Polymorphism of debrisoquine 4-hydroxylation and family studies of poor metabolizers in Chinese population.

Debrisoquine hydroxylation capacity determined as the ratio of debrisoquine over 4-OH-debrisoquine in 8-h urine after a single dose (10 mg) was studied in 140 unrelated Chinese Han subjects and 2 families of poor metabolizers (PM) of debrisoquine. In the 140 Chinese subjects the frequency of PM was found to be 1.43% (2/140), much lower than the 5-10% in white population reported. No sex difference was shown on the hydroxylation of debrisoquine. The recoveries of debrisoquin, 4-OH-debrisoquine in 8-h urine were 16 +/- 11 and 13 +/- 6%, respectively. None of the parents in the 2 families was PMs. Phenotype distribution in each family and population was consistent with the hypothesis that debrisoquine 4-OH-hydroxylation activity is under diallelic, monogenetic control, with the PM phenotype inheriting in an autosomal recessive trait.