title: Modification to reporting of qualitative fluorescent spot test results improves detection of glucose-6-phosphate dehydrogenase (G6PD)-deficient heterozygote female newborns.
abstract: BACKGROUND
  The glucose-6-phosphate dehydrogenase (G6PD) fluorescent spot test (FST) is a useful screening test for G6PD deficiency, but is unable to detect heterozygote G6PD-deficient females. We sought to identify whether reporting intermediate fluorescence in addition to absent and bright fluorescence on FST would improve identification of mildly deficient female heterozygotes.
  
  
  METHODS
  A total of 1266 cord blood samples (705 male, 561 female) were screened for G6PD deficiency using FST (in-house method) and a quantitative enzyme assay. Fluorescence intensity of the FST was graded as either absent, intermediate or normal. Samples identified as showing absent or intermediate fluorescence on FST were analysed for the presence of G6PD mutations using TaqMan@SNP genotyping assays and direct nucleotide sequencing.
  
  
  RESULTS
  Of the 1266 samples, 87 samples were found to be intermediate or deficient by FST (49 deficient, 38 intermediate). Of the 49 deficient samples, 48 had G6PD enzyme activity of ≤ 9.5 U/g Hb and one sample had normal enzyme activity. All 38 intermediate samples were from females. Of these, 21 had G6PD activity of between 20% and 60%, and 17 samples showed normal G6PD activity. Twenty-seven of the 38 samples were available for mutation analysis of which 13 had normal G6PD activity. Eleven of the 13 samples with normal G6PD activity had identifiable G6PD mutations.
  
  
  CONCLUSIONS
  Glucose-6-phosphate dehydrogenase heterozygote females cannot be identified by FST if fluorescence is reported as absent or present. Distinguishing samples with intermediate fluorescence from absent and bright fluorescence improves detection of heterozygote females with mild G6PD deficiency. Mutational studies confirmed that 85% of intermediate samples with normal enzyme activity had identifiable G6PD mutations.
authors.affiliation: Department of Pathology, Faculty of Medicine, University Malaya, Kuala Lumpur, Malaysia Division of Laboratory Medicine, Department of Pathology, University Malaya Medical Centre, Kuala Lumpur, Malaysia.
authors.forename: V
authors.initials: V
authors.lastname: Nadarajan
authors.forename: H
authors.initials: H
authors.lastname: Shanmugam
authors.forename: P
authors.initials: P
authors.lastname: Sthaneshwar
authors.forename: S
authors.initials: S
authors.lastname: Jayaranee
authors.forename: K S
authors.initials: KS
authors.lastname: Sultan
authors.forename: C
authors.initials: C
authors.lastname: Ang
authors.forename: S
authors.initials: S
authors.lastname: Arumugam
mesh_terms: D000483:Alleles; D004789:Enzyme Activation / Q000235:genetics; D005260:Female; D005954:Glucosephosphate Dehydrogenase / Q000235:genetics* / Q000378:metabolism; D005955:Glucosephosphate Dehydrogenase Deficiency / Q000175:diagnosis* / Q000235:genetics* / Q000378:metabolism; D006579:Heterozygote; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D009154:Mutation / Q000235:genetics; D015997:Neonatal Screening
chemical_list: D005954:Glucosephosphate Dehydrogenase