• to define the inheritance patterns of Familial Adenomatous Polyposis, FAP, and Hereditary non-polyposis colon cancer, HNPCC (Lynch syndrome)

Autosomal dominant inheritance pattern = FAP & HNPCC

Autosomal dominance occurs in every generation, it effects non sex-linked chromosomes and only one chromosome has to be affected

• to differentiate between genetic tests for FAP and HNPCC

Direct sequencing should be conducted for FAP

direct sequencing is when a normal unmutated part of a specific area is compared with another copy of the same area which is suspected to have been mutated, the bases are scaled against eachother and if a base is out of line with the ‘normal’ code the mutatiomn is investigated

HNPCC should undergo microsatellite region testing, for the reasons explained below

if a patient has microsatellite instability it suggests that a patient has HNPCC, we can 90% know this to be true as HNPCC is caused by a mutation of onne or more of 4 genes all of which have a role in DNA missmatch correction, eg they would correct a DNA missmatch that occurs.

A DNA missmatch is more likely to occur at a repetative region (which are known as microsatellite regions) and so if a microsatellite region has DNA missmatch it is likely that a patient has HNPCC and should be tested for it.

it can also undergo immunohistochemical protein staining which allows histology slides to be stained to check for specific proteins presence, more is described about it below.