title: Quantitative neonatal glucose-6-phosphate dehydrogenase screening: distribution, reference values, and classification by phenotype.
abstract: OBJECTIVE
  To determine enzyme assay reference values for newborns in a Sephardic Jewish population at high risk for glucose-6-phosphate dehydrogenase (G6PD) deficiency.
  
  
  METHODS
  Quantitative G6PD testing was performed on umbilical cord blood. The reduction of nicotinamide adenine dinucleotide phosphate to nicotinamide adenine dinucleotide phosphate-oxidase, reflecting G6PD activity, was measured spectrophotometrically. Hemoglobin (Hb) was measured on the same sample. G6PD activity was recorded as U/g Hb.
  
  
  RESULTS
  Males (N = 1502) were separated into 2 distinct groups: those <7 U/g Hb (n = 243 [16.2%], median 0.28 U/g Hb), designated G6PD deficient, presumably hemizygotes; and those ≥ 9 U/g Hb (n = 1256 [83.8%], 18.76 U/g Hb), designated G6PD normal, presumably hemizygotes. Female (n = 1298) values were a continuum and were categorized based on the male distribution: those <7 U/g Hb (n = 81 [6.2%], 4.84 U/g Hb), G6PD deficient, probably homozogytes; those ≥ 9.5 U/g Hb, equivalent to 50% of the male normal value, (n = 1153 (88.8%), 18.36 U/g Hb), G6PD normal, probably homozygotes; and those with intermediate values (n = 64 [4.9%], 8.61 U/g Hb), probable heterozygotes.
  
  
  CONCLUSIONS
  Accurate identification of the male G6PD-deficient state was possible despite high normal neonatal G6PD values. Female values were presented as a continuum preventing accurate classification but were classified based on male phenotype for practical use.
authors.affiliation: Department of Neonatology, Shaare Zedek Medical Center, Jerusalem, Israel.
authors.forename: Nurit
authors.initials: N
authors.lastname: Algur
authors.forename: Irit
authors.initials: I
authors.lastname: Avraham
authors.forename: Cathy
authors.initials: C
authors.lastname: Hammerman
authors.forename: Michael
authors.initials: M
authors.lastname: Kaplan
mesh_terms: D005260:Female; D005838:Genotype; D005954:Glucosephosphate Dehydrogenase / Q000097:blood*; D005955:Glucosephosphate Dehydrogenase Deficiency / Q000145:classification / Q000175:diagnosis*; D006801:Humans; D007231:Infant, Newborn; D008297:Male; D015997:Neonatal Screening; D010641:Phenotype; D012016:Reference Values
chemical_list: D005954:Glucosephosphate Dehydrogenase