Volume 68, Issue 2
  • ISSN: 0002-9637
  • E-ISSN: 1476-1645


The mutation leading to the substitution of a threonine (T76) for a lysine at position 76 of the chloroquine resistance transporter (PfCRT) was genotyped in 100 Nigerian children with asymptomatic parasitemia. Isolates containing both variants were found to harbor higher numbers of parasite clones ( < 0.002). The prevalence of the T76 variant decreased with age ( < 0.0001) and increased with blood levels of chloroquine (CQ) ( < 0.0001). Whereas the K76 allele was more frequent in individuals without detectable plasma CQ levels (79.7%), only the T76 variant was observed in children with CQ levels > 150 nmol/L. In individuals without detectable plasma CQ, the proportion of those with T76 decreased from 60% in children < 2 years old to 23.5% in children ≥ 6 years old ( < 0.01). The association of actual blood levels of CQ and the occurrence of T76 underlines that the T76 variant is in fact the mediator of CQ resistance.


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  • Received : 14 Jan 2002
  • Accepted : 11 Sep 2002

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