S-mephenytoin hydroxylation phenotype and CYP2C19 genotype among Ethiopians

Pharmacogenetics. 1996 Dec;6(6):521-6. doi: 10.1097/00008571-199612000-00005.


The polymorphic metabolism of S-mephenytoin and the distribution of two known deleterious mutant CYP2C19 alleles was determined among 114 healthy unrelated black Ethiopians. Six subjects (5.2%) were poor metabolizers (PMs) of S-mephenytoin. The frequencies of the defective CYP2C19*2 (CYP2C19m1) and CYP2C19*3 (CYP2C19m2) alleles were 0.14 and 0.02, respectively. Three of the PMs were homozygous for the CYP2C19*2 allele and the remaining three PMs were heterozygous for both the CYP2C19*2 and CYP2C19*3 mutant alleles. It is concluded that the frequency of PMs for S-mephenytoin is similar in Ethiopians, Zimbabweans and Caucasians and that the CYP2C19*3 allele, for the first time identified in a black population, together with the CYP2C19*2 allele account for all of the defective CYP2C19 alleles among the Ethiopian PMs.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Alleles
  • Aryl Hydrocarbon Hydroxylases*
  • Cytochrome P-450 CYP2C19
  • Cytochrome P-450 Enzyme System / genetics*
  • Cytochrome P-450 Enzyme System / metabolism
  • Ethiopia
  • Female
  • Gene Frequency
  • Genotype
  • Humans
  • Male
  • Mephenytoin / metabolism*
  • Mixed Function Oxygenases / genetics*
  • Mixed Function Oxygenases / metabolism
  • Phenotype
  • Polymorphism, Genetic*


  • Cytochrome P-450 Enzyme System
  • Mixed Function Oxygenases
  • Aryl Hydrocarbon Hydroxylases
  • CYP2C19 protein, human
  • Cytochrome P-450 CYP2C19
  • Mephenytoin