CYP3A5 genotypes and risk of oesophageal cancer in two South African populations.

CYP3A5 is the major cytochrome P450 enzyme in the oesophagus and metabolises many potentially carcinogenic compounds. The frequencies of CYP3A5 allelic variants, CYP3A5*2, *3, *6 and *7 which code for enzymes with severely decreased activities were compared between 241 oesophageal cancer patients and 272 controls in Black and Mixed Ancestry South Africans. A significantly higher frequency of CYP3A5*3 was observed in the controls compared to patients amongst the Mixed Ancestry group (P=0.025). Individuals homozygous for defective CYP3A5 had reduced risk of developing oesophageal cancer (P=0.032).