title: Evaluation of the phenotypic test and genetic analysis in the detection of glucose-6-phosphate dehydrogenase deficiency.
abstract: BACKGROUND
  Glucose-6-phosphate dehydrogenase (G6PD) deficiency is particularly prevalent in historically malaria-endemic countries. Although most individuals with G6PD deficiency are asymptomatic, deficiency can result in acute haemolytic anaemia after exposure to oxidative agents. A reliable test is necessary for diagnosing the deficiency to prevent an acute haemolytic crisis following, for example, anti-malarial treatment. The aim of this study was to investigate which method was the best predictor of this disorder.
  
  
  METHODS
  The present study investigated four G6PD activity detections (fluorescence spot (FS), methaemoglobin reduction (MR), biochemical and cytochemical test). These methods accompanied with mutation analysis of blood samples were taken from 295 apparently healthy individuals with unknown G6PD deficiency status.
  
  
  RESULTS
  Molecular characterization of 295 Thai adults revealed an overall prevalence of 14.2%. The G6PD Viangchan (871 G>A) was the most common (83.3%), followed by G6PD Mahidol (487G>A) (11.9%), and G6PD Union (1360 C>T) (4.8%). There were two cases of G6PD deficiency carrying the double mutations of Viangchan (871G > A)-Mahidol (487G > A) and Viangchan (871G > A)-Union (1360C > T). In comparison, the prevalence of G6PD deficiency was 6.1% by FS test and 7.1% by MR test. G6PD activity was 11 ± 2.5 IU/gHb in non-deficient females (mean ± SD), and 10.9 ± 0.6 IU/gHb in non-deficient males. The upper and lower limit cut-off points for partial and severe deficiency in adults were 5.7 IU/gHb (60% of the normal mean) and 0.95 IU/gHb (10% of the normal mean), respectively. All hemizygote, homozygote and double mutations were associated with severe enzyme deficiency (the residual enzyme activity <10% of the normal mean), whereas only 14.3% of the heterozygote mutations showed severe enzyme deficiency. Based on the cut-off value <5.7 IU/gHb, the quantitative G6PD assay diagnosed 83% of cases as G6PD-deficient. Using a cut-off number of negative cell >20% in the cytochemical assay to define G6PD deficiency, the prevalence of G6PD deficiency was closest to the molecular analysis (12.9% G6PD-deficient) compared to the others methods.
  
  
  CONCLUSIONS
  The cytochemical method is a significant predictor of this disease, while FS and MR test are recommended for the detection of severe G6PD deficiency in developing countries.
authors: Department of Molecular Tropical Medicine and Genetics, Faculty of Tropical Medicine, Mahidol University, Bangkok, Thailand.
authors: Duangdao
authors: D
authors: Nantakomol
authors: Rick
authors: R
authors: Paul
authors: Attakorn
authors: A
authors: Palasuwan
authors: Nicholas P J
authors: NP
authors: Day
authors: Nicholas J
authors: NJ
authors: White
authors: Mallika
authors: M
authors: Imwong
mesh_terms: D000293:Adolescent; D000328:Adult; D019411:Clinical Laboratory Techniques / Q000379:methods*; D005260:Female; D005954:Glucosephosphate Dehydrogenase / Q000032:analysis* / Q000235:genetics*; D005955:Glucosephosphate Dehydrogenase Deficiency / Q000175:diagnosis*; D006651:Histocytochemistry / Q000379:methods*; D006801:Humans; D008297:Male; D008875:Middle Aged; D055815:Young Adult
chemical_list: D005954:Glucosephosphate Dehydrogenase
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