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We report an autosomal recessive, multi-organ tumor predisposition syndrome, caused by bi-allelic loss-of-function germline variants in the base excision repair (BER) gene MBD4. We identified five individuals with bi-allelic MBD4 variants within four families and these individuals had a personal and/or family history of adenomatous colorectal polyposis, acute myeloid leukemia, and uveal melanoma. MBD4 encodes a glycosylase involved in repair of G:T mismatches resulting from deamination of 5'-methylcytosine. The colorectal adenomas from MBD4-deficient individuals showed a mutator phenotype attributable to mutational signature SBS1, consistent with the function of MBD4. MBD4-deficient polyps harbored somatic mutations in similar driver genes to sporadic colorectal tumors, although AMER1 mutations were more common and KRAS mutations less frequent. Our findings expand the role of BER deficiencies in tumor predisposition. Inclusion of MBD4 in genetic testing for polyposis and multi-tumor phenotypes is warranted to improve disease management.

Original publication

DOI

10.1016/j.ajhg.2022.03.018

Type

Journal article

Journal

American journal of human genetics

Publication Date

05/2022

Volume

109

Pages

953 - 960

Addresses

Institute of Cancer and Genomic Sciences, College of Medical and Dental Science, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK.

Keywords

Genomics England Research Consortium, CORGI Consortium, WGS500 Consortium, Germ Cells, Humans, Adenomatous Polyposis Coli, Colorectal Neoplasms, Uveal Neoplasms, Genetic Predisposition to Disease, Endodeoxyribonucleases, Germ-Line Mutation