Tu1893 MUTYH Mutations and Variants in Jews of North-African Origin With or Without Minimal Colorectal Adenomatous Polyposis

Abstract

Background: Israeli-Jews of North-African origin are ~ 1/6 of the Israeli population, and have been considered as a low-risk population for colorectal cancer (CRC). In recent years CRC risk has been increased in this population. However, the contributing genetic susceptibility is currently unknown. Mutations in the MUTYH gene, which cause multiple colorectal adenomas and early onset colon cancer, might play a role in their increased CRC risk. Objectives: Evaluate frequency and types of MUTYH mutations and variants in a population of Jews fromNorth-African origin having colorectal adenomas and early onset CRC. Methods: The study population included North-African Jews having colonoscopy between 2007-12, having ≥3 colorectal adenomas and/or CRC, and were matched to controls having normal colonoscopy. Germ-line DNA was tested for a panel of 6 MUTYH mutations or variants and Sanger sequencing of the entire MUTYH gene for heterozygotes. Familial Adenomatous Polyposis (FAP) and Lynch Syndrome were excluded in the relevant cases. Results: 99 subjects, 69 with adenomas had MUTYH analysis; 19 (27.5%) had mutations or variants identified. In adenoma patients there were eight homozygotes or compound heterozygotes to either Y179C or G396D mutations: all had >10 adenomas and 5 had familial neoplasia. Six others were heterozygotes to only one mutation: 4 with 10 adenomas; 5 had familial neoplasia and 3 a neoplasm. Four subjects found as S512F heterozygotes: two had 10 adenomas. Two heterozygotes had the Q324H variant. In 23 non-adenoma controls: 1 had the S512F another the L417M variant, another the R509C variant and 16 the Q324H variant. Conclusions: MUTYH mutations are prevalent among Jews of North-African origin having colonic adenomas and/or early onset CRC. The clinical phenotype can be associated with only few adenoma and with family and personal history of cancer similar to sporadic CRC. The S512F mutation appears to be pathogenic, the Q324H a frequent variant that was not found to be associated with adenomas. The findings suggest MUTYH evaluation in these patients with even few adenomas, and need to follow-up heterozygotes carriers for CRC.