Do the distribution patterns of polymorphisms at the thiopurine S-methyltransferase locus in sub-Saharan populations need revision? Hints from Cabinda and Mozambique.
Genetic data on the thiopurine S-methyltransferase (TPMT) polymorphism were obtained in population samples from Cabinda and Mozambique (located in the western and eastern coasts of sub-Saharan Africa, respectively). The overall frequency of TPMT-deficient alleles was 5.6% in Mozambique and 6.3% in Cabinda. Accordingly, one out of the 103 individuals from Cabinda tested had a genotype associated with TPMT deficiency, yielding a frequency that is threefold higher than heretofore reported in any population. In addition, in both Cabinda or Mozambique, TPMT*8 accounted for a significant proportion of non-functional alleles (nearly 40% in Cabinda). Since the substitution defining TPMT*8 seems to be highly specific of sub-Saharan Africa populations and given the fact it has not been integrated into the set of single nucleotide polymorphisms routinely tested for TPMT, a re-design of molecular screenings should be considered in the future in order to avoid serious underestimates of TPMT deficiency when the enzymatic profiles in populations are unknown.
Oliveira
E
E
Institute of Pathology and Molecular Immunology of University of Porto, Porto, Portugal. eoliveira@ipatimup.pt
Quental
S
S
Alves
S
S
Amorim
A
A
Prata
M J
MJ
D044383:Black People; D015023:Democratic Republic of the Congo; D005787:Gene Frequency; D014644:Genetic Variation; D005838:Genotype; D006801:Humans; D008780:Methyltransferases / Q000172:deficiency / Q000235:genetics*; D009073:Mozambique; D020641:Polymorphism, Single Nucleotide
D008780:Methyltransferases; C022745:thiopurine methyltransferase