Distribution of red cell G6PD and 6PGD phenotypes in Saudi Arabia.

A total of 1112 randomly selected Saudi Arabs, of both sexes living in Jeddah and the surrounding areas, were studied for the distribution of red cell G6PD and 6PGD phenotypes by the methaemoglobin reduction test and starch-gel electrophoresis. The overall G6PD deficiency was 8.4% in males and 7.0% in females. No deficiency of 6PGD was detected. The gene frequencies at the G6PD locus were as follows: in males [GdB+ - 0.86; GdA+ - 0.05; GdB- - 0.06, GdA- - 0.02] and those in females [GdB+ - 0.85; GdA+ - 0.07; GdB- - 0.06; GdA- - 0.01] respectively. The hyperactive allele, GdBKRT originally detected in the Sudan was also present in a low frequency in Saudi Arabs. The frequency of PGDA and PGDC alleles were found to be 0.94 and 0.06 respectively. There was a significant deviation from the Hardey-Weinberg Equilibrium in the distribution of PGDC alleles with an excess of homozygotes (chi 2(1): 54.0) and lack of heterozygotes (chi 2(1): 7.31) probably due to the practice of inbreeding for many generations.