The Fanconi anemia DNA damage repair pathway in the spotlight for germline predisposition to colorectal cancer

Abstract

Colorectal cancer (CRC) is one of the most common neoplasms in the world. Fanconi anemia (FA) is a very rare genetic disease causing bone marrow failure, congenital growth abnormalities and cancer predisposition. The comprehensive FA DNA damage repair pathway requires the collaboration of 53 proteins and it is necessary to restore genome integrity by efficiently repairing damaged DNA. A link between FA genes in breast and ovarian cancer germline predisposition has been previously suggested. We selected 74 CRC patients from 40 unrelated Spanish families with strong CRC aggregation compatible with an autosomal dominant pattern of inheritance and without mutations in known hereditary CRC genes and performed germline DNA whole-exome sequencing with the aim of finding new candidate germline predisposition variants. After sequencing and data analysis, variant prioritization selected only those very rare alterations, producing a putative loss of function and located in genes with a role compatible with cancer. We detected an enrichment for variants in FA DNA damage repair pathway genes in our familial CRC cohort as 6 families carried heterozygous, rare, potentially pathogenic variants located in BRCA2/FANCD1, BRIP1/FANCJ, FANCC, FANCE and REV3L/POLZ. In conclusion, the FA DNA damage repair pathway may play an important role in the inherited predisposition to CRC.

Figure 1

The Fanconi anemia (FA) DNA damage repair pathway. Genes linked to colorectal cancer (CRC) predisposition by the present report and previous evidence are shaded in gray (adapted from KEGG database, http://www.genome.jp/kegg/pathway.html).

Figure 2

Pedigrees from families FAM3, FAMN4, FAM6, FAM20, FAM40 and H463 are shown. Filled symbol indicate affected for CRC (upper right quarter) adenoma/s (lower right quarter), stomach cancer (lower left quarter) and breast cancer (upper left quarter). Colon, breast, stomach, lung, prostate, kidney, uterine, leukemia and bladder refer to the type of cancer. AA/non-AA, advanced adenoma/nonadvanced adenoma; +, variant carrier. Index cases are indicated with an arrow.