Israel Medical Association Journal

Germline pathogenic variants (PVs) in the RET proto-oncogene (OMIM 164761) are associated with a diverse phenotype based on the type of PV. Gain-of-function (GOF) PVs are associated with the highly penetrant multiple endocrine neoplasia type 2 (MEN2-OMIM 171400), which are hallmarked by an increased risk for developing medullary thyroid cancer (MTC), pheochromocytoma, and parathyroid adenomas. Loss-of-function (LOF) RET PVs are associated with incompletely penetrant Hirschsprung's disease (HSCR OMIM 142623), which are pathologically characterized by the absence of enteric ganglia affecting the distal colon and clinically manifest as neonatal intestinal obstruction. Despite anecdotal reports of familial clustering of neoplasms in HSCR families, mostly MEN2-associated tumors [1,2], HSCR is not considered to be associated with an increased risk for developing cancer [3]. We report on a family with an unusual multigenerational solid tumor phenotype and severe HSCR phenotype with a LOF RET PV.

Background: Population screening for the BRCA mutations in Ashkenazi Jewish women was recently implemented in Israel and is expected to lead to a 10-fold increase in the diagnosis of asymptomatic carriers. Performing the screening follow-up within multidisciplinary dedicated clinics for carriers is recommended for early detection and risk reduction.

Objectives: To determine the availability, capacity, and practices of dedicated screening clinic for BRCA carriers in Israel.

Methods: A telephone-based survey of all public hospitals in Israel was conducted October 2020 to August 2021 to determine whether they had a dedicated clinic. Dedicated clinics were defined as multidisciplinary screening clinics offering at least breast and gynecological screening and risk reducing services on site. The clinic director or nurse navigator answered a questionnaire about screening practices followed by a semi-structured interview.

Results: Of the ten dedicated BRCA clinics found in Israel, nine participated. Approximately 4500 BRCA carriers are currently being followed. No specialized clinics are available in the southern district or in the northernmost half of the northern district of Israel, leading to a disparity between periphery and center. Screening recommendations, although asserted as adhering to international guidelines, vary among clinics including age at initiating of clinical exam, use of adjunct imaging modalities, and follow-up during lactation and after risk reducing surgery.

Conclusions: There is a suboptimal distribution of dedicated clinics for BRCA carriers in Israel. Nationally centralized attempt to create guidelines that will unify screening practices is warranted, especially considering the expected increase in demand.

Background: Biallelic BLM gene mutation carriers are at an increased risk for cancer, including colorectal cancer (CRC). Whether heterozygous BLM gene mutations confer an increased cancer risk remains controversial.

Objectives: To evaluate CRC and endometrial cancer risk in BLM heterozygous mutation carriers.

Methods: Jewish Ashkenazim at high risk for colon or endometrial cancer and endometrial cancer cases unselected for family history were genotyped for the BLM^Ash predominant mutation.

Results: Overall, 243 high-risk individuals were included: 97 men CRC patients (55.12 ± 12.3 years at diagnosis), 109 women with CRC (56.5 ± 13.7 years), 32 women with endometrial cancer (58.25 ± 13.4 years) and 5 women with both CRC and endometrial cancer. In addition, 120 unselected Ashkenazi women with endometrial cancer (64.2 ± 11.58 years) were genotyped. The BLM^Ash mutation was present in 4/243 (1.65%) high-risk patients; 2 CRC (0.97%) 2 endometrial cancer (5.4%), and 1/120 unselected endometrial cancer patients (0.84%). Notably, in high-risk cases, BLM^Ash mutation carriers were diagnosed at a younger age (for CRC 47.5 ± 7.8 years; P = 0.32 ; endometrial cancer 49.5 ± 7.7 years; P = 0.36) compared with non-carriers.

Conclusions: Ashkenazi high risk CRC/endometrial cancer, and women with endometrial cancer have a higher rate of BLM^Ash heterozygous mutation compared with the general population. BLM^Ash heterozygous mutation carriers are diagnosed with CRC and endometrial cancer at a younger age compared with non-carriers. These observations should be validated and the possible clinical implications assessed.

Background: Automated breast volumetric sonography (ABVS) is a new technology with various possible applications.

Objectives: To compare ABVS and breast magnetic resonance imaging (MRI) in the surveillance of women with BRCA1/2 gene mutation carriers.

Methods: We conducted a prospective study in Jewish female BRCA1/2 mutation carriers who underwent breast MRI and ABVS. The results of both exams performed 6 months apart or less, and relevant clinical data, were reviewed. The BIRADS results were divided into three subgroups according to subsequent expected management: BIRADS 1-2 (normal study), BIRADS 3 (probably benign finding), and BIRADS 4 and 5 (suspicious findings). BIRADS 0 and 6 scores were excluded from the study. Distribution of ABVS and MRI BIRADS scores were compared using McNemar's test, and concordance was calculated using the Cohen kappa test.

Results: Overall, 68 women, 40 BRCA1 and 28 BRCA2 mutation carriers, age range 26–69 (mean 44.55 ± 12.1 years), underwent 79 paired ABVS and MRI examinations. McNemar's test calculations showed no significant difference between MRI and ABVS BIRADS score distribution. Cohen’s kappa test resulted in k = 0.158, an agreement that can be described as only "slight agreement" between both modalities. Of 14 discordant cases there was one cancer, revealed by MRI and not by ABVS performed 6 months prior to MRI.

Conclusions: ABVS showed slight agreement with MRI in BRCA1/2 mutation carriers. These preliminary results on a small group of healthy high risk patients suggest that the diagnostic abilities of ABVS are inferior to MRI. Further studies encompassing larger groups are needed.

 

Background: Germline mutations in BRCA1 and BRCA2 genes account for only 20–40% of familial breast cancer cases. The CHEK2 gene encodes a checkpoint kinase, involved in response to DNA damage, and hence is a candidate gene for breast cancer susceptibility. Indeed, the CHEK2*1100delC truncating mutation was reported in a subset of mostly North European breast cancer families. The rate of the CHEK2*1100delC variant in the Ashkenazi* Jewish population was reported to be 0.3%.

Objectives: To evaluate whether CHEK2 germline mutations contribute to a breast cancer predisposition in Ashkenazi-Jewish high risk families.

Methods: High risk Ashkenazi Jewish women, none of whom was a carrier of the predominant Jewish mutations in BRCA1/BRCA2, were genotyped for germline mutations in the CHEK2 gene by exon-specific polymerase chain reaction followed by denaturing gradient gel electrophoresis and sequencing of abnormally migrating fragments.

Results: Overall, 172 high risk women were genotyped: 75 (43.6%) with breast cancer (average age at diagnosis 49.6 ± 9.6 years, mean ± SD) and 97 asymptomatic individuals (age at counseling 48.3 ± 8.2 years). No truncating mutations were noted and four previously described missense mutations were detected (R3W 1.2%, I157T 1.2%, R180C 0.6% and S428F 5%), one silent polymorphism (E84E 20.5%) and one novel missense mutation (Y424H 1.2%). Segregation analysis of the I157T and S428F mutations (shown to affect protein function) with the cancer phenotype showed concordance for the CHK2*I157T mutation, as did two of three families with the CHK2*S428F mutation.

Conclusions: CHEK2 missense mutations may contribute to breast cancer susceptibility in Ashkenazi Jews.

Background: The contribution of the abnormal DNA mismatch repair system to non-small cell lung cancer tumorigenesis is controversial and has not been reported in Jewish Israeli patients. Similarly, the involvement of 3p deletions in NSCLC[1] in the same population has not been assessed.

Objectives: To assess the contribution of the DNA-MMR[2] system to NSCLC pathogenesis by analyzing microsatellite instability, and evaluate loss of heterozygosity at 3p rates in Israeli NSCLC patients.

Methods: Paired DNA from tumorous and non-tumorous tissue was extracted, and genotyping for MSI[3] determination was carried out using the five Bethesda markers and for determining LOH[4] two 3p markers were used. Genotyping was performed using polymerase chain reaction amplification and size separation on an ABI semiautomatic DNA sequencer, and the allelic patterns of tumorous and non-tumorous tissue were compared.

Results: Forty-four NSCLCs from 35 smokers and 9 non-smokers were analyzed, with 26 of the 44 (59%) at stage I disease. Using five microsatellite markers (D17S250, D5S346, D2S123, BAT-25, BAT-26) (known as Bethesda markers) for MSI determination, 6 of the 44 tumors (13.6%) exhibited MSI in at least one marker. Similarly, genotyping for LOH at chromosome 3p was performed using two markers (D3S4103, D3S1234) located at 3p14.2 l. With D3S4103, 33 of the 44 patients successfully analyzed were homozygous and therefore non-informative with respect to LOH. Using D3S1234, 33 of 36 patients (91.7%) were heterozygous, and 23 of these individuals' tumors (69.7%) displayed LOH. Unexpectedly, 4 of 33 tumors (12.1%) genotyped by D3S4103, and 16 of 36 tumors (44.5%) genotyped by D3S1234 showed a pattern of MSI, even though only one of these tumors showed a similar pattern when genotyped with the five consensus markers. Overall, 23 of 44 tumors (52.3%) demonstrated MSI on at least one marker, and 5 of these 23 tumors (21.7%) had MSI on two or more markers.

Conclusions: MSI using 3p markers and not the Bethesda markers occurs at a high rate and in early stages in Jewish NSCLC patients.

Background: The precise genes involved in conferring prostate cancer risk in sporadic and familial cases are not fully known.

Objectives: To evlauate the genetic profile within several candidate genes of unselected prostate cancer cases and to correlate this profile with disease parameters.

Methods: Jewish Israeli prostate cancer patients (n=224) were genotyped for polymorphisms within candidate genes: p53, ER, VDR, GSTT1, CYP1A1, GSTP1, GSTM1, EPHX and HPC2/ELAC2, followed by analysis of the genotype with relevant clinical and pathologic parameters.

Results: The EPHX gene His113 allele was detected in 21.4% (33/154) of patients in whom disease was diagnosed above 61 years, compared with 5.7% (4/70) in earlier onset disease (P < 0.001). Within the group of late-onset disease, the same allele was noted in 5.5% (2/36) with grade I tumors compared with 18% (34/188) with grade II and up (P = 0.004). All other tested polymorphisms were not associated with a distinct clinical or pathologic feature in a statistically significant manner.

Conclusions: In Israeli prostate cancer patients, the EPHX His113 allele is seemingly associated with a more advanced, late-onset disease. These preliminary data need to be confirmed by a larger and more ethnically diverse study.

Background: Genes that confer mild or moderate susceptibility to breast cancer may be involved in the pathogenesis of sporadic breast cancer, modifying the phenotypic expression of mutant BRCA1/BRCA2 alleles. An attractive candidate is the insulin-like growth factor I, a known mitogen to mammary ductal cells in vivo and in vitro, whose serum levels were reportedly elevated in breast cancer patients.

Objective: To evaluate the contribution of the IGF-1 gene polymorphism to breast cancer risk by genotyping for a polymorphic allele size in breast cancer patients and controls.

Methods: We analyzed allele size distribution of the polymorphic CA repeat upstream of the IGF-I gene in 412 Israeli Jewish women: 268 women with breast cancer (212-sporadic and 56 carriers of either a BRCA1:or BRCA2 mutation), and 144 controls. Genotyping was accomplished by radioactive polymerase chain reaction of the relevant genomic region and size fractionation on polyacrylamide gels with subsequent auloradiography,

Results: Among women with breast cancer, with or without BRCA germline mutations, 196 and 198 basepair alleles were present in 4.7% (25/536 alleles), compared with 9% (26/288) controls (P = 0.02). This difference was more pronounced and significant in the non-Ashkenazi population. Conversely, the smaller size allele (176 bp) was present in the breast cancer group only {3/536, 0.6%).

Conclusions: The IGF-I polymorphism may serve as a marker for breast cancer risk in the general Jewish population, in particular non-Ashkenazi Jews, but extension and confirmation of these preliminary data are needed.
 

Background: Genetic factors have been shown to play a major role in the development of peak bone mass, with hereditability accounting for about 50-85% of the variance in bone mass. Numerous candidate genes were proposed to be involved in osteoporosis, but the precise genes and their relative contribution remain unknown.

Objectives: To gain insight into the genetic basis of idiopathic low bone mineral density in Israeli patients by analyzing the impact of two candidate genes: polymorphism of the vitamin D receptor gene and polymorphism A986s in the calcium-sensing receptor gene.

Methods: We analyzed 86 Jewish Israeli patients with LBMD[1]: 38 premenopausal women and 48 men, and compared the allelic pattern distribution with that of the general population (126 men and 112 women). Genotyping of the VDR[2] gene was performed in three polymorphic sites using restriction enzymes, and allelic analysis of A986s polymorphism in the CaSR[3] gene was performed using the denaturing gradient gel electrophoresis technique.  

Reaults: In LBMD women the distributions of VDR alleres in Apal polymorphism were AA=7/28, Aa=16/28 and aa=5/28; in TaqI polymorphism TT=10/31, Tt=16/31 and tt=5/31; and in BsmI polymorphism BB=7/32, Bb=14/32 and 11/32. In LBMD men the distributions were AA=17/39, Aa=21/39 and aa=1/39; in TaqI polymorphism TT=12/42, Tt=23/42 and tt=7/42; and in BsmI polymorphism BB=12/41 Bb=18/41 and bb=11/41. The distributions of all these polymorphisms in the control groups were not significantly different. Adjusting for the independent age and gender parameters confirmed that these three polymorphisms of the VDR gene did not have a significant effect on bone mineral density. Thirty percent (24/79) of LBMD patients of either sex displayed heterozygosity of the CaSR A986s polymorphism, compared with 40 of 203 controls (19.7%) (P=0.059). Adjusting for age and gender in these patients revealed a significant difference in the femoral neck BMD[4] between homozygotes and heterozygotes (P=0.002). The age at menarche of the LBMD women was found to predict 61% of the variance of femoral neck BMD.

Conclusions: In Israeli Jewish men and premenopausal women VDR gene alleles do not seem to be associated with lower lumbar spine or femoral neck BMD. A trend towards heterozygosity for a CaSR polymorphism missense mutation was noted in the LBMD patients. Age at menarche in the LBMD women was found to be an important predictor of BMD. A significant difference was found between LBMD women and healthy control women towards heterozygosity for a CaSR polymorphism, as well between homozygotes and heterozygotes for a CaSR polymorphism in BMD. The significance of these findings and their applicability to a larger population awaits further studies.

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Background: The Bloom syndrome gene, BLM, was mapped to 15q26.1 and its product was found to encode a RecQ DNA helicase. The Fanconi anemia complementation group C gene was mapped to chromosome 9q22.3, but its product function is not sufficiently clear. Both are recessive disorders associated with an elevated predisposition to cancer due to genomic instability. A single predominant mutation of each disorder was reported in Ashkenazi Jews: 2281delATCTGAinsTAGATTC for Bloom syndrome (BLM-ASH) and IVS4+4A®T for Fanconi anemia complementation group C.

Objectives: To provide additional verification of the mutation rate of BLM and FACC[1] in unselected Ashkenazi and non-Ashkenazi populations analyzed at the Sheba Medical Center, and to trace the origin of each mutation.

Methods: We used polymerase chain reaction to identify mutations of the relevant genomic fragments, restriction analysis and gel electrophoresis. We then applied the Pronto^TM kit to verify the results in 244 samples and there was an excellent match.

Results: A heterozygote frequency of 1:111 for BLM-ASH and 1:92 for FACC was detected in more than 4,000 participants, none of whom reported a family history of the disorders. The Pronto^TM kit confirmed all heterozygotes. Neither of the mutations was detected in 950 anonymous non-Ashkenazi Jews. The distribution pattern of parental origin differed significantly between the two carrier groups, as well as between each one and the general population.

Conclusions: These findings as well as the absence of the mutations in non-Ashkenazi Jews suggest that: a) the mutations originated in the Israelite population that was exiled from Palestine by the Roman Empire in 70 AD and settled in Europe (Ashkenazi), in contrast to those who remained; and b) the difference in origin distribution of the BS[2] and FACC mutations can be explained by either a secondary migration of a subgroup with a subsequent genetic drift, or a separate geographic region of introduction for each mutation.

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[1] FACC = Fanconi anemia complementation group C