

85

_4

18

8d

elC

AA

Ga

c.4

06

6_

40

69

del

CA

AG

p.Q

13

56

fs(S

top

13

64

)F

F2

1A

BC

(49

)3

BC

(45

,4

7,

49

)–

I17

IVS

17

-1G[

Aa

c.5

07

5-1

G[

Aaf

fect

edsp

lici

ng

?

r.5

19

4_

52

94

del

?

SF

65

BB

C(4

4)

4B

C(4

4,

50

,6

0,

60

)B

il3

Gas

tric

(36

,3

6,

50

);

2L

un

g(8

8,

50

);li

ver

(50

)

Co

lon

(65

);b

rain

(U)

(E/I

)E

xo

n/i

ntr

on

nu

mb

er,

?p

rob

able

effe

ct,

Ffr

ames

hif

t,M

mis

sen

se,

Ssp

lice

,B

Cb

reas

tca

nce

r,O

Co

var

ian

can

cer,

bil

bil

ater

alb

reas

tca

nce

r,U

un

kn

ow

nag

eat

dia

gn

osi

sa

Rep

ort

edin

ou

rp

rev

iou

sre

po

rt[9

]b

Als

oin

clu

ded

inB

ICas

39

75

del

AG

TG

708 Breast Cancer Res Treat (2011) 126:705–716

123

Ta

ble

3B

RC

A2

pat

ho

gen

icp

oin

tm

uta

tio

ns

det

ecte

din

Ch

ilea

nh

igh

-ris

kfa

mil

ies

E/I

BIC

no

men

clat

ure

Sy

stem

atic

no

men

clat

ure

Eff

ect

on

amin

oac

idM

uta

tio

n

typ

e

Fam

ily

Incl

usi

on

crit

eria

Ind

exca

se

stat

us

(ag

e)

Fam

ily

his

tory

of

BC

or

OC

(ag

e)

Oth

erca

nce

rs(a

ge)

BR

CA

1

E1

1c.

49

69

_4

97

0in

sTG

c.4

74

0_

47

41

insT

Gp

.S1

58

0fs

(Sto

p1

61

7)

FF

77

BB

C(3

4/4

3b

il)

2B

C(3

4/4

3b

il,

37

)E

sop

hag

us

(39

);v

esic

al(6

1)

E1

1c.

49

69

_4

97

0in

sTG

c.4

74

0_

47

41

insT

Gp

.S1

58

0fs

(Sto

p1

61

7)

FF

32

5A

BC

(34

)3

BC

(34

,4

0,

40

)P

rost

ate

(35

);3

gas

tric

(60

,6

6,

71

);3

ute

rin

e

(43

,4

5,

50

)

E1

1c.

53

74

_5

37

7d

elT

AT

Gc.

51

46

_5

14

9d

elT

AT

Gp

.Y1

71

6fs

(Sto

p1

72

3)

FF

79

AB

C(2

7)

3B

C(2

7,

27

,U

)U

teri

ne

(U)

E1

1c.

53

74

_5

37

7d

elT

AT

Gc.

51

46

_5

14

9d

elT

AT

Gp

.Y1

71

6fs

(Sto

p1

72

3)

FF

10

5A

BC

(41

)4

BC

(41

,4

3,

45

,5

7)

3P

rost

ate

(59

,U

,U

)

E1

1c.

53

74

_5

37

7d

elT

AT

Gc.

51

46

_5

14

9d

elT

AT

Gp

.Y1

71

6fs

(Sto

p1

72

3)

FF

12

7A

BC

(25

/32

bil

)3

BC

(25

/32

bil

,4

0,

50

)–

E1

1c.

53

74

_5

37

7d

elT

AT

Gc.

51

46

_5

14

9d

elT

AT

Gp

.Y1

71

6fs

(Sto

p1

72

3)

FF

28

1A

BC

(43

)4

BC

(34

,4

3,

50

,6

4)

2G

astr

ic(6

0,

80

)

E1

1c.

56

67

del

Ta

c.5

43

9d

elT

p.L

18

13

fs(S

top

18

14

)F

F3

7A

BC

(43

)3

BC

(26

,4

3,

45

)C

olo

n(U

)

E1

1c.

61

74

del

Ta

c.5

94

6d

elT

p.S

19

82

fs(S

top

20

03

)F

F4

6A

BC

(42

)3

BC

(42

,8

0,

70

)3

OC

(34

,4

1,

55

)

Co

lon

(60

);p

ancr

eati

c(4

2,

65

);

test

icu

lar

(38

);m

elan

om

a(5

4)

E1

1c.

65

03

_6

50

4d

elT

Ta

c.6

27

5_

62

76

del

TT

p.L

20

92

fs(S

top

20

98

)F

F3

9B

BC

(60

)3

BC

(60

,6

7,

70

)O

ther

can

cer

(U);

my

elo

ma

(U)

E1

1c.

65

03

_6

50

4d

elT

Ta

c.6

27

5_

62

76

del

TT

p.L

20

92

fs(S

top

20

98

)F

F3

43

CB

C(3

5)

1B

C(3

5),

1O

C(5

4)

–

E1

8c.

82

96

del

GT

c.8

06

8d

elG

Tp

.V2

69

0fs

(Sto

p2

69

1)

FF

93

CB

C(2

6)

2B

C(2

6,

32

)1

OC

(60

)U

teri

ne

(38

);lu

ng

(U)

E2

5c.

94

90

del

Gb

c.9

26

2d

elG

p.A

30

88

fs(S

top

31

03

)F

F2

11

AO

C/B

C(4

2/5

0)

1O

C/B

C(4

2/5

0)

3B

C

(38

,4

9,

67

)

Pro

stat

e(5

9),

lun

g(U

)

E/I

Ex

on

/in

tro

nn

um

ber

,F

fram

esh

ift,

BC

bre

ast

can

cer,

OC

ov

aria

nca

nce

r,b

ilb

ilat

eral

bre

ast

can

cer,

Uu

nk

no

wn

age

atd

iag

no

sis

aR

epo

rted

ino

ur

pre

vio

us

rep

ort

[9]

bM

uta

tio

ns

nei

ther

ind

exed

inB

ICn

or

inre

po

rts

by

oth

erau

tho

rs

Breast Cancer Res Treat (2011) 126:705–716 709

123

Ta

ble

4B

RC

A1

and

BR

CA

2v

aria

nts

of

un

kn

ow

nsi

gn

ifica

nce

det

ecte

din

Ch

ilea

nh

igh

-ris

kfa

mil

ies

E/I

BIC

no

men

clat

ure

Sy

stem

atic

no

men

clat

ure

Eff

ect

on

amin

oac

id

Mu

tati

on

.

typ

e(b

)

Fam

ily

Incl

usi

on

crit

eria

Ind

exca

se

stat

us

(ag

e)

Fam

ily

his

tory

of

BC

or

OC

(ag

e)

Oth

erca

nce

rs(a

ge)

BR

CA

1

E2

c.1

38

C[

Tc.

19

C[

Tp

.R7

CM

F8

6A

BC

(54

)4

BC

(54

,5

2,

55

,6

4)

Pro

stat

e(5

1)

E7

c.4

65

G[

Ca

c.3

46

G[

Cp

.E1

16

QM

F1

6C

BC

(48

)3

BC

(48

,5

3,

U)

3O

C

(70

,7

6,

U)

Pan

crea

tic

(80

);lu

ng

(66

,U

);

Lar

yn

x(7

7);

mel

ano

ma

(72

,53

);

bla

dd

er(5

0)

E1

1c.

33

99

T[A

ac.

32

80

T[A

p.Y

10

94

NM

F6

5A

BC

(44

)4

BC

(44

,5

0,

60

,6

0)

3S

tom

ach

(36

,3

6,

50

);

2L

un

g(8

8,

50

);li

ver

(50

)

Co

lon

(65

);b

rain

(U)

E1

1c.

38

67

G[

Ac.

37

47

G[

Ap

.E1

25

0K

MF

14

BU

naf

fect

ed3

BC

(30

,3

6,

47

)U

teri

ne

(U);

sto

mac

h(U

)

E1

6c.

48

61

A[

Ta

c.4

74

2A[

Tp

.E1

58

1V

MF

38

AB

C(5

2)

3B

C(5

2,

55

,6

0)

Sto

mac

h(U

);2

lun

g(U

)

E1

6c.

48

64

A[

Ca

c.4

74

5A[

Cp

.D1

58

2A

MF

38

AB

C(5

2)

3B

C(5

2,

55

,6

0)

Sto

mac

h(U

);2

lun

g(U

)

BR

CA

2

E4

c.5

68

C[

Ta

c.3

40

C[

Tp

.H1

14

YM

F1

AB

C(4

7)

4B

C(4

7,

49

,5

0,

53

)L

euk

emia

(U);

gan

gli

on

ar(U

)

E1

1c.

47

47

_4

74

9d

elA

TT

bc.

47

47

_4

74

9d

elA

TT

p.1

58

3d

elI

DF

17

9D

BC

(32

)1

BC

(32

)G

allb

lad

er(7

2),

sto

mac

h([

50

),

Leu

kem

ia([

50

),lu

ng

([5

0)

E1

1c.

50

15

A[

Ca

c.4

78

7A[

Cp

.N1

59

6S

MF

16

CB

C(4

8)

2B

C(4

8,

53

)3

OC

(70

,7

6,

?)

Lu

ng

(66

);m

elan

om

a(7

2,

53

)

E1

1c.

59

72

C[

Ta

c.5

74

4C[

Tp

.T1

91

5M

MF

40

AB

C(3

9)

4B

C(3

8,

39

,3

9,

40

)G

yn

aeco

log

ical

(U);

sto

mac

h(U

)

E1

1c.

65

18

C[

Tc.

62

90

C[

Tp

.T2

09

7M

MF

14

5E

BC

(44

,4

6)

–U

teri

ne

(50

)

E1

8c.

83

81

T[C

c.8

15

3T[

Cp

.I2

71

8T

MF

23

1B

BC

(37

)2

BC

(37

,5

0)

–

E1

8c.

83

81

T[C

c.8

15

3T[

Cp

.I2

71

8T

MF

23

9B

BC

(65

)2

BC

(65

,3

4)

Gas

tric

(65

)

E2

2c.

90

23

A[

Ca

c.8

79

5A[

Cp

.H2

93

2P

MF

10

BB

C(6

0)

3B

C(4

6,

50

,6

0)

Th

yro

id(4

3)

E/I

Ex

on

/in

tro

nn

um

ber

,M

mis

sen

se,

Dd

elet

ion

,B

Cb

reas

tca

nce

r,O

Co

var

ian

can

cer,

Uu

nk

no

wn

age

atd

iag

no

sis

aR

epo

rted

ino

ur

pre

vio

us

rep

ort

[9]

bM

uta

tio

ns

nei

ther

ind

exed

inB

ICn

or

inre

po

rts

by

oth

erau

tho

rs

710 Breast Cancer Res Treat (2011) 126:705–716

123

been reported in the BIC database or elsewhere. Three of

them were reported in our previous study and to date have

not been reported in other studies [c.2605_2606delTT

(BRCA1); c.4185_4188delCAAG (BRCA1); and c.5667delT

(BRCA2)] [9], and c.9490delG (BRCA2) is a new novel

mutation. The BRCA2 c.9490delG mutation was identified

in only one BC/OC family (F211). The family presented

three BC cases, two of them diagnosed under the age of 50,

and one OC/BC diagnosed at age 42/50. This mutation was

found in the index case (OC/BC) and in her sister affected

with BC at age 38. This mutation is located in exon 25 and

generates a stop at codon 3088, deleting 9% of the protein.

The deleted segment includes a DNA binding domain with

unique structural features for binding ssDNA and dsDNA.

Three recurrent mutations in BRCA1 (c.187_188delAG,

c.2605_2606delTT, and c.3450_3453delCAAG) and three

in BRCA2 (c.4969_4970insTG, c.5374_5377delTATG, and

c.6503_6504delTT) contributed to 63.6 and 66.7% of all

the deleterious mutations of each gene, which may reflect

the presence of region-specific founder effects. The most

frequent mutation of BRCA1 was c.3450_3453delCAAG,

found in three BRCA1 (?) families (27.3%), whereas

c.5374_5377delTATG was the most prevalent alteration in

BRCA2 (found in four families, 33.3%). Taken together,

BRCA1/2 recurrent point mutations account for 65.2% (15/

23) of the BRCA1/2 (?) families.

Variants of unknown significance

Six BRCA1 variants of the missense type were detected in

five different families (Table 4). Of these, five were

described in our previous report [9]. In BRCA2, we found

eight variants of unknown significance. Seven correspond

to missense variants, some of which are described in our

previous report [9]. In 12 of the 13 families, the variants of

unknown significance were present in the BC cases; in only

one family (F14) the variant was detected in a healthy

Table 5 BRCA1 and BRCA2 polymorphisms detected in Chilean

high-risk families

E/I (a) BIC

nomenclature

Systematic

nomenclature

Predicted

effect

BRCA1

I2 IVS2-69delTTTAa c.-62-69delTTTA Non coding

I7 IVS7?35del14a c.441?35del14 Non coding

I7 IVS7?49del15a c.441?49del15 Non coding

I7 IVS7?64delTa c.441?64delT Non coding

I8 IVS8-58delT c.548-58delT Non coding

I8 IVS8-57del7a c.442-57del7 Non coding

E11 c.2430T[Ca c.2311T[C p.L771L

E11 c.3232A[Ca c.3113A[C p.E1038G

E11 c.3667A[Ga c.3548A[G p.K1183R

I17 IVS17-53C[Ta c.5075-53C[T Non coding

I18 IVS18?66G[Aa c.5152?66G[A Non coding

I20 IVS20?60ins12 c.5277?60ins12 Non coding

I20 IVS20-57A[Ca c.5278-57A[C Non coding

I20 IVS20-56A[Ta c.5278-56A[T Non coding

I20 IVS20-46C[Ga c.5278-46C[G Non coding

I20 IVS20-45C[Aa c.5278-45C[A Non coding

I20 IVS20-27insCa c.5278-27insC Non coding

BRCA2

E2 c.203G[Aa c.-26G[A 50UTR

E10 c.1038A[Ta c.810A[T p.S270S

E11 c.2895T[Ca c.2667T[C p.N889N

E11 c.3199A[G c.2965A[G p.N991D

E11 c.3255C[Ta c.3027C[T p.F1009F

E11 c.3267A[Ga c.3039A[G p.S1013S

E11 c.3624A[Ga c.3396A[G p.K1132K

E11 c.5972T[C c.5744T[C p.M1915T

E11 c.8381C[T c.8153C[T p.I2718T

E22 c.9025A[Ca c.8797A[C p.R2933R

E22 c.9078G[Aa c.8850G[A p.K2950K

E/I Exon/Intron numbera Reported in our previous report [9]

Table 6 Frequency of families

with BRCA1 or BRCA2pathogenic point mutations

according to the inclusion

criteria

Inclusion

criteria

Tested

families

No. of families

with BRCA1 point

pathogenic mutations

No. of families with

BRCA2 point

pathogenic mutations

No. of families with

BRCA1 or BRCA2 point

pathogenic mutations

(95% CI)

A 88 6 (6.8%) 8 (9.1%) 14 (15.9%) (8.3–23.6)

B 106 5 (4.7%) 2 (1.9%) 7 (6.6%) (1.3–10.1)

C 9 0 2 (22.2%) 2 (22.2%) (0–49.4)

D 57 0 0 0 –

E 60 0 0 0 –

F 6 0 0 0 –

Total 326 11 11 23 (7.1%) (4.3–9.8)

Breast Cancer Res Treat (2011) 126:705–716 711

123

relative. In 9 of the 13 families, we obtained a DNA sample

from healthy relatives only. In family F239, the mother

with BC was a carrier of variant c.8381T[C, but her

daughter who also had BC was not a carrier. The families

who were carriers of variants of unknown significance did

not present pathogenic mutations in the BRCA1/2 genes.

The only exception was F65, which presented the c.IVS17-

1G[A mutation (BRCA1). In this family, it is likely that

the BC was a result of the pathogenic mutation c.IVS17-

1G[A. The most interesting variant is c.4747_4749del-

ATT, which produces the deletion of codon 1583, and

corresponds to a novel variant with no BIC records and not

described by other authors to date. This variant produces

the deletion of isoleucine at position 1583 of the BRCA2

protein, which was found in a BC case diagnosed at age 32

with no family history of BC or OC, and was not detected

in her healthy sister. Nevertheless, in her maternal lineage

there are relatives with gallbladder cancer, early onset

gastric cancer, leukemia, and lung cancer cases. We cannot

exclude the possibility that this mutation could be a path-

ogenic point mutation.

Discussion

In this study, we conducted a screening for point mutations

in the complete coding sequence of BRCA1 and BRCA2

genes in a group of 326 high-risk families. In addition, we

analyzed LGR in both genes in a sample of 56 high-risk BC

cases. Although there are some previous studies conducted

in Hispanic American populations such as Mexico [13],

Colombia [14], and Chile [10], this is the largest study

conducted in high-risk families in Hispanic American

population.

Evidences from different studies show that 3–50% of

familiar BC cases are accounted for by mutations in

BRCA1/2 [15]. Prevalence of BRCA1/2 mutations among

high-risk cancer patients may vary by ethnicity and study

inclusion criteria. In this study, the frequency of BRCA1/2

point mutations in the high-risk families was low (7.1%).

This percentage depends on the number of BC cancer in the

family, the presence of OC, and on the presence of male

BC. The highest frequency of BRCA1/2 mutations was

found in families (n = 88) with three or more cases of BC

or OC [15.9%, 95% CI (8.3–23.6)], and 22.2% of the

families (n = 9) with one BC and one OC were carriers of

BRCA1/2 mutations. Our results agree with those reported

by other groups in Spanish and in Hispanic American

populations. Diez et al. [16] reported 17% (95% CI

11.9–22.1) of BRCA1/2 mutation in the group of families

with three or more BC cases (n = 206). A study conducted

in Chilean population by Gallardo et al. [10] reported a

25% mutation frequency in families with three or more BC

cases [5/20 (95% CI 6.0–44.0)] [14], and in Colombian

population a 22.2% (95% CI 0–49.4) mutation frequency

was found in families with three BC cases (n = 9). In

Mexico, Ruiz-Flores et al. [13] reported that three of 17

[18% (95% CI 0–35.8)] site-specific BC families were

carriers of BRCA1/2 mutations.

No BRCA1/2 pathogenic mutations were found in the

group of early onset BC patients (\35 years), which suggests

that this group of families are likely associated with other

susceptibility genes. Previously, our group reported that in

Chilean BC cases, the RAD51-135G[C polymorphism and

the combined genotypes Thr/Met–E/G (XRCC3-T241M–

RAD51D-E233G) were associated with an increased BC risk

among women who (a) have a family history of BC, (b) are

BRCA1/2-negative, and (c) were \50 years at onset. These

findings also increased BC risk for BC cases diagnosed

before 35 years and with no family history of BC and/or OC

[17]. Also, Diez et al. [16] described low frequencies (2.6%)

of BRCA1/2 mutation for single women with BC and no

family history.

We report four novel pathogenic mutations (two in

BRCA1 and two in BRCA2). Three of them were reported

in our previous study [9], and the BRCA2 c.9490delG

mutation was described for the first time. The new muta-

tion was found in the BC/OC index case of a family that

included other three BC cases and one prostate cancer case.

The mutation was found in the index case who presented

OC at age 42 and BC at age 50 and in her sister affected

with BC at age 38. We considered c.9490delG mutation to

be a pathogenic mutation because it generates a truncated

protein at codon 3088, deleting 330 aminoacids at its C

terminus. The C-terminal aminoacids are critical because

the nuclear localization signals (NLSs) of BRCA2 reside

within the final 156 residues of BRCA2 [18]. The smallest

known cancer-associated deletion of BRCA2 is predicted to

remove 224 aminoacids (7% of the coding sequence) from

its C terminus [19]. Previous reports have indicated that all

of the known disease-linked truncation of BRCA2 is likely

to be non-functional because they do not translocate to the

nucleus [18]. Therefore, the c.9490delG is probably path-

ogenic and disease associated.

Recurrent mutations

In our first screening of BRCA1/2 mutations in a sample of

64 high-risk BC and/or OC families from Chile, we con-

clude that the BRCA gene mutation spectrum was hetero-

geneous and broad [9]. This study found three recurrent

mutations in BRCA1 (c.187_188delAG, c.2605_2606delTT,

and c.3450_3453delCAAG) and three in BRCA2 (c.4969_

4970insTG, c.5374_5377delTATG, and c.6503_6504delTT),

which contributed to 63.6 and 66.7% of all the deleterious

712 Breast Cancer Res Treat (2011) 126:705–716

123

mutations in each gene, respectively, which may reflect the

presence of region-specific founder effects.

The contemporary Chilean population stems from the

admixture of Amerindian peoples (Asians) with the Span-

ish settlers (European Caucasian) initiated in the 16th and

17th centuries. Later migrations (19th century) of Ger-

mans, Italians, Arabs, and Croatians have had only a minor

impact on the overall population (not more than 4% of the

total population) and are restricted to the specific locations

of the country where they settled [20]. The relationships

among ethnicity, Amerindian admixture, genetic markers,

and socioeconomic strata have been extensively studied in

Chile [21–23].

The most prevalent mutation in BRCA1 was c.3450_

3453delCAAG. This frameshift mutation deletes the SQ

sequences known as SQ-cluster domain (SCD) that are the

preferred sites of ATM phosphorylation. It also deletes the

entire C-terminal region that includes two regions known

as the BRCT domains. They are involved in DNA repair

pathways and bind to many proteins. The c.3450_3453

delCAAG mutation was detected in three unrelated fami-

lies. Two of these families presented five cases of BC and

the third family presented only two BC cases but with early

age at diagnosis (Table 2). According to data from BIC

database, this mutation has been identified in Norwegian,

Australian, British, Spanish, African-American, and Colombian

populations. Blesa et al. [24] detected this mutation in 2

(3.9%) out of 51 high-risk families from Eastern Spain

(Valencian Community). In Colombia, the 3450_3453del-

CAAG mutation was the most commonly observed muta-

tion in BRCA1, detected in 9.4% of the BC/OC cancer

families from this country. The Chilean and Colombian

populations have a high percentage of Hispanic admix-

tures; therefore, the presence of the c.3450_3453

delCAAG in both countries could be explained by a

founder effect of Spanish origin.

The 2605_2606delTT was reported first by our group in

the Chilean population as a novel BRCA1 mutation [9]. To

date, we have detected this BRCA1 frameshift mutation in

two Chilean families that also included cases with early age

at diagnosis (Table 2). No BIC records or other description

exist for this mutation. The affected families (F43 and F84)

with the c.2605_2606delTT mutation had Chilean ancestry

dating to many generations ago. Therefore, this mutation

could have been present in the original Amerindian popu-

lation that inhabited Chile before the colonization.

The most prevalent mutation in BRCA2 was c.5374-

5377delTATG. It was found in four families. In addition, it

was detected in other two Chilean families in a previous

report [10], for a total of six unrelated carrier families in

the Chilean population. This 4-pb deletion is also the third

most frequent BRCA2 mutation in Spain [16, 25, 26], and it

was found in 6 of 59 (10.2%) families from different

geographic areas of this country. Three of these Spaniard

families are from Castilla-Leon [27, 28]. Notably, the

Spanish settlers that arrived in Chile in the 16th century

came mainly from Central Spain, specifically from the

former kingdom of Castilla-Leon. Therefore, it is possible

that the high prevalence of c.5374-5377delTATG in Chil-

ean families may be a consequence of a founder effect of

Spanish origin. The BRCA2 c.5374_5377delTATG muta-

tion truncates the BRCA protein at codon 1732, disrupting

three out of eight BRC repeats that interact with RAD51

and the entire C-terminal region. Previous reports have

indicated that BRCA2 is associated with an older age of

diagnosis of BC [29]. On the contrary, in the Chilean

families carriers of the c.5374_5377delTATG mutation the

average age of BC onset is 42 years. Moreover, one of the

positive families presents three cases with prostate cancer

(Table 3).

The second recurrent mutation in BRCA2 is a 2-bp

insertion of TG in nucleotide 4969 in exon 11 (c.4969_

4970insTG), and it leads to a premature termination at

codon 1617. This frameshift mutation is predicted to result

in a protein truncation at codon 1617, deleting 53% of the

protein. This mutation was previously described by Gal-

lardo et al. [10] in an Italian/Chilean family. We detected

this point mutation in two unrelated families. The affected

families (F77 and F325, Table 3) had Chilean ancestry

dating from many generations ago. Both families had cases

with early age at diagnosis (B40 years), indicating a high

penetrance of this mutation. Moreover, the family F325

presents one case of prostate cancer diagnosed at age 35.

To the best of our knowledge, this mutation has not been

described in other populations.

The spectrum of recurrent mutations identified in Chil-

ean families differed completely from that of Hispanic

families of predominantly Mexican origin from Southern

California [30]. None of the six recurrent mutations iden-

tified in Hispanic families of predominantly Mexican ori-

gin in the USA were found in the Chilean families or in

Hispanic families from Colombia [14], implying that the

mutation spectra among Hispanic populations in South

America and the USA may differ.

Variants of unknown significance

In our screening of the BRCA1/2 genes, we found 14

variants of unknown significance, six in BRCA1 and eight

in BRCA2 (Table 4). In 12 of the 13 families, the variants

of unknown significance were identified exclusively in

healthy relatives; therefore, it was not possible to establish

whether they were associated with the cancers present in

the families. Only in family F239, the proband with BC

was carrier of variant c.8381T[C, but her daughter who

also had BC was not a carrier. In this family, it is likely that

Breast Cancer Res Treat (2011) 126:705–716 713

123

the variant is not the genetic cause of the BC. The most

interesting variant was c.4747_4749delATT in exon 11 of

BRCA2, which deletes isoleucine at position 1583 of the

BRCA2 protein. The BRCA2 protein directly binds to

human RAD51 through its eight BRC repeats located at the

50 region of exon 11. The number, sequence, and spacing

between these motifs are conserved during vertebrate

evolution, suggesting its functional relevance [31]. BRC3

and BRC4 (amino acids 1517–1551) repeats have the

strongest interaction with RAD51 [32]. Pellegrini et al.

[33] have solved the crystal structure of the BRC4 peptide

sequence bound to the RAD51 protein. This structure

demonstrates a series of hydrophobic and hydrophilic

interactions involving the hairpin structure of BRC4.

Contact between BRC4 and RAD51 is maintained from

Leu1521 to Glu1548 of the BRC4 sequence. The c.4747_

4749delATT mutation deletes a hydrophobic amino acid

(isoleucine) at position 1583, near to BRC4. This mutation

was found only in a BC case with no family history of BC

or OC cancer but with early age at diagnosis. Considering

that this mutation does not result in a protein truncation, it

is not possible to classify it as pathogenic. Nevertheless, we

cannot exclude the possibility that this mutation could be a

pathogenic point mutation. Functional assays are necessary

to determine how this mutation could affect critical BRC4

interaction sites.

Large genomic rearrangements

To determine the impact of BRCA1/2 LGRs in Chilean

population, 56 hereditary BC and/or OC Chilean families

negative for small mutations were screened using the

MLPA technique. This represents the first study to screen

for LGRs in BRCA1/2 in Chile and South America. No

LGRs were found in either BRCA1 or BRCA2. In different

populations, it has been reported that LGRs in BRCA1

account for 0–27% of all the disease-causing mutations,

while LGRs in BRCA2 are rare and play a minimal role in

BC/OC [34, 35]. The variation in reported percentages may

be attributable to ethnicity, inclusion criteria, or technique

used for LGRs detection. In this study, the mutation anal-

ysis for LGRs in BRCA1 and BRCA2 was performed using

MLPA, which is the most common technique for LGR

detection in the BRCA genes. The literature recommends

screening for LGRs in BRCA1 in families with multiple

cases of BC/OC and average age at diagnosis of 50 years

or less. It is also recommended to screen for LGRs in

BRCA2 in families with at least one case of male BC. In

this study, only 36 out of the 56 analyzed cases belong to

families with at least three BC/OC cases, five of which

have OC cases in their families.

With respect to ethnicity, BRCA1/2 LGRs play little or

no role in hereditary BC in Afrikaner [35], Finnish [36–

38], French-Canadian [39], and Iranian [40] populations.

The high proportion of LGRs detected in the Hispanic

population of the USA can be explained by a single

founder deletion of exons 9–12 [41]. In Spain, the fre-

quency of LGRs affecting the BRCA1/2 genes has been

estimated at around 2% in BRCA1 and 1.5% in BRCA2 in

cases previously testing negative for BRCA1/2 point

mutations [42]. In Asian populations, LGRs account for 3%

of case in Singapore [43] and 0.8% in Korea [44]. In the

Chilean group screened in this study, no LGRs were found

(0/56) in either BRCA1 or BRCA2. Is likely that such

mutations play no role in BC/OC or have a low frequency

in the actual Chilean population.

Acknowledgments The authors thank the many families who par-

ticipated in the research studies described in this article. We

acknowledge the Breast Cancer Group of CONAC: Maria Teresa

Barrios, Angelica Soto, Rossana Recabbarren, and Leticia Garcia; and

Lorena Seccia for her technical assistance. We also acknowledge the

financial support of Vicerrectoria de Investigacion y Desarrollo (VID)

Universidad de Chile (ENL 10/04) and Corporacion Nacional del

Cancer (CONAC). This study has been partially supported by a UICC

International Cancer Technology Transfer Fellowship (ICR/08/152)

and with Federal funds from the National Cancer Institute, National

Institutes of Health under Contract NO2-CO-41101, and partially

supported by a grant of the ‘‘Fondo de Investigacion Sanitaria’’ from

the Spanish Health Ministry: FIS 05/2181.

Conflict of interest The authors declare that they have no com-

peting interests.

References

1. Jemal A, Siegel R, Ward E, Hao Y, Xu J, Thun MJ (2009) Cancer

statistics, 2009. CA Cancer J Clin 59:225–249

2. Peralta O, Jorquera A, Rencoret C, Castillo CD, Sole J, Cam-

podonico Y (1995) Cancer de mama: resultados del programa de

pesquisa y tratamiento del Servicio de Salud Central. Rev Chil

Obstet Ginecol 60:417–425

3. Departamento de Estadısticas e Informacion en Salud (2009).

Mortalidad en mujeres, Chile, 2006. Ministerio de Salud de Chile.

http://deis.minsal.cl/deis/salidas06/causas06.asp?temp=TODAS_

EDADES_MUJ.htm. Accessed 14 May 2010

4. Prieto M (2006) Situacion epidemiologica del cancer de mama en

Chile 1994–2003. Rev Med Clin Condes 17:142–148

5. Easton D (2002) Familial risks of breast cancer. Breast Cancer

Res 4:179–181

6. Wooster R, Weber BL (2003) Breast and ovarian cancer. New

Engl J Med 348:2339–2347

7. Miki Y, Swensen J, Shattuck-Eidens D, Futreal PA, Harshman K,

Tavtigian S, Liu Q, Cochran C, Bennett LM, Ding W et al (1994)

A strong candidate for the breast and ovarian cancer suscepti-

bility gene BRCA1. Science 266:66–71

8. Tavtigian SV, Simard J, Rommens J, Couch F, Shattuck-Eidens

D, Neuhausen S, Merajver S, Thorlacius S, Offit K, Stoppa-

Lyonnet D et al (1996) The complete BRCA2 gene and mutations

in chromosome 13q-linked kindreds. Nat Genet 12:333–337

9. Jara L, Ampuero S, Santibanez E, Seccia L, Rodrıguez J,

Bustamante M, Martınez V, Catenaccio A, Lay-Son G, Blanco R,

Reyes J (2006) BRCA1 and BRCA2 mutations in a South

American population. Cancer Genet Cytogenet 166:36–45

714 Breast Cancer Res Treat (2011) 126:705–716

123

10. Gallardo M, Silva A, Rubio L, Alvarez C, Torrealba C, Salinas

M, Tapia T, Faundez P, Palma L, Riccio ME, Paredes H,

Rodriguez M, Cruz A, Rousseau C, King MC, Camus M, Alvarez

M, Carvallo P (2006) Incidence of BRCA1 and BRCA2 muta-

tions in 54 Chilean families with breast/ovarian cancer, genotype-

phenotype correlations. Breast Cancer Res Treat 95:81–87

11. Chomczynski P, Sacchi N (2006) The single-step method of RNA

isolation by acid guanidinium thiocyanate-phenol-chloroform

extraction: twenty-something years on. Nat Protoc 1:581–585

12. den Dunnen JT, Antonarakis SE (2000) Mutation nomenclature

extensions and suggestions to describe complex mutations: a

discussion. Hum Mutat 15:7–12

13. Ruiz-Flores P, Sinilnikova OM, Badzioch M, Calderon-Garcid-

uenas AL, Chopin S, Fabrice O, Gonzalez-Guerrero JF, Szabo C,

Lenoir G, Goldgar DE, Barrera-Saldana HA (2002) BRCA1 and

BRCA2 mutation analysis of early-onset and familial breast

cancer cases in Mexico. Hum Mutat 20:474–475

14. Torres D, Rashid MU, Gil F, Umana A, Ramelli G, Robledo JF,

Tawil M, Torregrosa L, Briceno I, Hamann U (2007) High pro-

portion of BRCA1/2 founder mutations in Hispanic breast/ovar-

ian cancer families from Colombia. Breast Cancer Res Treat

103:225–232

15. Fackenthal JD, Olopade OI (2007) Breast cancer risk associated

with BRCA1 and BRCA2 in diverse populations. Nat Rev Cancer

7:937–948

16. Diez O, Osorio A, Duran M, Martinez-Ferrandis JI, de la Hoya

M, Salazar R, Vega A, Campos B, Rodriguez-Lopez R, Velasco

E et al (2003) Analysis of BRCA1 and BRCA2 genes in Spanish

breast/ovarian cancer patients: a high proportion of mutations

unique to Spain and evidence of founder effects. Hum Mutat

22:301–312

17. Jara L, Dubois K, Gaete D, de Mayo T, Ratkevicius N, Bravo T,

Margarit S, Blanco R, Gomez F, Waugh E et al (2010) Variants in

DNA double-strand break repair genes and risk of familial breast

cancer in a South American population. Breast Cancer Res Treat

122(3):813–822. doi:10.1007/s10549-009-0709-2

18. Spain BH, Larson CJ, Shihabuddin LS, Gage FH, Verma IM

(1999) Truncated BRCA2 is cytoplasmic: implications for can-

cer-linked mutations. Proc Natl Acad Sci USA 96:13920–13925

19. Hakansson S, Johannsson O, Johansson U, Sellberg G, Loman N,

Gerdes AM, Holmberg E, Dahl N, Pandis N, Kristoffersson U,

Olsson H, Borg A (1997) Moderate frequency of BRCA1 and

BRCA2 germ-line mutations in Scandinavian familial breast

cancer. Am J Hum Genet 60:1068–1078

20. Cruz-Coke R (1976) Origen y evolucion etnica de la poblacion

chilena. Rev Med Chile 101:365–368

21. Valenzuela CY, Harb Z (1977) Socioeconomic assortative mating

in Santiago, Chile: as demonstrated using stochastic matrices of

mother–child relationships applied to ABO blood groups. Soc

Biol 24:225–233

22. Valenzuela CY, Acuna M, Harb Z (1987) Gradiente sociogene-

tico en la poblacion chilena. Rev Med Chile 115:295–299

23. Valenzuela CY (1988) On sociogenetic clines. Ethol Sociobiol

9:259–268

24. Blesa JR, Garcia JA, Ochoa E (2000) Frequency of germ-line

BRCA1 mutations among Spanish families from a Mediterranean

area. Hum Mutat 15:381–382

25. Diez O, Gutierrez-Enriquez S, Balmana J (2010) Heterogeneous

prevalence of recurrent BRCA1 and BRCA2 mutations in Spain

according to the geographical area: implications for genetic

testing. Fam Cancer 9:187–191

26. Infante M, Duran M, Esteban-Cardenosa E, Miner C, Velasco E

(2006) High proportion of novel mutations of BRCA1 and

BRCA2 in breast/ovarian cancer patients from Castilla-Leon

(central Spain). J Hum Genet 51:611–617

27. Neuhausen SL, Mazoyer S, Friedman L, Stratton M, Offit K,

Caligo A, Tomlinson G, Cannon-Albright L, Bishop T, Kelsell D

et al (1996) Haplotype and phenotype analysis of six recurrent

BRCA1 mutations in 61 families: results of an international

study. Am J Hum Genet 58:271–280

28. Tonin PN, Mes-Masson AM, Futreal PA, Morgan K, Mahon M,

Foulkes WD, Cole DE, Provencher D, Ghadirian P, Narod SA

(1998) Founder BRCA1 and BRCA2 mutations in French

Canadian breast and ovarian cancer families. Am J Hum Genet

63:1341–1351

29. Infante M, Duran M, Acedo A, Perez-Cabornero L, Sanz DJ,

Garcia-Gonzalez M, Beristain E, Esteban-Cardenosa E, de la

Hoya M, Teule A et al (2010) BRCA1 5272–1G[A and BRCA2

5374delTATG are founder mutations of high relevance for

genetic counselling in breast/ovarian cancer families of Spanish

origin. Clin Genet 77:60–69

30. Weitzel JN, Lagos V, Blazer KR, Nelson R, Ricker C, Herzog J,

McGuire C, Neuhausen S (2005) Prevalence of BRCA mutations

and founder effect in high-risk Hispanic families. Cancer Epi-

demiol Biomarkers Prev 14:1666–1671

31. Shivji MK, Venkitaraman AR (2004) DNA recombination,

chromosomal stability and carcinogenesis: insights into the role

of BRCA2. DNA Repair (Amst) 3:835–843

32. Powell SN, Willers H, Xia F (2002) BRCA2 keeps Rad51 in line.

High-fidelity homologous recombination prevents breast and

ovarian cancer? Mol Cell 10:1262–1263

33. Pellegrini L, Yu DS, Lo T, Anand S, Lee M, Blundell TL,

Venkitaraman AR (2002) Insights into DNA recombination

from the structure of a RAD51-BRCA2 complex. Nature 420:

287–293

34. Hansen TO, Jonson L, Albrechtsen A, Andersen MK, Ejlertsen B,

Nielsen FC (2009) Large BRCA1 and BRCA2 genomic rear-

rangements in Danish high risk breast-ovarian cancer families.

Breast Cancer Res Treat 115:315–323

35. Sluiter MD, van Rensburg EJ (2010) Large genomic rearrange-

ments of the BRCA1 and BRCA2 genes: review of the literature

and report of a novel BRCA1 mutation. Breast Cancer Res Treat.

doi: 10.1007/s10549-010-0817-z

36. Laurila E, Syrjakoski K, Holli K, Kallioniemi A, Karhu R (2005)

Search for large genomic alterations of the BRCA1 gene in a

Finnish population. Cancer Genet Cytogenet 163:57–61

37. Pylkas K, Erkko H, Nikkila J, Solyom S, Winqvist R (2008)

Analysis of large deletions in BRCA1, BRCA2 and PALB2 genes

in Finnish breast and ovarian cancer families. BMC Cancer 8:146

38. Lahti-Domenici J, Rapakko K, Paakkonen K, Allinen M,

Nevanlinna H, Kujala M, Huusko P, Winqvist R (2001) Exclu-

sion of large deletions and other rearrangements in BRCA1 and

BRCA2 in Finnish breast and ovarian cancer families. Cancer

Genet Cytogenet 129:120–123

39. Moisan AM, Fortin J, Dumont M, Samson C, Bessette P, Chi-

quette J, Laframboise R, Lepine J, Lesperance B, Pichette R et al

(2006) No Evidence of BRCA1/2 genomic rearrangements in

high-risk French-Canadian breast/ovarian cancer families. Genet

Test 10:104–115

40. Pietschmann A, Mehdipour P, Mehdipour P, Atri M, Hofmann

W, Hosseini-Asl SS, Scherneck S, Mundlos S, Peters H (2005)

Mutation analysis of BRCA1 and BRCA2 genes in Iranian high

risk breast cancer families. J Cancer Res Clin Oncol 131:552–558

41. Weitzel JN, Lagos VI, Herzog JS, Judkins T, Hendrickson B, Ho

JS, Ricker CN, Lowstuter KJ, Blazer KR, Tomlinson G, Scholl T

(2007) Evidence for common ancestral origin of a recurring

BRCA1 genomic rearrangement identified in high-risk Hispanic

families. Cancer Epidemiol Biomarkers Prev 16:1615–1620

42. Del Valle J, Feliubadalo L, Nadal M, Teule A, Miro R, Cuesta R,

Tornero E, Menendez M, Darder E, Brunet J, Capella G, Blanco

Breast Cancer Res Treat (2011) 126:705–716 715

123

I, Lazaro C (2009) Identification and comprehensive character-

ization of large genomic rearrangements in the BRCA1 and

BRCA2 genes. Breast Cancer Res Treat 122(3):733–743. doi:

10.1007/s10549-009-0613-9

43. Lim YK, Lau PT, Ali AB, Lee SC, Wong JE, Putti TC, Sng JH (2007)

Identification of novel BRCA large genomic rearrangements in

Singapore Asian breast and ovarian patients with cancer. Clin Genet

71:331–342

44. Seong MW, Cho S, Noh DY, Han W, Kim SW, Park CM, Park

HW, Kim SY, Kim JY, Park SS (2009) Comprehensive muta-

tional analysis of BRCA1/BRCA2 for Korean breast cancer

patients: evidence of a founder mutation. Clin Genet 76:152–160

716 Breast Cancer Res Treat (2011) 126:705–716

123