Following genetic counselling in a family for Familial polyposis coli (FPC) next screening test is

Ans. is 'd' i.e. APC gene Schwartz writes - "Flexible sigmoidoscopy of first-degree relatives of FAP (Familial adenomatous polyposis) patients beginning at age 10 to 15 years has been the traditional mainstay of screening. Today following genetic counselling, APC gene testing may be used to screen family members providing an APC mutation has been identified in a family member."Familial adenomatous polyposis (FAP) is a dominantly inherited colon cancer syndrome due to germline mutations in the adenomatous polyposis coli (APC) tumor suppressor gene on chromosome 5.Patients with this syndrome develop hundreds to thousands of adenomas in the colon which if left untreated will eventually develop into colon cancer.Each of the FAP adenomas has lost the normal remaining allele of APC gene but has not yet accumulated the required additional mutations to generate fully malignant cells. In due course of time many of these adenomas acquire further genetic abnormalities and develop into fully malignant cancers. APC gene is thus considered to be a gatekeeper for colon tumorigenesis.The detection of APC gene mutation in family members of a FAP patient helps in making a definitive diagnosis before the development of polyps.So APC gene testing is used to screen family members