Genetic predisposition to colorectal cancer: new pieces in the pediatric puzzle.

Colorectal cancer is rare in childhood. The 2 best characterized familial syndromes, hereditary nonpolyposis colorectal cancer (HNPCC, Lynch syndrome) and familial adenomatous polyposis (FAP), are autosomal dominant inherited disorders. HNPCC is relevant to pediatric gastroenterology practice because children and adolescents with underlying colorectal cancer can have germ-line mutations of mismatch repair genes. Recent attention has focused on characterizing genetic predisposition to attenuated FAP in individuals who do not have germ-line mutations in the APC gene. The identification of a second mechanistic explanation called MYH-associated polyposis (MAP), which is an autosomal-recessive condition, has important implications for both screening and management strategies. Hereditary colorectal cancer including HNPCC, FAP, attenuated FAP and MYH-associated polyposis in children are the subject of this review.