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עמוד בית
Thu, 30.05.24

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June 2017
Hagit Schayek PhD, Yael Laitman MSc, Lior H Katz MD, Elon Pras MD, Liat Ries-Levavi PhD, Frida Barak MD and Eitan Friedman MD PhD

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 BLMAsh 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 BLMAsh 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, BLMAsh 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 BLMAsh heterozygous mutation compared with the general population. BLMAsh 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.

December 2007
H.N. Baris, I. Kedar, G.J. Halpern, T. Shohat, N. Magal, M.D. Ludman and M. Shohat

Background: Fanconi anemia complementation group C and Bloom syndrome, rare autosomal recessive disorders marked by chromosome instability, are especially prevalent in the Ashkenazi* Jewish community. A single predominant mutation for each has been reported in Ashkenazi Jews: c.711+4A→T (IVS4 +4 A→T) in FACC[1] and BLMAsh in Bloom syndrome. Individuals affected by both syndromes are characterized by susceptibility for developing malignancies, and we questioned whether heterozygote carriers have a similarly increased risk.

Objectives: To estimate the cancer rate among FACC and BLMAsh carriers and their families over three previous generations in unselected Ashkenazi Jewish individuals.

Methods: We studied 42 FACC carriers, 28 BLMAsh carriers and 43 controls. The control subjects were Ashkenazi Jews participating in our prenatal genetic screening program who tested negative for FACC and BLMAsh. All subjects filled out a questionnaire regarding their own and a three-generation family history of cancer. The prevalence rates of cancer among relatives of FACC, BLMAsh and controls were computed and compared using the chi-square test.

Results: In 463 relatives of FACC carriers, 45 malignancies were reported (9.7%) including 10 breast (2.2%) and 13 colon cancers (2.8%). Among 326 relatives of BLMAsh carriers there were 30 malignancies (9.2%) including 7 breast (2.1%) and 4 colon cancers (1.2%). Controls consisted of 503 family members with 63 reported malignancies (12.5%) including 11 breast (2.2%) and 11 colon cancers (2.2%).

Conclusions: We found no significantly increased prevalence of malignancies among carriers in at least three generations compared to the controls.






* Jews of East European origin



[1] FACC = Fanconi anemia complementation group C


February 2002
Leah Peleg, PhD, Rachel Pesso, PhD, Boleslaw Goldman, MD, Keren Dotan, Merav Omer, Eitan Friedman, MD, PhD, Michal Berkenstadt, PhD, Haike Reznik-Wolf, PhD and Gad Barkai, MD

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 ProntoTM 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 ProntoTM 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


[2] BS = Bloom syndrome

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