Familial colorectal cancer

Colorectal cancer is a heterogeneous disease that is common in both men and women. In addition to lifestyle and environmental risk factors, gene defects can contribute to an inherited predisposition to CRC. CRC is caused by changes in different molecular pathogenic pathways, such as chromosomal instability, CpG island methylator phenotype, and microsatellite instability. Chromosome instability is the most common alteration and is present in almost 85% of all cases (review by Schweiger et al., 2013). Genetic Heterogeneity of Colorectal Cancer Mutations in a single gene result in a marked predisposition to colorectal cancer in 2 distinct syndromes: familial adenomatous polyposis (FAP; 175100) and hereditary nonpolyposis colorectal cancer (HNPCC; see 120435). FAP is caused by mutations in the APC gene (611731), whereas HNPCC is caused by mutations in several genes, including MSH2 (609309), MLH1 (120436), PMS1 (600258), PMS2 (600259), MSH6 (600678), TGFBR2 (190182), and MLH3 (604395). Epigenetic silencing of MSH2 results in a form of HNPCC (see HNPCC8, 613244). Other colorectal cancer syndromes include autosomal recessive adenomatous polyposis (608456), which is caused by mutations in the MUTYH gene (604933), and oligodontia-colorectal cancer syndrome (608615), which is caused by mutations in the AXIN2 gene (604025). The CHEK2 gene (604373) has been implicated in susceptibility to colorectal cancer in Finnish patients. A germline mutation in the PLA2G2A gene (172411) was identified in a patient with colorectal cancer. Germline susceptibility loci for colorectal cancer have also been identified. CRCS1 (608812) is conferred by mutation in the GALNT12 gene (610290) on chromosome 9q22; CRCS2 (611469) maps to chromosome 8q24; CRCS3 (612229) is conferred by variation in the SMAD7 gene (602932) on chromosome 18; CRCS4 (601228) is conferred by variation on 15q that causes increased and ectopic expression of the GREM1 gene (603054); CRCS5 (612230) maps to chromosome 10p14; CRCS6 (612231) maps to chromosome 8q23; CRCS7 (612232) maps to chromosome 11q23; CRCS8 (612589) maps to chromosome 14q22; CRCS9 (612590) maps to 16q22; CRCS10 (612591) is conferred by mutation in the POLD1 gene (174761) on chromosome 19q13; CRCS11 (612592) maps to chromosome 20p12; and CRCS12 (615083) is conferred by mutation in the POLE gene (174762) on chromosome 12q24. Somatic mutations in many different genes, including KRAS (190070), PIK3CA (171834), BRAF (164757), CTNNB1 (116806), FGFR3 (134934), AXIN2 (604025), AKT1 (164730), MCC (159350), MYH11 (160745), PARK2 (602544), RNF43 (612482), and BUB1 (601452) have been identified in colorectal cancer.

OMIM