title: Analysis of gene mutations involved in chloroquine resistance in Plasmodium falciparum parasites isolated from patients in the southwest of Saudi Arabia.
abstract: OBJECTIVE
  Chloroquine has been the drug of choice for the treatment of malaria for many decades. We aimed to examine the molecular basis of chloroquine resistance among Plasmodium falciparum isolates from the southwestern region of Saudi Arabia by analyzing the K76T and N86Y mutations in the PfCRT and PfMDR1 genes, respectively.
  
  
  METHODS
  P falciparum-infected blood spot samples (n=121) were collected on filter papers. DNA was extracted and fragments from the above genes were amplified using nested PCR. The amplicons were digested by ApoI enzyme and sequenced.
  
  
  RESULTS
  Of the 121 samples, 95 and 112 samples could be amplified for PfCRT K76T and PfMDR1 N86Y mutations, respectively. All of the samples amplified for the PfCRT K76T mutation were undigestible by ApoI, suggesting the presence of the K76T mutation. For the PfMDR1 N86Y mutation, 65/109 samples (59.6%) were digestible when treated with ApoI in a pattern, suggestive of the presence of the investigated wild allele (N86). However, 44/109 samples (40.4%) were digestible by ApoI, suggesting the presence of the mutated allele (Y) at position 86. DNA sequencing confirmed these results.
  
  
  CONCLUSIONS
  Surprisingly, all isolates exhibited the mutated allele at codon 76 (K76T) of PfCRT. However, the mutated mutant allele at codon 86 (N86Y) of PfMDR1 was found in 40.4% of the samples studied. To our knowledge, this is the first study that has investigated the existence of the mutation in the PfMDR1 gene in the country. This study will contribute to the development of new strategies for therapeutic intervention against malaria in Saudi Arabia.
authors.affiliation: Biological and Medical Research, King Faisal Specialist Hospital and Research Centre, Riyadh, Saudi Arabia.
authors.forename: Saad M
authors.initials: SM
authors.lastname: Bin Dajem
authors.forename: Ahmed
authors.initials: A
authors.lastname: Al-Qahtani
mesh_terms: D000818:Animals; D000962:Antimalarials / Q000494:pharmacology / Q000627:therapeutic use*; D002738:Chloroquine / Q000494:pharmacology / Q000627:therapeutic use*; D018432:Drug Resistance, Multiple / Q000187:drug effects*; D005784:Gene Amplification; D014644:Genetic Variation; D006801:Humans; D016778:Malaria, Falciparum / Q000188:drug therapy* / Q000453:epidemiology; D026901:Membrane Transport Proteins / Q000235:genetics; D027425:ATP-Binding Cassette, Sub-Family C Proteins / Q000235:genetics; D009154:Mutation; D010963:Plasmodium falciparum / Q000187:drug effects / Q000235:genetics* / Q000302:isolation & purification; D015800:Protozoan Proteins / Q000235:genetics; D012529:Saudi Arabia / Q000453:epidemiology
chemical_list: D000962:Antimalarials; D002738:Chloroquine; D026901:Membrane Transport Proteins; D027425:ATP-Binding Cassette, Sub-Family C Proteins; D015800:Protozoan Proteins; C513498:Mdr1 protein, Plasmodium falciparum; C416369:PfCRT protein, Plasmodium falciparum