Spectrum of genes for inherited hearing loss in the Israeli Jewish population, including the novel human deafness gene ATOH1.

Mutations in more than 150 genes are responsible for inherited hearing loss, with thousands of different, severe causal alleles that vary among populations. The Israeli Jewish population includes communities of diverse geographic origins, revealing a wide range of deafness-associated variants and enabling clinical characterization of the associated phenotypes. Our goal was to identify the genetic causes of inherited hearing loss in this population, and to determine relationships among genotype, phenotype, and ethnicity. Genomic DNA samples from informative relatives of 88 multiplex families, all of self-identified Jewish ancestry, with either non-syndromic or syndromic hearing loss, were sequenced for known and candidate deafness genes using the HEar-Seq gene panel. The genetic causes of hearing loss were identified for 60% of the families. One gene was encountered for the first time in human hearing loss: ATOH1 (Atonal), a basic helix-loop-helix transcription factor responsible for autosomal dominant progressive hearing loss in a five-generation family. Our results show that genomic sequencing with a gene panel dedicated to hearing loss is effective for genetic diagnoses in a diverse population. Comprehensive sequencing enables well-informed genetic counseling and clinical management by medical geneticists, otolaryngologists, audiologists, and speech therapists and can be integrated into newborn screening for deafness.

Genotype-phenotype correlation in the presentation of retinoblastoma among 149 patients.

In this work, we describe the association between a germline RB1 mutation and disease presentation characteristics of retinoblastoma. The study evaluates a retrospective cohort of 164 of the 295 patients with retinoblastoma who were treated at a single center between 1988 and 2013 and who were referred for genetic evaluation. Peripheral blood was evaluated for RB1 mutations via Multiplex Ligation-dependent Probe Amplification (MLPA), sequencing, and detection of recurrent CpG transition mutations. Patients with an RB1 mutation were compared to patients without a mutation, regarding epidemiological factors and clinical presentation. Genetic analysis was completed for 149 patients. An RB1 mutation was identified in 76 children (51.0%) including 90.0% of the bilateral patients, and 19.8% of the unilateral unifocal patients (24.7% if we include the unilateral multifocal cases). The most common mutations were a stop codon (38.2%), a splicing error (19.7%) and a large deletion (15.8%). The mutation type correlated only with sex (Likelihood ratio, p = 0.0240) and with macular involvement (Likelihood ratio, p = 0.0591 and Fisher's exact one tail test p = 0.0459 for more macular involvement if there are germline mutations). It did not correlate with laterality, with the reason for referral, or with diagnosis age. However, identification of a mutation was more common in babies diagnosed under one year of age (Likelihood ratio, p < 0.0001). In conclusion, we were surprised that our genetic tests have also found mutations in 24.7% of patients with unilateral retinoblastoma in addition to most of the bilateral children. These unilateral patients with a germline mutation have an increased risk for other cancers throughout their lives, and their first-degree relatives have an increased risk for retinoblastoma. Therefore, genetic testing for RB1 mutation should be offered to all patients, including the unilateral cases.

Patients' Attitudes Towards Disclosure of Genetic Test Results to Family Members: The Impact of Patients' Sociodemographic Background and Counseling Experience.

Many factors predict the intention to disclose genetic information to relatives. The article examines the impact of patients' socio-demographic factors on their intention to disclose genetic testing results to their relatives. Data were collected in eight genetic clinics in Israel. Patients were requested to fill in a questionnaire after counseling. A convenience sample of 564 participants who visited these clinics was collected for a response rate of 85 %. Of them, 282 participants came for susceptibility testing for hereditary cancers (cancer group), and 282 for genetic screening tests (prenatal group). In the cancer group, being secular and having more years of education correlated positively with the intention to disclose test results to relatives. In the prenatal group, being married and female correlated positively with the intention to disclose. In the cancer group, being religious and with less years of education correlated positively with the view that the clinician should deliver the results to the family. In the prenatal group, being male and unmarried correlated positively with this belief. In both groups, being of young age correlated with the perception that genetic information is private. Varied sociodemographic factors affect the intention to inform family members. Thus, knowing the social background of patients will shed light on people's attitudes to genetic information and will help clinicians provide effective counseling in discussions with patients about the implications of test results for relatives.

Genetic predisposition to radiation induced sarcoma: possible role for BRCA and p53 mutations.

The estimated incidence of radiation-associated sarcoma (RAS) is 0.03-0.2 % in 5 years post treatment. Most cancer predisposing genes are involved in DNA repair; therefore, elevated RAS risk in these patients is plausible. Cases of angiosarcoma post breast cancer treatment were reported in BRCA1 and BRCA2 carriers. We report the genetic evaluation of seven cases with suspected RAS from patients counseled in our cancer-genetic clinic. Of 2,885 breast cancer patient, 470 were BRCA1 or two mutation carriers and three were p53 mutation carriers. Of them seven developed sarcoma in the field of irradiation; five in the chest wall and two in other sites. Genetic evaluation revealed BRCA1 mutation in two, BRCA2 mutation in additional patient and a carrier of p53 mutation. The estimation of risk for RAS in patients with genetic predisposition is limited due to the rarity of this event, and the bias in referral to the clinic toward younger age. With these limitations the rate of RAS is 0.43 % (2/470, 95 % CI -0.17 to 1.02, SE = 0.3) in this group in a median follow-up of 8.2 years (range 1 month to 51 years). If we assume irradiation for the breast in 80 % of the patients than rate of RAS in group is proximately 0.53 % (2/376, 95 % CI -0.21 to 1.26, SE = 0.37). A BRCA1 carrier which had sarcoma after irradiation to head and neck carcinoma was not included in these analyses. In conclusion, we found a high frequency of BRCA1/2 mutation among our patients diagnosed with RAS. However, we estimated approximately twofold increase in the risk of RAS in BRCA1/2 carriers which was not significant compared to reports in general population. Therefore, RAS is a rare event in BRCA carriers as in the general population, and should not be considered in the decision regarding irradiation treatment in this population.

Genetic counseling services and training of genetic counselors in Israel: an overview.

Genetic counseling services have existed in Israel since 1964 and are available in almost all the major hospitals. Given the socialized healthcare system and small country size, genetic services are generally accessible and often free. The existence of founder mutations in various communities in Israel makes genetic testing easier to perform. Yet, the ethnic, cultural and religious diversity of the population has major implications on the design of the screening programs and the use of genetic services. The Israeli Association of Genetic Counselors (IAGC) was established in 2008 and had existed informally since 1989. There are two Master level genetic counseling training programs (6 students/class, 2 year program): Hebrew University-Hadassah Medical School (established in 1997) and the Technion (established in 2009). Genetic counselors' clinical training is largely observational and 2 years of supervised counseling sessions post degree are required for board exam eligibility. Genetic counselors are licensed and lead counseling sessions individually, but currently must work under medical geneticist supervision. This is the first article to summarize the history and training of Master level genetic counselors in Israel. Genetic services, coverage and regulations are also described.

Incorporating information regarding preimplantation genetic diagnosis into discussions concerning testing and risk management for BRCA1/2 mutations: a qualitative study of patient preferences.

BACKGROUND: Studies have shown that BRCA1/2 mutation carriers are interested in learning about reproductive options such as preimplantation genetic diagnosis (PGD) to prevent passing their risk onto their children. However, attitudes vary widely, and the procedure raises complex ethical and psychosocial issues. This complexity, plus the highly technical nature of PGD, makes it difficult to integrate PGD information into genetic counseling sessions that already cover probabilistic, emotionally charged risk information. METHODS: A total of 33 carriers of the BRCA1/2 mutation who were of reproductive age and had previously undergone genetic counseling viewed a tutorial regarding PGD and were interviewed concerning their attitudes toward PGD and preferences about how to include PGD information in genetic counseling. RESULTS: The majority of participants preferred to be briefly informed of the availability of PGD information, and to receive written materials regarding PGD, but with the option of deferring detailed discussion if they already believed themselves to be overloaded or perceived that PGD was not immediately relevant to their risk management and/or childbearing plans. For some individuals, the stress of testing temporarily interfered with information processing, producing states of cognitive avoidance ("in a fog," or "tuning out"). Some preferred to discuss PGD with a physician with whom they had an ongoing relationship (eg, obstetrician/gynecologist, primary care provider, or oncologist). CONCLUSIONS: Providers offering cancer genetic testing may consider indicating the availability of PGD information to their patients, while attending to the patients' level of interest and ability to absorb information. Research is needed to link patient responses to information overload with psychosocial outcomes (eg, distress, and quality of decision-making). Continuing medical education is needed to support providers in facilitating informed decisions regarding PGD.

Genome-wide SNP genotyping identifies the Stereocilin (STRC) gene as a major contributor to pediatric bilateral sensorineural hearing impairment.

Hearing loss is the most prevalent sensory perception deficit in humans, affecting 1/500 newborns, can be syndromic or nonsyndromic and is genetically heterogeneous. Nearly 80% of inherited nonsyndromic bilateral sensorineural hearing loss (NBSNHI) is autosomal recessive. Although many causal genes have been identified, most are minor contributors, except for GJB2, which accounts for nearly 50% of all recessive cases of severe to profound congenital NBSNHI in some populations. More than 60% of children with a NBSNHI do not have an identifiable genetic cause. To identify genetic contributors, we genotyped 659 GJB2 mutation negative pediatric probands with NBSNHI and assayed for copy number variants (CNVs). After identifying 8 mild-moderate NBSNHI probands with a Chr15q15.3 deletion encompassing the Stereocilin (STRC) gene amongst this cohort, sequencing of STRC was undertaken in these probands as well as 50 probands and 14 siblings with mild-moderate NBSNHI and 40 probands with moderately severe-profound NBSNHI who were GJB2 mutation negative. The existence of a STRC pseudogene that is 99.6% homologous to the STRC coding region has made the sequencing interpretation complicated. We identified 7/50 probands in the mild-moderate cohort to have biallelic alterations in STRC, not including the 8 previously identified deletions. We also identified 2/40 probands to have biallelic alterations in the moderately severe-profound NBSNHI cohort, notably no large deletions in combination with another variant were found in this cohort. The data suggest that STRC may be a common contributor to NBSNHI among GJB2 mutation negative probands, especially in those with mild to moderate hearing impairment.

Clinical and genetic heterogeneity of congenital adrenal hypoplasia due to NR0B1 gene mutations.

INTRODUCTION: X-linked adrenal hypoplasia congenita (AHC) is a rare disorder caused by mutations or complete deletion of the NR0B1 gene that encodes the DAX-1 protein, an orphan member of the nuclear receptor superfamily. AHC is characterized by adrenal insufficiency in infancy and early childhood. Later, hypogonadotropic hypogonadism (HH) manifests as pubertal failure. PATIENTS AND METHODS: We evaluated the clinical, endocrine and molecular characteristics of 12 AHC patients from 5 families diagnosed between 1984 and 2007 in Israel. RESULTS: Most of the boys (10/12) presented with signs of adrenal insufficiency such as salt wasting and failure to thrive during the neonatal period. Aldosterone deficiency usually preceded cortisol deficiency requiring early mineralocorticoid therapy. Serum cortisol levels in the first weeks of life varied from very low to high levels (<2.76 to >1776 nmol/l). Five boys showed signs of precocious sexual development during infancy and childhood, including enlargement of the penis and testes. In four patients the initial diagnoses were erroneous. Molecular analysis of the NR0B1 gene identified point mutations in six patients including a novel splice site mutation in one patient and his family (IVS1-1G-->C). Contiguous gene deletion was found in six patients from two families who manifested impaired mental development. CONCLUSIONS: In X-linked AHC caused by different molecular defects in NR0B1 gene, the clinical spectrum of the disease is quite variable and precocious sexual development is a prominent feature. Genetic testing is indicated in boys presenting with salt-wasting with or without cortisol deficiency if congenital adrenal hyperplasia has been ruled out.

Mutation spectrum in HNPCC in the Israeli population.

Hereditary non-polyposis colon cancer is caused by mutations in DNA mismatch repair genes. The mutation spectrum in the Israeli population is poorly documented except for the c.1906G>C Ashkenazi founder mutation in the hMSH2 gene. To report our experience in HNPCC screening, the mutations detected and the clinical features among a cohort of Israeli patients. Diagnostic work-up was done in a multi-step process guided by clinical and ethnic information. Tumors of suspected patients were tested for microsatellite instability and immunohistochemistry. Based on tumor analyses, we proceeded to mutation screening by DHPLC followed by sequence analysis and multiplex ligase dependent probe amplification. Ashkenazi Jews were first tested for the c.1906G>C founder mutation. Of the 240 families, 24, including Arabs and Jews from different ethnic origins, were tested positive. All tumors that lost expression of mismatch repair proteins also showed microsatellite instability. There was evidence for involvement of hMSH2 (15) hMLH1 (6) and hMSH6 (3) genes. Mutations were identified in 17/24 (71%) patients: 6 Ashkenazi families harbored the c.1906G>C mutation. Eleven other mutations (2 nonsense, 3 splice site and 6 small deletions) were detected. Three of the mutations are novel. No gross deletions or insertions were detected. This is the first report that characterizes the profile of HNPCC in a cohort of patients in Israel. Tumor testing indicated that the 3 main MMR genes are involved, and that mutation spectrum is broad.

Cancer risks in carriers of the BRCA1/2 Ashkenazi founder mutations.

BACKGROUND: The risks for cancers other than breast (BC) or ovarian (OC) cancer in breast cancer gene 1 and 2 (BRCA1/2) mutation carriers were elevated in studies of carrier families. However, case-control studies did not confirm this observation. OBJECTIVE: To compare the risks for other cancers in BRCA1/2 mutation carriers and non-carriers, all affected with BC and/or OC. Both groups share risk modifiers of BC/OC, which enabled assessment of the role of BRCA1/2 mutations. METHODS: 1098 Ashkenazi Jewish women affected with BC and/or OC were ascertained during 1995-2003; molecular testing revealed 229 BRCA1 and 100 BRCA2 carriers and 769 non-carriers. COX proportional hazard models were used to evaluate the risk of other cancers. Analyses were conducted including all other cancers or only those diagnosed after BC/OC diagnosis. RESULTS: The HRs for any other cancer were 2.6 (95% CI 1.7 to 4.2, p<0.001) and 1.8 (95% CI 0.95 to 3.6, p = 0.07) in BRCA1 and BRCA2 carriers, respectively. The corresponding colon cancer HRs were 3.9 (95% CI 1.3 to 12.1, p = 0.02) and 2.3 (95% CI 0.5 to 11.3, p = 0.3) in BRCA1 and BRCA2 carriers. The HR for lymphoma was 11.9 (95% CI 3.1 to 46.2, p = 0.001) in BRCA2 carriers. Risk estimates for other cancers after the onset of BC/OC were similar. CONCLUSION: A 2.5-fold increase in any other cancer and a fourfold risk of colon cancer were found among BRCA1 carriers. The corresponding HRs in BRCA2 carriers were non-significant, except for the markedly elevated risk of lymphoma. These results suggest a role for BRCA1/2 mutations in colorectal cancer risk in a subgroup of BC/OC-affected carriers.

[Can we improve the content and quality of information delivered prior to amniocentesis?].

INTRODUCTION: Amniocentesis is a procedure often used for pregnant women, as an important tool to identify chromosomal abnormalities, trisomy 21 being the main one. Amniocentesis may involve certain possible complications, the most prevalent is miscarriage. In order to make an informed decision, a woman must understand some statistical information regarding the risks and benefits of management options. OBJECTIVES: The objective of this work was to examine women's understanding of risks and benefits before amniocentesis and the effect of an educational intervention on this understanding. METHODS: Women applying for amniocentesis at Hadassah Ein-Kerem clinics were handed a questionnaire. The questionnaire examined several aspects of knowledge relevant to an informed decision about the amniocentesis. An intervention was designed to improve women's understanding before amniocentesis: an information handout was sent home to 48 women who had signed up for amniocentesis. The level of knowledge was compared between women who did and did not receive the information handout. RESULTS: There was no difference in the level of general understanding between the two groups. When the level of understanding was broken down to its specific components, it became apparent that the only improvement achieved was concerning the risk of miscarriage from the amniocentesis. CONCLUSIONS: Information delivered before amniocentesis is challenging and further research is needed in order to develop educational material that would improve women's understanding of risks and benefits of the procedure.

A novel BRCA-1 mutation in Arab kindred from east Jerusalem with breast and ovarian cancer.

BACKGROUND: The incidence of breast cancer (BC) in Arab women is lower compared to the incidence in the Jewish population in Israel; still, it is the most common malignancy among Arab women. There is a steep rise in breast cancer incidence in the Arab population in Israel over the last 10 years that can be attributed to life style changes. But, the younger age of BC onset in Arab women compared with that of the Jewish population is suggestive of a genetic component in BC occurrence in that population. METHODS: We studied the family history of 31 women of Palestinian Arab (PA) origin affected with breast (n = 28), ovarian (n = 3) cancer. We used denaturing high performance liquid chromatography (DHPLC) to screen for mutations of BRCA1/2 in 4 women with a personal and family history highly suggestive of genetic predisposition. RESULTS: A novel BRCA1 mutation, E1373X in exon 12, was found in a patient affected with ovarian cancer. Four of her family members, 3 BC patients and a healthy individual were consequently also found to carry this mutation. Of the other 27 patients, which were screened for this specific mutation none was found to carry it. CONCLUSION: We found a novel BRCA1 mutation in a family of PA origin with a history highly compatible with BRCA1 phenotype. This mutation was not found in additional 30 PA women affected with BC or OC. Therefore full BRCA1/2 screening should be offered to patients with characteristic family history. The significance of the novel BRCA1 mutation we identified should be studied in larger population. However, it is likely that the E1373X mutation is not a founder frequent mutation in the PA population.

Carrier screening for Gaucher disease: lessons for low-penetrance, treatable diseases.

CONTEXT: The aim of carrier screening is to prevent severe, untreatable genetic disease by identifying couples at risk before the birth of an affected child, and providing such couples with options for reproductive outcomes for affected pregnancies. Gaucher disease (GD) is an autosomal recessive storage disorder, relatively frequent in Ashkenazi Jews. Carrier screening for GD is controversial because common type 1 GD is often asymptomatic and effective treatment exists. However, screening is offered to Ashkenazi Jews worldwide and has been offered in Israel since 1995. OBJECTIVE: To examine the scope and outcomes of nationwide GD screening. DESIGN, SETTING, AND PARTICIPANTS: All Israeli genetic centers provided data on the number of individuals screened for GD, the number of carriers identified, the number of carrier couples identified, and the mutations identified in these couples between January 1, 1995, and March 31, 2003. Carrier couples were interviewed via telephone between January 21, 2003, and August 31, 2004, using a structured questionnaire for relevant outcome measures. MAIN OUTCOME MEASURES: Screening scope (number of testing centers, tested individuals, and carrier couples), screening process (type of pretest and posttest consultations), and screening outcomes (utilization of prenatal diagnosis and pregnancy terminations). RESULTS: Between January 1, 1995, and March 31, 2003, 10 of 12 Israeli genetic centers (83.3%) offered carrier screening. Carrier frequency was 5.7%, and 83 carrier couples were identified among an estimated 28,893 individuals screened. There were 82 couples at risk for offspring with type 1 GD. Seventy of 82 couples (85%) were at risk for asymptomatic or mildly affected offspring and 12 of 82 couples (15%) were at risk for moderately affected offspring. At postscreening, 65 interviewed couples had 90 pregnancies, and prenatal diagnosis was performed in 68 pregnancies (76%), detecting 16 fetuses with GD (24%). Pregnancies were terminated in 2 of 13 fetuses (15%) predicted to be asymptomatic or mildly affected and 2 of 3 fetuses (67%) with predicted moderate disease. There were significantly fewer pregnancy terminations in couples who in addition to genetic counseling had medical counseling with a GD expert (1 of 13 [8%] vs 3 of 3 with no medical counseling [100%], P = .007). CONCLUSIONS: In this study of GD screening among Ashkenazi Jewish couples in Israel, most couples did not terminate affected pregnancies, although screening was associated with a few pregnancy terminations. The main possible benefit was providing couples with knowledge and control. The divergence of these outcomes from stated goals of screening programs is likely to confront carrier screening programs for low-penetrance diseases.

[A new oncogenetic service of counseling and diagnosing for hereditary non-polyposis colorectal cancer (HNPCC)].

BACKGROUND: Hereditary non-polyposis colorectal cancer (HNPCC) is an autosomal dominant cancer predisposition syndrome associated with a high risk for colorectal cancer (up to 80%), endometrial cancer (up to 60%), and increased risk for other malignancies, mostly ovarian and urinary system tumors. HNPCC is caused by a germline mutation in one of the mismatch repair (MMR) genes, mainly hMLH1, hMSH2 and hMSH6. The tumors present with microsatellite instability (MSI) associated with loss of heterozygosity of the affected gene, and with loss of expression of the gene product. Diagnosis of HNPCC involves tumor testing for MSI, immunohistochemistry staining and germ line mutation analysis of the suspected gene. Proper genetic counseling is based on the synthesis of the clinical, pathological and molecular data. Directed surveillance shows significant reduction in colon cancer incidence, cancer mortality and overall mortality among HNPCC patients. GOAL: To establish a multidisciplinary service for patients suspected of having HNPCC. METHODS: We have established a service which is based on tight collaboration between clinical departments and laboratories. The clinical work-up was conducted by a special oncogenetic clinic and the laboratory service consisted of tissue testing for MSI and immunohistochemistry, denaturing high performance liquid chromatography (DHPLC) for suspected genes, and mutation testing. RESULTS: The efficiency of detection of patients with HNPCC was high, completed in a multistep process. In the first year of our collaborative work, we have provided genetic counseling to over 100 families and performed suitable tests for 46 families. Among them we have identified more than 16 families with HNPCC; 4 showed absence of hMLH1, 1 showed absence of hMSH6, and 11 showed absence of hMSH2. All tumors that showed MSI also showed absence of either one of the three MMR proteins. We present the clinical, pathological and molecular features of our patients and discuss the implication of this data on future recommendations.

Acceptance of preventive surgeries by Israeli women who had undergone BRCA testing.

Using a specially constructed questionnaire, the effect of BRCA test results for the Jewish founder mutations and genetic counseling on women's attitudes towards and acceptance of preventive surgeries was evaluated. The subjects consisted of 99 women 43% of whom were found to be carriers as opposed to 57%--non-carriers. After learning of their genetic status, 94% of the carriers and 28% of the non-carriers declared having positively considered the option of preventive oophorectomy. However, only about 25% of the carriers and 4.5% of the non-carriers had positively considered the option of preventive mastectomy. In practice, 78% of the carriers and 18% of the non-carriers who proved to be eligible for these procedures underwent preventive oophorectomy compared with 19% of carriers and 1.8% of non-carriers who underwent preventive mastectomy. Almost all carriers, as well as a majority of the non-carriers, who finally opted for the preventive surgeries did so after learning the result of their genetic test. The different attitudes toward the two surgeries were found to be based on varied beliefs regarding the two procedures. Preventive oophorectomy was perceived as being more acceptable to women than preventive mastectomy both from an attitudinal as well as practical aspect. These differences may be the result of cultural factors, of women's trust in the ability of screening tests to prevent morbidity and/or mortality, of the effect of the surgeries on body image and of different counseling protocols.

A novel MLH1 mutation harbored as a germ line aberration by a young woman of an HNPCC-like family and exhibited by a CML patient when occurring prior to the initiation of the blast phase concomitant with a c-MYC amplification.

Germ line mutations in the MLH1 and MSH2 genes account for the majority of hereditary nonpolyposis colorectal cancer (HNPCC) families. Here, we describe a family that does not meet the international criteria for HNPCC, of which a young woman harbors a missense mutation (D132H). This novel germ line mutation has not previously been reported. Of the mismatch repair (MMR) genes, MLH1 has been shown to play an important role in hematologic malignancies. The novel mutation was also revealed to be a somatic aberration occurring prior to the initiation of the blast phase in a chronic myelogenous leukemia (CML) patient. Among the possible MLH1 partners involved in signaling MMR or apoptosis is the proto-oncogene c-MYC, which is closely related to cellular proliferation. We further revealed a concomitant c-MYC dramatic amplification in the CML-MLH1-mutation carrier patient, also occurring at the pre-blast phase. Our data contribute further to characterizing the mutational spectrum of the MLH1 gene. Furthermore, given the role of c-MYC and its interaction with MLH1, taken together with the mutational status of both genes revealed at the pre-blast phase in the CML patient, a plausible increased genetic instability might be expected to take place, possibly contributing to blast triggering. Our results may provide additional insight into the complex interplay between the MMR system and other cellular pathways.

[Prophylactic oophorectomy among carriers of BRCA1/2 mutations--demographic and pathologic data].

BACKGROUND: During the past few years, the genes BRCAI and BRCA2 were cloned. Mutations in each gene are responsible for the syndrome of familial breast and ovarian carcinoma. Among women who carry such a mutation, there is a 56%-80% life-time risk of developing breast cancer and a 16%-60% risk of developing ovarian cancer. Recently, it has been proven that prophylactic mastectomy and/or oophorectomy might reduce such risks of developing cancer. Neither of these treatments offers full protection and furthermore, compliance of carriers is partial, considering the physical and mental consequences of such treatment. GOALS AND METHODS: This study describes the sociodemographic profile of 30 healthy carriers of BRCA1/2 mutations that underwent prophylactic salpingo-oophorectomy. We also examined the pathological specimens and point out the ratio of significant pathological findings, especially the presence of cancer. The women are being followed-up at Hadassah Medical Center, Jerusalem. RESULTS: Pathological examination of the ovaries and fallopian tubes of 30 healthy carriers of BRCA1/2 mutations who underwent prophylactic salpingo-oophorectomy revealed tumor in three cases (10%). Two tumors were in the ovaries and one in the fallopian tube. One of these tumors was in an advanced stage and two were small and confined to the organ. CONCLUSIONS: Based on the above results, we noted that salpingo-oophorectomy, despite being quite a radical preventive method, might offer protection for the carriers against life-threatening silently-developing cancer. We found cancer in 10% (3) of the women, and in two of these cases, prophylactic salpingo-oophorectomy became the definitive treatment for a small occult tumor.

An Ashkenazi founder mutation in the PKHD1 gene.

Autosomal recessive polycystic kidney disease (ARPKD) is usually detected late in pregnancies in embryos with large echogenic kidneys accompanied by oligohydramnios. Hundreds of private pathogenic variants have been identified in the large PKHD1 gene in various populations. Yet, because of the large size of the gene, segregation analysis of microsatellite polymorphic markers residing in the PKDH1 locus has commonly been utilized for prenatal diagnosis. Keeping in mind the limitations of this strategy, we utilized it for testing 7 families with affected fetuses or newborns, of which in 5 at least one parent was Ashkenazi, and identified that the same haplotype was shared by the majority of the Ashkenazi parents (7/9). This led us to suspect that they carry the same founder mutation. Whole Exome analysis of DNA from a fetus of one of the families detected an already known pathogenic variant c.3761_3762delCCinsG, an indel variant resulting in frameshift (p.Ala1254GlyfsX49). This variant was detected in 9 parents (5 families), of them 7 individuals were Ashkenazi and one Moroccan Jew who shared the same haplotype, and one Ashkenazi, who carried the same variant on a recombinant haplotype. Screening for this variant in 364 Ashkenazi individuals detected 2 carriers. These findings suggest that although c.3761_3762delCCinsG is considered one of the frequent variants detected in unrelated individuals, and was thought to have occurred independently on various haplotypes, it is in fact a founder mutation in the Ashkenazi population.

Genetic screening in patients with Retinoblastoma in Israel.

Retinoblastoma (Rb) is a childhood tumor (~1 in 20,000 live births) developing in the retina due to mutations in the RB1 gene. Identification of the oncogenic mutations in the RB1 gene is important for the clinical management and for genetic counseling to families with a child or a parent affected with the tumor. Here we present our experience in detecting the pathogenic mutations in blood samples, from 150 unrelated Rb patients and highlight the relevant counseling issues. Mutation screening in the RB1 gene was based on Sanger sequencing, mosaicism of recurrent CpG transition mutations was detected by allele specific PCR and multiplex ligation dependent probe amplification for detecting of large deletions/duplications. The overall detection rate of mutations in our cohort was 55% (82/150). In the familial cases it was 100% (17/17), in bilateral and unilateral-multifocal sporadic cases 91% (50/55), and in the unilateral sporadic cases 19% (15/78). Nonsense mutations and small deletions or insertions that results in transcripts with premature termination codons that are subject to nonsense mediated decay were the most frequent, detected in 50/82 (61%) of the patients. The rest were large deletions detected in 14/82 (17%), splice site mutations detected in 11/82 (13%), missense mutations in four patients and mutations in the promoter sequence in three patients. Mutation mosaicism ranging from 10 to 30% was detected by allele specific PCR in ten patients, 9% (5/55) of patients with bilateral tumor and 33% (5/15) of the patients with unilateral tumor. In three patients rare variants were detected as the only finding which was also detected in other healthy family members. Allele specific amplification of recurrent mutations raises in our cohort the identification rate from 82 to 91% in the sporadic bilateral cases and from 13 to 19% in the unilateral sporadic cases. Most mosaic cases could not be identified by Sanger sequencing and therefore screening for recurrent CpG transition mutations by allele specific amplification is of utmost importance. Molecular screening is important for the genetic counseling regarding the risk for tumor development and the relevance for prenatal diagnosis but in several families is accompanied by detecting rare variants that might be rare polymorphisms or low penetrant mutations.

Whole Exome Sequencing Reveals Mutations in Known Retinal Disease Genes in 33 out of 68 Israeli Families with Inherited Retinopathies.

Whole exome sequencing (WES) is a powerful technique for identifying sequence changes in the human genome. The goal of this study was to delineate the genetic defects in patients with inherited retinal diseases (IRDs) using WES. WES was performed on 90 patient DNA samples from 68 families and 226 known genes for IRDs were analyzed. Sanger sequencing was used to validate potential pathogenic variants that were also subjected to segregation analysis in families. Thirty-three causative mutations (19 novel and 14 known) in 25 genes were identified in 33 of the 68 families. The vast majority of mutations (30 out of 33) have not been reported in the Israeli and the Palestinian populations. Nine out of the 33 mutations were detected in additional families from the same ethnic population, suggesting a founder effect. In two families, identified phenotypes were different from the previously reported clinical findings associated with the causative gene. This is the largest genetic analysis of IRDs in the Israeli and Palestinian populations to date. We also demonstrate that WES is a powerful tool for rapid analysis of known disease genes in large patient cohorts.