SCREENING SOUTH-AFRICAN FAMILIAL ADENOMATOUS POLYPOSIS FAMILIES FOR THE 5-NUCLEOTIDE DELETION AT CODON-1309 OF THE APC GENE

We report the occurrence of a common five-nucleotide deletion at codon 1309 of the adenomatous polyposis coli (APC) gene in four different S outh African population groups. The mutation causes familial adenomato us polyposis (FAP) in 18% (4/22 unrelated patients screened) of affect ed South Africans, which is similar to the frequency described in seve ral other populations. Knowledge of the gene mutation underlying FAP e nabled conclusive genetic testing of at-risk family members of four in dex patients in which this specific mutation has been characterized. T he non-radioactive heteroduplex method described in this study allowed cost-effective molecular diagnosis directly after electrophoresis of enzymatically-amplified DNA in agarose gels. The resulting reduction o f uncertainty for at-risk relatives is an important benefit of diagnos is at the DNA level.