Impact of 226C>T MSH2 gene mutation on cancer phenotypesin two HNPCC-associated highly-consanguineous familiesfrom Kuwait: emphasis on premarital genetic testing

Makia J. Marafie Æ Sadiqa Al-Awadi ÆFatemah Al-Mosawi Æ Alaa Elshafey ÆWaleed Al-Ali Æ Fahd Al-Mulla

Published online: 8 August 2009

� Springer Science+Business Media B.V. 2009

Abstract Lynch syndrome or hereditary nonpolyposis

colorectal cancer (HNPCC) is one of the commonest cancer

susceptibility syndromes. It is characterized by early onset

colon cancer and a variety of extracolonic tumours. Germ-

line mutations in the DNA mismatch repair genes (MLH1,

MSH2, MSH6, PMS1, and PMS2) are responsible for this

disorder. Identifying an affected individual depends on the

tumour histopathology, family history that fulfils the

Amsterdam and/or Bethesda criteria, tumour immunohis-

tochemistry, microsatellite instability, and finally molecular

analysis of an affected member. It is a laborious, time con-

suming and expensive procedure, which needs the effort of a

multi-disciplinary team. However, once the diagnosis is

established and germline defect is identified, other high risk

pre-symptomatic carriers could be offered intensive sur-

veillance and management as a preventive measure against

cancer development. Here, we present two large highly

consanguineous HNPCC-families from Kuwait in whom a

founder MSH2 mutation was identified. The relationship

between this mutation and cancer expressivity in two large

consanguineous families harbouring other genetic defects is

discussed. Moreover, we shed light on the challenges per-

taining to diagnosis, screening, premarital counselling of

couples and prenatal diagnosis of offspring with biallelic

MSH2 gene mutation.

Keywords Biallelic mutation � Consanguinity �Founder mutation � Hereditary cancer � HNPCC �Kuwait � MSH2 gene � Premarital genetic counselling

Abbreviations

CRC Colorectal cancer

HNPCC Hereditary non-polyposis colorectal cancer

ICH Immunohistochemistry

KMGC Kuwait Medical Genetics Centre

MMR Mismatch-repair

MSI Microsatellite instability

Introduction

Hereditary nonpolyposis colorectal cancer (HNPCC)

(OMIM# 114500) is a highly penetrant autosomal domi-

nant syndrome characterized by early onset colorectal

cancer (CRC) and a variety of extracolonic malignancies

such as endometrial, hepatobiliary, ovarian, gastric, small

intestine, pancreatic, uroepithelian tract, and brain cancer.

Multiple primary tumors in the same patient have also been

frequently reported [1–3].

Many clinical criteria are being used for identifying

potential mismatch repair gene (MMR) mutation carriers;

including the Amsterdam criteria I and II, and the original

and revised Bethesda guidelines for testing of microsatel-

lite instability (MSI) in HNPCC-associated tumours [4–6].

HNPCC accounts for around 5% of all colorectal can-

cers and germ-line mutations in the DNA mismatch repair

M. J. Marafie (&)

Kuwait Medical Genetics Centre, Maternity Hospital,

P.O. Box: 5833, 13059 Safat, Kuwait

e-mail: mj_marafie@yahoo.com

S. Al-Awadi � F. Al-Mosawi � A. Elshafey

Kuwait Medical Genetics Centre, Maternity Hospital,

P.O. Box: 31121, 80901 Sulaibikhat, Kuwait

W. Al-Ali � F. Al-Mulla

Faculty of Medicine, Department of Pathology, Molecular

Pathology Unit, Kuwait University, P.O. Box: 24923, Safat,

Kuwait

123

Familial Cancer (2009) 8:289–298

DOI 10.1007/s10689-009-9275-3

genes (MMR) are responsible for this disorder [1]. Several

MMR genes (MLH1, MSH2, MSH6, PMS1, and PMS2)

have been identified. The majority (90%) of the mutations

have been described in the MLH1 and MSH2 genes, and

only 10% in MSH6. Other MMR genes are occasionally

involved [7–12]. Population based studies have agreed that

the cumulative risk for CRC development in carriers of

MLH1 and MSH2 genes is higher for males than females.

However, cancer risks varied between the different studies

[13–15]. In the Finnish population study, the cumulative

risk was 82, 60, 13 and 12% for CRC, endometrial, gastric

and ovarian cancers, respectively [14]. The cumulative

risks of CRC and extracolonic cancers in MMR mutation

carriers are important to know in these families in order to

provide accurate genetic counseling. The tumor spectrum

of Lynch syndrome will have particular diagnostic and

screening implication [16].

We offered genetic counseling to a cohort of patients

attending the familial cancer clinic at Kuwait Medical

Genetic Centre (KMGC), aiming to identify families with

hereditary cancers and to provide appropriate gene test.

Here, is the first report about a founder MSH2 mutation in

two highly consanguineous Kuwaiti families that fit the

HNPCC syndrome. Family 1 has been reported briefly

elsewhere [17]. To date, pedigree analyses for both fami-

lies revealed the presence of a total of 127 members of

consecutive generations expressing a wide spectrum of

malignancies, affecting both sexes and at different ages;

including childhood cancers in monoallelic and biallelic

carrier states. In situation like this, genetic counseling is a

life saving process, and it should include premarital and

preconceptional sessions to be provided for all at risk

members, as a preventive measure against having homo-

zygous affected children in their families.

Patients and methods

Recognizing families

Our diagnosis of hereditary cancers was through subjects

seen at the cancer genetics clinic of Kuwait Medical

Genetics Centre (KMGC), which was established in year

2000. Patients and/or relatives requested genetic counsel-

ling either by selves or were referred by oncologists,

gynaecologists, or other health professionals. Primarily

every patient was asked about the presence of other

affected family members and cancer types. Genetic coun-

sellors worked with patients and/or their key relatives in

obtaining the essential information that helped in drawing

the detailed family tree and according to a previous

agreement with probands.

Family 1

Proband 1 was a Kuwaiti female who had self approached

the clinic immediately after announcing the cancer

genetic clinic in October 2000, with an interest in genetic

counselling and predictive testing of her extended family.

Pedigree analysis revealed a large highly consanguineous

multi generational cancer family that fits Amsterdam

criteria for HNPCC (Fig. 1). So far, 79 individuals

reported to have different cancers, 10 being in young aged

individuals B20 years (Table 1). The available pathology

reports of her relatives were revised for clarification of

types and sites of malignancy. The proband had a per-

sonal history of triple primary tumours. Early in year

2000, at age 37 years, she developed infiltrating adeno-

carcinoma of the splenic flexure of the colon for which

she underwent left hemicolectomy with end to end anat-

omises, without lymph node metastasis. In the following

year, she developed transitional cell carcinoma of right

renal pelvis, for which she underwent a right nephroure-

terectomy with bladder cuff excision. No lymph node

metastasis was reported. After 3 years of our first con-

sultation she developed a small right breast mass which

proved to be of benign nature. In March 2005, she

underwent total abdominal hysterectomy with bilateral

salpingo-oopherectomy because of her endometrial well

differentiated endometroid adenocarcinoma. Her mother

had developed cyst adenocarcinoma of the ovary at age of

45 years without lymph node metastasis. However, she

died 2 years later of invasive adenocarcinoma of the

rectum. Her father developed triple primary cancers;

including colon cancer at age of 49, prostate cancer at age

62 and skin cancer at age of 77 years. One of her brothers

died at 29 years of age because of B cell non-Hodgkin’s

lymphoma, two others had colon cancer at ages of 49 and

50 years, respectively. Her niece was diagnosed with

brain stem and cerebellar glioma at age of 9 years. Three

maternal aunts and one uncle had developed colon cancer,

while 3 aunts had had endometrial cancers. The proband

had informed other family members about the genetic

defect and many individuals of different ages contacted

the cancer genetics clinic for additional information, and

requested genetic counselling and DNA testing. Some

other affected members are as seen in the pedigree

(Fig. 1).

Family 2

This highly consanguineous family was identified in 2002,

through proband 2 who had developed 2 primaries, colon

cancer and endometrial cancer at ages of 44 and 52 years,

respectively. In the same year, her 33 years sister devel-

290 M. J. Marafie et al.

123

oped colon cancer, while the sister’s daughter developed

gastric cancer at age of 7 years. Two other sisters had

developed colon cancer at ages of 35 and 38 years,

respectively, and 1 had skin cancer at her 50. Family his-

tory was consistent with Amsterdam criteria because of

presence of multigenerational colonic and extra-colonic

cancers of young ages. To date, 47 individuals were

reported to have malignancy, 11 of young ages, 1 being

brain tumours in a 20 years old male, 1 leukaemia in an

18 year old male, and 9 being childhood cancers. Proband

2 conveyed the genetic information to some of close rela-

tives in her extended family. Unaffected members were

interested in the genetic test due to the presence of the

multiple affected members especially those with childhood

malignancy (Fig. 2), and because of the concern about the

consequence of the traditionally practised cousin marriages

between individuals of the family, and between some

members of family1 and family 2.

Through extensive pedigree analysis we were able to

link these kindred to family 1 through a common male

ancestor back in the sixth generation, who had married to 2

unrelated women. Family 1 was the descendent of his son,

while family 2 was the descendant of his daughter by the

second wife.

Table 1 Tumour site and average age at onset for 127 affected

individuals in family 1 and 2

Tumour site Family 1 Family 2 Total

Average

age

No. of

tumours

Average

age

No. of

tumours

Colon 45 53 43.2 16 69

Endometrium 47.4 12 41 3 15

Stomach 20 1 13.5 2 3

Brain 24.8 5 30.3 4 9

Breast 46 2 42 6 8

Ovary 37.5 2 0 0 2

NHL 36.75 4 26.5 6 10

Leukaemia 19 3 14.6 5 8

Kidney 46.7 3 0 0 3

Prostate 62 3 0 0 3

Larynx 0 0 36 2 2

Pharynx 0 0 39 1 1

Maxilla 0 0 31 2 2

Skin 73 2 52.5 2 4

Total tumours

all sites

90 48 139

Total number of

patients

79 47 127

Total number of tumours is 139, found in 127 affected members of

both families. Nine individuals developed more than 1 primary

tumour, being eight in family1 and one in family2

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Impact of 226C[T MSH2 gene mutation 291

123

Sample collection

Immunohistochemistry for MMR protein

About 3–4 lm thick paraffin embedded tumour-sections

were cut and mounted on to glass slides. After dewaxing and

rehydration of sections, antigenic site retrieval was accom-

plished by microwaving each slide for 20 min in 0.01 M

citric acid buffer (pH 6.0). Endogenous peroxidase activity

was blocked by incubation with 2% hydrogen peroxide for

15 min. Sections were subsequently incubated with either

monoclonal anti-MSH2 clone.FE11 or anti-MLH1 clo-

ne.ZM001 antibodies (Zymed, San Francisco, California,

USA) or MSH6 clone GTBP or PMS2 clone.A16-4 (BD

PharMingen) overnight at 40�C. Biotinylated secondary

antibody was added to the sections and incubated for 30 min

at room temperature. Antibody binding was detected using

the Elite Vectastain ABC kit (Vector Laboratories Ltd,

Peterborough, UK), which is based on the biotin-avidin

system, using the manufacturer’s protocol. The reaction was

visualized using DAB (Vector Laboratories Ltd). Sections

were then dehydrated and mounted. Normal colorectal tissue

adjacent to the carcinoma was used as the positive control.

Loss of expression was recorded when nuclear staining was

observed in normal tissue but not in adjacent malignant cells.

DNA extraction and sequencing

Initially blood sample was collected from 3 selective in

consenting affected-members in each family. Having

established the lack of MSH2 protein expression in the

tumour of the proband, mutation analysis was performed

on genomic DNA isolated from peripheral blood lympho-

cytes by using DNA extraction kit from blood (Qiagen Inc,

Valencia, Calif). Polymerase chain reaction (PCR) ampli-

fication was performed on genomic DNA for all 16 exons

of MSH2 and entailed a preincubation of 95�C for 10 min

followed by 30 cycles of denaturation at 95�C for 30 s,

annealing at 53�C for 45 s, and extension at 72�C for 45 s.

The PCR products then were purified using QIAquick PCR

Purification kit (Quiagen, Chatsworth, CA, USA) and then

verified in 1.5% agarose gel electrophoresis. All gene

segments were sequenced in both forward and reverse

directions using an ABI 3130 automated DNA sequencer

(Applied Biosystems, Foster City, Calif) and the Big Dye

terminator cycle sequencing Ready Reaction-Kit (PE

Applied Biosystems, Weiterstadt, Germany) using the

manufacturer instructions.

All adults and relatives of children were counselled and

signed informed consent forms before the tests were

performed.

Result

Immunohistochemistry and mutation analysis

Immunohistochemistry for mismatch repair proteins,

namely MLH1, MSH2, MSH6 and PMS2 was performed

Fig. 2 Pedigree of family 2 showing part of the extended family.

Black symbols affected; open symbols normal; diagonal barsdeceased; double bars consanguinity. Proband 2 is indicated by an

arrow

292 M. J. Marafie et al.

123

on the affected proband. Figure 3 shows lack of MSH2

nuclear expression in colorectal cancer tissues. Accord-

ingly, this result targeted us to sequence all 16 exons of the

MSH2 gene. Figure 4 shows the exon2 226 C[T mutation

identified in both families. This mutation results in termi-

nation at codon 76 (Q76X).

Tumour type

To date, we have collected information from 127 affected

individuals, being 79 in family 1 and 47 in family 2

(Table 1). Malignancy varied by gender and age, extended

pedigree analyses and pathology reports of some individ-

uals, revealed a total of 139 different cancers segregating

through multiple generations and different family tree

branches (Figs. 1, 2). There were 90 different cancers in

family 1 and 49 in family 2. In family 1; 8 members have

developed more than one primary tumour, while in family

2 only proband 2 had had double primaries (Table 2, 3).

However, in both families we were unable to clarify pre-

cisely some of the gastrointestinal tumour sites, which said

to be CRC, in the deceased 5th and 6th generational

members. Several other members of both families expres-

sed few colonic polyps.

Gene mutation

Sequence analysis of the aberrant DNA band identified a C

to T base substitution at nucleotide 226 in codon 76 of

MSH2 gene, converting the glutamine amino acid (CAG)

to a TAG stop signal (Q76X). This nonsense mutation is

novel and predicted to cause premature truncation of the

protein product.

Fig. 3 Immunohistochemical

staining for MSH2 protein

shows loss of nuclear expression

in the colonic adenocarcinoma

(a) and retained expression in

normal mucosa (b) (409

Magnification)

Fig. 4 a Reverse sequence trace of MSH2 exon 2 showing 226C[T heterozygous mutation (Arrow) in proband. b Normal control MSH2 exon 2

sequence

Impact of 226C[T MSH2 gene mutation 293

123

All together, we have analysed the genomic DNA of 121

living members; 35 mutation carriers were indentified, 17

were affected; being 10 in family 1 and 7 in Family 2. At

the time of testing, 18 were presymptomatic being 12 in

family 1 and 6 in family 2.

Family 1

We have observed that CRC was the most common pre-

senting type; 53/90 tumours, (58.9%) of all types (Table 1).

Mutation was proved in six living affected members.

Among women in family 1, endometrial cancer was the

second common manifestation, reported 12 times (13.3%),

2 of the living were carriers. Ovarian cancer was reported

in two women, one of whom was 30 years old, just mar-

ried, and proved to be a mutation carrier. In general, of the

ten carriers with malignancy, two individuals developed

three different types of primary tumours (Table 2).

The proband’s niece whom was diagnosed with brain

glioma at age of 9 years tested negative for the mutation,

though she was heterozygote for IVS1.5 in the Beta-globin

gene. She developed a benign breast mass at age of

16 years. Her mother was a presymptomatic carrier. She

was put under coordinated intensive surveillance protocol,

where 3 years later, at 47 years of age, developed endo-

metrial polyp with squamous metaplasia, which was fol-

lowed by prophylactic total hysterectomy and bilateral

salpingo-oophorectomy. Additionally, her 9 years old son

was investigated for gastric erosions, however, proved to

be of a benign nature. A second cousin male relative, son of

a female with colon cancer, found not carrying the MSH2

gene mutation; though had developed hamartomatous

polyposis at age of 55 years. Also, a first cousin female

who developed few oesophageal polyps was negative for

the mutation. So far, both individuals are under effective

preventive measures. Mutation was not found in 2 second

cousins; a male and a female relatives who had their breast

cancers at age 45 and 48, respectively.

Family 2

In family 2; colon cancer was the mostly manifested

malignancy in both sexes; 16/48 (33.3%). Endometrial

cancer was detected in three women, breast cancer in four

women, while brain and haematological cancers were found

in seven young members under the age of 20 years

(Table 2). The granddaughter of proband 2, a seven years

old girl who had developed gastric cancer found to be a

mutation carrier, while her mutation carrier mother devel-

oped colon cancer at age of 33 years. Moreover, the three

young grand children of proband 2, with T-cell non-Hodg-

kin lymphoma were found to be homozygotes for the

mutation [18]. A male grandchild of proband 2, carrier for

the mutation, had brain cancer at age of 17 years and died

1 year later. An unmarried mentally retarded daughter of

proband 2 had colonic polyps and developed breast cancer

recently at age 44 of years; though her carrier status is

unknown yet. Additionally, a female second cousin relative

of proband 2 developed breast cancer at age of 38 years,

while her sister and her mother had their breast cancers at 40

and 48 years, respectively. Mutation in MSH2 gene was

excluded in her. Moreover, she has been included in BRCA1

gene screening group where 50% of the gene was tested so

far, but no mutation was identified. Furthermore, breast

cancer reported to be segregated in other parts of this family,

which are not shown in the pedigree (Fig. 2). Additionally,

mutation was excluded in 2 members, a sister of proband 2

with skin cancer at age of 50 and a second cousin male, who

developed pharyngeal cancer at age of 39 years.

Table 3 Tumour site and age at onset for six individuals in both

families reported with double primary tumours

Patients no. Tumour site

1st 2nd

Family 1

Patient 1 Caecum Rectum

Age 32 39

Patient 2 Caecum Rectum

Age 45 52

Patient 3 Colon Endometrium

Age 49 56

Patient 4 Colon Endometrium

Age 40 50

Patient 5 Colon Ovary

Age 54 45

Family 2

Patient 6 Colon Endometrium

Age 44 52

Patient 6 is proband 2

Table 2 Tumour site and age at onset for 3 individuals with triple

primary tumours in Family 1

Patients no. Carrier status Site of primary tumour

1st 2nd 3rd

Patient 1 Yes Colon Kidney Endometrium

Age 37 38 41

Patient 2 Yes Colon Prostate Skin

Age 49 62 77

Patients 3 Not done Kidney Prostate Skin

Age 55 66 72

Patient 1 is proband 1, patient 2 is her father, patient 3 is his second

cousin. Patients 2 and 3 had basal cell carcinoma of the skin

294 M. J. Marafie et al.

123

Premarital testing

With the high demand for first or double cousin mar-

riages, the presence of inter and intra-familial arranged

marriages between both families, and due to the existence

of Alfa/Beta-thalassemia, sickle cell and G6PD diseases

segregating in some parts of the two families, more effort

was put on premarital diagnosis of high risk couples.

Premarital testing of 11 first cousin couples; the offspring

of mutation-carriers, was effective, 19 out of 22 partners

proved to be negative for the MSH2 mutation. While for

3 couples, only one partner was an MSH2 mutation car-

rier. Moreover, in 1 of the 11 tested couples; both part-

ners were carriers for Beta-thalassemia trait, hence

another unaffected first cousin female partner was chosen

by a mutual agreement. In one couple set; the female had

Alfa-thalassemia trait, the male had G6PD disease. In

another couple set; one partner had G6PD disease and

sickle cell trait. Moreover, one female partner with beta-

thalassemia trait was found to be double heterozygote; for

IVS1.5 in the Beta-globin gene, which was inherited from

her father, and for MSH2 mutation passed from her

mother (proband1), yet her partner was normal. In one

set; the female had history of brain tumour, negative for

MSH2, but carrier of IVS1.5 in the Beta globin gene,

while the partner was normal.

Discussion

We report two highly consanguineous Kuwaiti families

fulfilling the Amsterdam criteria for HNPCC syndrome,

with respect to multi-generational cancer affected members

and early age of onset (Figs. 1, 2). A novel germline MSH2

gene mutation was harboured by 35 individuals, of whom

17 had developed a variety of malignancies, while 18 were

presymptomatics. Carriers of an MMR-gene defect have

the highest risk of developing CRC and endometrial can-

cer. The individual risk varied widely within and between

the previously reported HNPCC families [14]. In our

families, CRC constitutes the majority of diagnosed can-

cers in both sexes (Table 1). Moreover, extracolonic

tumours were variably presented in different age groups

and genders. Extracolonic tumours, except for endometrial

cancer, have been reported to be more frequent in MSH2

than MLH1 mutations [19]. We observed interfamilial

variability in the phenotypic expression of this mutation

between carriers in the two families. In family 1; endo-

metrial cancer was the second most common malignancy

expressed in carrier/obligate carrier-females. Transitional

cell carcinoma, an HNPCC related tumour of the urinary

tract was also seen in three members of both sexes in

family 1 but not 2. Only three endometrial cancers were

present in family 2. This phenotypic difference could be

attributed perhaps to effect of other modifying genes or

environmental factors not shared between both families.

Perhaps one of the most intriguing finding of this study

was the appearance of multiple synchronous or metachro-

nous cancers in individuals carrying the MSH2 Q76X

mutation in both families, albeit more frequent in Family 1.

Although it is well known that HNPCC patients are prone

to develop multiple cancers, the extent of this involvement

especially pertaining to the Q76X mutation has not been

fully appreciated before. Therefore, studies involving such

large and highly consanguineous families could shed more

light on the influence of a specific mutation on cancer

phenotypes.

Childhood malignancy was frequently seen in the

youngest generation of both families; including Leukae-

mia, lymphoma, gastro-oesophageal and brain cancers. In

family 2, three sibs with T-cell non-Hodgkin lymphoma

(NHL) carried a homozygote germline mutation in MSH2

gene. Several publications indicated that biallelic muta-

tions in the MMR genes are associated with a more severe

phenotype, including childhood malignancies like Wilms

tumour, Leukaemia, lymphoma, gastrointestinal and brain

cancer. These phenotypes were frequently associated with

areas of skin hypo-pigmentation or multiple cafe-au-lait

spots similar to the signs of neurofibromatosis type I (NF1)

[18, 20–24]. This emphasizes the importance of investi-

gating their family history for HNPCC related cancers.

The 9 years old girl of family 1 with brain glioma

proved to be negative for this mutation. Mutation in

another gene is not excluded, especially when she devel-

oped a benign breast mass at age of 16 years. Some other

young onset patients of family 2, found to carry single copy

of the defective MSH2 allele, also they did not carry the

skin manifestations found in the biallelic young patients.

This is probably explained by the effect of modifier factors,

mutation in other part of the MSH2 gene that cannot be

identified by the current techniques, or sharing other

homozygous defective alleles/gene(s) by descent. Com-

pound heterozygosity for two MSH6 mutations in a patient

with early onset of HNPCC-associated malignancy has

been reported previously [25].

Moreover, we have observed an earlier age at onset in

the most recent generations of both families. In family 1;

age at onset was 30 years or younger for 17/79 (21.5%)

affected members, 8 out of 17 (47%) were 20 years old or

younger (Table 1). Three out of the 8 were alive and tested

positive for the mutation. The youngest person was 9 years

old girl with brain tumour, however, she proved not to be a

carrier. While in family 2; age at onset was 30 years or

younger for 15/48 (31.3%) affected members, 12 out of 15

(80%) were 20 years old or younger. However, the youn-

gest age at onset was just about 1 year; a girl with NHL.

Impact of 226C[T MSH2 gene mutation 295

123

Four of the 12 were living and showed to be carries for the

mutation, 3 of whom were homozygotes with presymp-

tomatic carrier parents. The one who was heterozygote,

developed gastric cancer at age of 7 years, her mother

developed colon cancer at age of 33 years, while the

maternal grandmother had had her colon cancer at age of

45 years. The youngest age for ovarian cancer was

30 years, while for endometrial cancer was 40 in family 1.

Genetic anticipation was postulated recently by the

Danish group study as an explanation for younger age at

onset in HNPCC-families, and possibly influenced by

expansion of some repeat sequences other than the known

trineocleotide repeats, which are responsible for many

neurological and psychiatric disorders [26]. However, this

hypothesis has not been accepted by some other authors

[27]. Further studies are needed to explore the biological

bases of genetic anticipation in HNPCC-families with

defective MMR genes. In our younger patients, it is pos-

sible that other unidentified genetic/epigenetic or modify-

ing factors are implicated. The clinical implication for over

generational decreasing of age at onset creates an extra

dilemma for management of these families, not only for the

type of malignancy to monitor, as colonic or extracolonic,

but also for what age to start at. In our families the

youngest age for colon cancer was 18 years (family 1) and

for gastric cancer was 7 years (family 2). Which guidelines

should we follow for initiating colonoscopy or gastroen-

doscopy in order to identify a premalignant abnormality?

Some extracolonic tumours have no recommendation for

surveillance of HNPCC-families [16, 28]. This dilemma

will remain unresolved in such families, until other

implicated genetic factors or associated rare variants are

clearly uncovered. Consequently, special therapeutic and

prevention measures need to be implemented. Knowing the

causative mutation in these families helped in identification

of the presymptomatic high risk members, hence selecting

them for highly targeted surveillance programs, for pre-

vention and early detection of HNPCC-associated cancers,

in an attempt to decrease cancer mortality and morbidity in

both families.

First, second and double first cousin marriages are

practised frequently in Middle Eastern families [29–32],

which require providing premarital genetic counselling to

couples from the families with recognized inherited dis-

eases. Moreover, in some consanguineous families, more

than one genetic disorder of differing inheritance is occa-

sionally seen in families attending our genetic clinics;

including hereditary cancers. Cancer prevalence was

reported to be higher in adults of the consanguineous

families from Qatar [31]. This complicates the decision if

the gene defect is not yet identified, or if no targeted lab-

oratory test is currently available. At the start the MSH2

genes mutation formed a dilemma for genetic counselling

of the two consanguineous HNPCC families, where other

diseases as mental retardation and haemoglobinopathies

were additionally segregated. However, counselling proved

to be effective in both families. We found great response

from all members whom were contacted by proband 1.

Over 8 years, many members approached the KMGC

seeking counselling and predictive testing, and the number

is continuously rising. We arranged for molecular screen-

ing of other requesting at-risk distant relatives, for referrals

to the appropriate specialists for consultation, and for

effective disease prevention, which includes frequent col-

onoscopies and pelvic ultrasound, as well as prophylactic

colectomy and/or hysterectomy and early breast cancer

screening. Moreover, KMGC arranged an education and

training program for family practitioners in an attempt to

increase awareness of the consequence of consanguineous

mating in families with hereditary cancers.

So far, this founder MSH2 gene mutation was absent in

four other Kuwaiti HNPCC-families, although the ances-

tors for two of them were traced back to east province of

Kingdom of Saudi Arabia, similarly to Family 1 and family

2, but with no genealogical connection with any of them.

This indicates that other unidentified mutations in the same

gene or another MMR gene(s) are involved. Hence it is not

the only founder mutation in our population. These families

are still under investigation.

Conclusion

In Kuwait consanguinity rate is high (54.3%), compared to

Western countries with a large family size, high inbreeding

coefficients within Kuwaiti native population as well as the

residing Arab community, and frequently practised double

cousin marriages [29, 30]. This necessitates recognizing

high risk hereditary cancer families. Identification of

genetic cancer is essential so that cancer surveillance can

be implemented or prophylactic surgery carried out in the

at-risk members. Recognition of high risk families to

increase their awareness is a task that needs a multi dis-

ciplinary medical team working with clinical geneticists.

This can be achieved by increasing the genetic awareness

of all medical specialities, including primary care provid-

ers, family practitioners and the oncologists involved in the

diagnosis and treatment of cancer, by arranging education

and awareness programs. Hence a family specific pre-

ventive program and management strategy is required to be

implemented including genetic counselling and testing.

Also, keeping in mind that termination of pregnancy is

prohibited on religious bases in the Muslim world. There-

fore, in such genetically predisposed families, preimplan-

tation genetic diagnosis should be offered as the best option

for proactive management for mutation carrier couples who

296 M. J. Marafie et al.

123

have been already married, and with high risk of producing

homozygous offspring. Early marriage and pregnancy is

also to be encouraged in particular for female carriers,

because of the high risk for development of HNPCC-

related ovarian cancer at a young age, which might require

prophylactic oopherectomy and hysterectomy. Also,

molecular screening should be offered as part of the pre-

marital routine investigations for members of such high

risk cancer families who proved to harbour identifiable

germline mutations in one of the responsible genes.

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