Quantitative Glucose-6-phosphate Dehydrogenase Research Articles

Tafenoquine and G6PD: a primer for clinicians.

Tafenoquine, an 8-aminoquinoline, is now indicated for causal prophylaxis against all human malarias and as radical curative (anti-relapse) treatment against Plasmodium vivax and Plasmodium ovale. As with other 8-aminoquinolines, tafenoquine causes hemolysis in individuals with glucose-6-phosphate dehydrogenase (G6PD) deficiency (hemizygous males and homozygous females) and is contraindicated in this population. Those with intermediate G6PD activity (heterozygous females) are also at risk for hemolysis. Awareness of how to prescribe tafenoquine in relation to G6PD status is needed so it can be used safely. A standard literature search was performed on varying combinations of the terms tafenoquine, Arakoda, Kodatef, Krintafel, Kozenis, primaquine, G6PD deficiency, malaria prophylaxis and radical cure. The data were gathered and interpreted to review how tafenoquine should be prescribed in consideration of the G6PD status of an individual and traveller. Tafenoquine should only be given to those with G6PD activity >70% of the local population median. Qualitative G6PD tests are sufficient for diagnosing G6PD deficiency in males. However, in females quantitative G6PD testing is necessary to differentiate deficient, intermediate and normal G6PD statuses. Testing for G6PD deficiency is mandatory before tafenoquine prescription. Measures can be taken to avoid tafenoquine administration to ineligible individuals (i.e. due to G6PD status, age, pregnancy and lactation). Primaquine is still necessary for some of these cases. This review provides actions that can be taken to diagnose and manage hemolysis when tafenoquine is given inadvertently to ineligible individuals. Attention to G6PD status is required for safe prescription of tafenoquine. A high index of suspicion is needed if hemolysis occurs. Clinicians should seek evidence-based information for the management and treatment of iatrogenicy hemolysis caused by 8-aminoquinolines.

Co-inheritance of glucose-6-phosphate dehydrogenase deficiency mutations and hemoglobin E in a Kachin population in a malaria-endemic region of Southeast Asia

Glucose-6-phosphate dehydrogenase (G6PD) deficiency and hemoglobin E (HbE, β26 Glu-Lys) are two common red cell disorders in Southeast Asia. G6PD deficiency produces hemolytic anemia, which can be triggered by certain drugs or infections. HbE is asymptomatic or is manifested as microcytic, minimally hemolytic anemia. The association between G6PD deficiency and HbE is little understood. This study aimed to investigate G6PD deficiency and HbE in a Kachin ethnic group in the China-Myanmar border area. G6PD enzyme activity was measured using a quantitative G6PD assay, G6PD variants genotyped by the SNaPshot assay, and an HbE gene mutation identified by an amplification refractory mutation system and subsequently confirmed by using a reverse dot blot hybridization assay from 100 unrelated individuals in the study area. G6PD enzyme activity ranged from 0.4 to 24.7 U/g Hb, and six males had severe G6PD deficiency (<0.12–1.2 U/g Hb), while six males and 12 females had mild G6PD deficiency (>1.2–4.5 U/g Hb). Among the 24 G6PD-deficient subjects, 22 (92%) had the Mahidol 487G>A mutation (12 male hemizygotes, one female homozygote, and nine female heterozygotes), while the G6PD genotypes in two female subjects were unknown. HbE was identified in 39 subjects (20 males and 19 females), including 15 HbEE (seven males and eight females) and 24 HbAE (13 males and 11 females). Twenty-three subjects co-inherited both G6PD deficiency and HbE (22 with HbAE and one with HbEE). Whereas mean Hb levels were not significantly different between the HbA and HbE groups, G6PD-deficient males had significantly lower Hb levels than G6PD-normal males (P < 0.05, t-test). However, it is noteworthy that two G6PD-deficient hemizygous males with HbAE were severely anemic with Hb levels below 50 g/L. This study revealed high prevalence of co-inheritance of G6PD deficiency with HbAE in the Kachin ethnicity, and a potential interaction of the G6PD Mahidol 487G>A and HbAE in males leading to severe anemia. The presence of 6% males with severe G6PD deficiency raised a major concern in the use of primaquine for radical cure of vivax malaria.

Glucose-6-phosphate dehydrogenase deficiency prevalence and genetic variants in malaria endemic areas of Colombia

BackgroundGlucose 6-phosphate dehydrogenase (G6PD) is an enzyme involved in prevention of cellular oxidative damage, particularly protecting erythrocytes from haemolysis. An estimated 400 million people present variable degrees of inherited G6PD deficiency (G6PDd) which puts them at risk for developing haemolysis triggered by several risk factors including multiple drugs and certain foods. Primaquine (PQ) is a widely used anti-malarial drug that can trigger haemolysis in individuals with G6PDd. Intensification of malaria control programmes worldwide and particularly malaria elimination planning in some regions recommend a more extensive use of PQ and related drugs in populations with different G6PDd prevalence. This a preliminary study to assess the prevalence of G6PDd in representative malaria endemic areas of Colombia by measuring G6PD phonotype and genotypes.MethodsVolunteers (n = 426) from four malaria endemic areas in Colombia (Buenaventura, Tumaco, Tierralta and Quibdo) were enrolled. Blood samples were drawn to evaluate G6PD enzymatic activity by using a quantitative G6PD test and a subset of samples was analysed by PCR–RFLP to determine the frequency of the three most common G6PD genotypic variants: A−, A+ and Mediterranean.ResultsA total of 28 individuals (6.56 %) displayed either severe or intermediate G6PDd. The highest prevalence (3.51 %) was in Buenaventura, whereas G6PDd prevalence was lower (<1 %) in Tierralta and Quibdo. G6PD A alleles were the most frequent (15.23 %) particularly in Buenaventura and Tumaco. Overall, a high frequency of G6PD A− genotype, followed by A+ genotype was found in the analysed population.ConclusionsG6PDd based on enzymatic activity as well as G6PD A allelic variants were found in malaria-endemic populations on the Pacific coast of Colombia, where most of malaria cases are caused by Plasmodium vivax infections. These infections are treated for 14 days with PQ, however there are no official reports of PQ-induced haemolytic crises. Further assessment of G6PDd prevalence in malaria endemic areas in Colombia is crucial in view of possible mass drug administration for malaria elimination in these regions, as well as implementation of appropriate G6PDd diagnostic methods.

Real-time monitoring of glucose-6-phosphate dehydrogenase activity using liquid droplet arrays and its application to human plasma samples

Glucose-6-phosphate dehydrogenase (G6PD) regulates nicotinamide adenine dinucleotide phosphate (NADPH) levels and is related to the pathogenesis of various diseases, including G6PD deficiency, type 2 diabetes, aldosterone-induced endothelial dysfunction, and cancer. Therefore, a highly sensitive array-based assay for determining quantitative G6PD activity is required. Here, we developed an on-chip G6PD activity assay using liquid droplet fluorescence arrays. Quantitative G6PD activity was determined by calculating reduced resorufin concentrations in liquid droplets. The limit of detection (LOD) of this assay was 0.162mU/ml (2.89pM), which is much more sensitive than previous assays. We used our activity assay to determine kinetic parameters, including Michaelis–Menten constants (Km) and maximum rates of enzymatic reaction (Vmax) for NADP+ and G6P, and half-maximal inhibitory concentrations (IC50). We successfully applied this new assay to determine G6PD activity in human plasma from normal healthy individuals (n=30) and patients with inflammation (n=30). The inflammatory group showed much higher G6PD activities than did the normal group (p<0.001), with a high area under the curve value of 0.939. Therefore, this new activity assay has the potential to be used for diagnosis of G6PD-associated diseases and utilizing kinetic studies.

Point-of-Care Quantitative Measure of Glucose-6-Phosphate Dehydrogenase Enzyme Deficiency.

Widespread newborn screening on a point-of-care basis could prevent bilirubin neurotoxicity in newborns with glucose-6-phosphate dehydrogenase (G6PD) deficiency. We evaluated a quantitative G6PD assay on a digital microfluidic platform by comparing its performance with standard clinical methods. G6PD activity was measured quantitatively by using digital microfluidic fluorescence and the gold standard fluorescence biochemical test on a convenience sample of 98 discarded blood samples. Twenty-four samples were designated as G6PD deficient. Mean ± SD G6PD activity for normal samples using the digital microfluidic method and the standard method, respectively, was 9.7 ± 2.8 and 11.1 ± 3.0 U/g hemoglobin (Hb), respectively; for G6PD-deficient samples, it was 0.8 ± 0.7 and 1.4 ± 0.9 U/g Hb. Bland-Altman analysis determined a mean difference of -0.96 ± 1.8 U/g Hb between the digital microfluidic fluorescence results and the standard biochemical test results. The lower and upper limits for the digital microfluidic platform were 4.5 to 19.5 U/g Hb for normal samples and 0.2 to 3.7 U/g Hb for G6PD-deficient samples. The lower and upper limits for the Stanford method were 5.5 to 20.7 U/g Hb for normal samples and 0.1 to 2.8 U/g Hb for G6PD-deficient samples. The measured activity discriminated between G6PD-deficient samples and normal samples with no overlap. Pending further validation, a digital microfluidics platform could be an accurate point-of-care screening tool for rapid newborn G6PD screening.

G6PD deficiency at Sumba in Eastern Indonesia is prevalent, diverse and severe: implications for primaquine therapy against relapsing Vivax malaria.

Safe treatment of Plasmodium vivax requires diagnosis of both the infection and status of erythrocytic glucose-6-phosphate dehydrogenase (G6PD) activity because hypnozoitocidal therapy against relapse requires primaquine, which causes a mild to severe acute hemolytic anemia in G6PD deficient patients. Many national malaria control programs recommend primaquine therapy without G6PD screening but with monitoring due to a broad lack of G6PD deficiency screening capacity. The degree of risk in doing so hinges upon the level of residual G6PD activity among the variants present in any given area. We conducted studies on Sumba Island in eastern Indonesia in order to assess the potential threat posed by primaquine therapy without G6PD screening. We sampled 2,033 residents of three separate districts in western Sumba for quantitative G6PD activity and 104 (5.1%) were phenotypically deficient (<4.6U/gHb; median normal 10U/gHb). The villages were in two distinct ecosystems, coastal and inland. A positive correlation occurred between the prevalence of malaria and G6PD deficiency: 5.9% coastal versus inland 0.2% for malaria (P<0.001), and 6.7% and 3.1% for G6PD deficiency (P<0.001) at coastal and inland sites, respectively. The dominant genotypes of G6PD deficiency were Vanua Lava, Viangchan, and Chatham, accounting for 98.5% of the 70 samples genotyped. Subjects expressing the dominant genotypes all had less than 10% of normal enzyme activities and were thus considered severe variants. Blind administration of anti-relapse primaquine therapy at Sumba would likely impose risk of serious harm.

Lower reference limits of quantitative cord glucose-6-phosphate dehydrogenase estimated from healthy term neonates according to the Clinical and Laboratory Standards Institute guidelines: a cross sectional retrospective study.

BackgroundPrevious studies have reported the lower reference limit (LRL) of quantitative cord glucose-6-phosphate dehydrogenase (G6PD), but they have not used approved international statistical methodology. Using common standards is expecting to yield more true findings. Therefore, we aimed to estimate LRL of quantitative G6PD detection in healthy term neonates by using statistical analyses endorsed by the International Federation of Clinical Chemistry (IFCC) and the Clinical and Laboratory Standards Institute (CLSI) for reference interval estimation.MethodsThis cross sectional retrospective study was performed at King Abdulaziz Hospital, Saudi Arabia, between March 2010 and June 2012. The study monitored consecutive neonates born to mothers from one Arab Muslim tribe that was assumed to have a low prevalence of G6PD-deficiency. Neonates that satisfied the following criteria were included: full-term birth (37 weeks); no admission to the special care nursery; no phototherapy treatment; negative direct antiglobulin test; and fathers of female neonates were from the same mothers’ tribe. The G6PD activity (Units/gram Hemoglobin) was measured spectrophotometrically by an automated kit. This study used statistical analyses endorsed by IFCC and CLSI for reference interval estimation. The 2.5th percentiles and the corresponding 95% confidence intervals (CI) were estimated as LRLs, both in presence and absence of outliers.Results207 males and 188 females term neonates who had cord blood quantitative G6PD testing met the inclusion criteria. Method of Horn detected 20 G6PD values as outliers (8 males and 12 females). Distributions of quantitative cord G6PD values exhibited a normal distribution in absence of the outliers only. The Harris-Boyd method and proportion criteria revealed that combined gender LRLs were reliable. The combined bootstrap LRL in presence of the outliers was 10.0 (95% CI: 7.5-10.7) and the combined parametric LRL in absence of the outliers was 11.0 (95% CI: 10.5-11.3).ConclusionThese results contribute to the LRL of quantitative cord G6PD detection in full-term neonates. They are transferable to another laboratory when pre-analytical factors and testing methods are comparable and the IFCC-CLSI requirements of transference are satisfied. We are suggesting using estimated LRL in absence of the outliers as mislabeling G6PD-deficient neonates as normal is intolerable whereas mislabeling G6PD-normal neonates as deficient is tolerable.

Glucose 6 Phosphate Dehydrogenase Deficiency Unmasked by Diabetic Ketoacidosis: An Underrated Phenomenon

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is an X-linked disease responsible for moderate to severe hemolytic anaemia. Despite being the most common erythrocyte enzyme disorder, it is often overlooked in the regular diagnostic parlance. A 40-year-old male patient admitted to the casualty with an acutely exacerbated diabetic ketoacidosis, showed features of hemolytic anaemia on peripheral smear examination. Crucially, the spherocytes and bite cells suggested a possibility of G6PD deficiency. This was substantiated by an increased reticulocyte count (6.8%) and a reduced quantitative G6PD enzyme assay (7.2%). There was no significant family or prior medical/ drug history. Interestingly, the hemolytic features were evidenced when blood glucose levels were returning to normal values. The insulin mediated NADPH loss may have resulted in an increased erythrocyte oxidant sensitivity and a loss of sulfhydryl group availability; causing hemolysis to manifest. G6PD deficiency is conventionally affiliated with drug induced oxidative stress. But an association with a diabetes mellitus is seldom reported. This case is being presented as it highlights the lesser known complication of diabetic crisis such as hemolysis secondary to a G6PD deficiency.

Neonatal Hyperbilirubinemia in infants with G6PD c.563C &gt; T Variant

BackgroundThere is a strong correlation between glucose-6-phosphate dehydrogenase (G6PD) deficiency and neonatal hyperbilirubinemia with a rare but potential threat of devastating acute bilirubin encephalopathy. G6PD deficiency was observed in 4–14% of hospitalized icteric neonates in Pakistan. G6PD c.563C > T is the most frequently reported variant in this population. The present study was aimed at evaluating the time to onset of hyperbilirubinemia and the postnatal bilirubin trajectory in infants having G6PD c.563C > T.MethodsThis was a case–control study conducted at The Aga Khan University, Pakistan during the year 2008. We studied 216 icteric male neonates who were re-admitted for phototherapy during the study period. No selection was exercised. Medical records showed that 32 were G6PD deficient while 184 were G6PD normal. Each infant was studied for birth weight, gestational age, age at the time of presentation, presence of cephalhematoma, sepsis and neurological signs, peak bilirubin level, age at peak bilirubin level, days of hospitalization, whether phototherapy or exchange blood transfusion was initiated, and the outcome. During hospital stay, each baby was tested for complete blood count, reticulocyte count, ABO and Rh blood type, direct antiglobulin test and quantitative G6PD estimation [by kinetic determination of G6PDH]. G6PDgenotype was analyzed in 32 deficient infants through PCR-RFLP analysis and gene sequencing.ResultsG6PD variants c.563C > T and c.131 C > G were observed in 21 (65%) and three (9%) of the 32 G6PD deficient infants, respectively. DNA of eight (25%) newborns remained uncharacterized. In contrast to G6PD normal neonates, infants with c.563C > T variant had significantly lower enzyme activity (mean ± 1SD; 0.3 ± 0.2 U/gHb vs. 14.0 ± 4.5 U/gHb, p < 0.001) experienced higher peak levels of total serum bilirubin (mean ± 1SD; 16.8 ± 5.4 mg/dl vs. 13.8 ± 4.6 mg/dl, p = 0.008) which peaked earlier after birth (mean ± 1SD 2.9 ± 1.6 vs. 4.3 ± 2.3 days, p = 0.007). No statistically significant difference was observed in mean weight, age at presentation, hemoglobin, reticulocyte count, TSH level, hospital stay or in the frequency of initiation of phototherapy or blood exchange between the two groups.ConclusionsWe concluded that infants with G6PD c.563C > T variant developed jaundice earlier than infants with normal G6PD enzyme levels. Compared to G6PD normal infants, G6PD c.563C > T carrying infants had significantly low G6PD activity.

Molecular heterogeneity of glucose-6-phosphate dehydrogenase deficiency in Gaza Strip Palestinians

Glucose-6-phosphate dehydrogenase (G6PD) deficiency, affecting more than 500 million people worldwide, is one of the most common of inherited disorders. There are 186 G6PD mutations published, with mutational clustering within defined ethnic/racial groups. However comprehensive molecular characterization of ethnically associated G6PD mutants and their clinical implications are lacking. Eighty unrelated Palestinian children hospitalized for hemolysis were studied. G6PD activity was determined by quantitative spectrophotometry and G6PD mutations were analyzed by sequencing of gDNA. 65 of 80 children (81%) had G6PD deficiency, accounting for most of the hemolytic disease in this age group. G6PD Mediterranean(c.563T), African G6PD A-(c.202A/c.376G), and G6PD Cairo(c.404C) were common with relative allele frequencies of 0.33 [1], 0.26, and 0.18 respectively. Two other variants were discovered, G6PD Beverly Hills(c.1160A) mutation, and a novel G6PD missense mutation c.536G>A (Ser179Asn), designated G6PD "Gaza". Three samples exhibited enzyme deficiency without detectable exonic or exon/intron boundary mutations. G6PD deficiency accounts for the majority of diagnoses for hemolysis in Palestinian children (81%), providing support for newborn G6PD deficiency screening programs. We report unanticipated molecular heterogeneity of G6PD variants among Gaza Strip Palestinians greater than reported in neighboring Arab populations. We report a high proportion of affected children with G6PD Cairo, which was observed previously in only a single Egyptian, and a novel mutation G6PD "Gaza".

Frequency of glucose‐6‐phosphate dehydrogenase–deficient red blood cell units in a metropolitan transfusion service

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is characterized by red blood cell (RBC) destruction in response to oxidative stress. Although blood donors are not routinely screened for G6PD deficiency, the transfusion of stored G6PD-deficient RBCs may have serious adverse outcomes. By measuring G6PD enzyme activity of RBC units from a large metropolitan hospital transfusion service, we sought to determine 1) the prevalence of G6PD-deficient RBC units, 2) if G6PD activity changes during storage, and 3) if G6PD activity in segments correlates with its activity in the bags. Quantitative G6PD activity was measured in 301 randomly selected RBC units and 73 D+C-E- (i.e., R r or R R ) RBC units, all stored in additive solutions. G6PD deficiency was defined as activity less than 60% of the normal mean. The frequency of G6PD-deficient units in the general inventory was 0.3% (1/301; 95% confidence interval [CI], <0.01%-2.1%). In contrast, its frequency in D+C-E- RBC units was 12.3% (9/73; 95% CI, 6.4%-22.0%). G6PD activity did not significantly change during the 42-day storage period, and G6PD activity measured in RBC storage bags and attached segments correlated well (r=0.7-0.9, p ≤ 0.001, Spearman rank correlation). Although the frequency of G6PD-deficient RBC units in the transfusion service general inventory was relatively low, it was significantly higher among a subset of R r or R R units. The latter are preferentially allocated for transfusion to patients with sickle cell disease to decrease the risk of RBC alloimmunization, possibly allowing more of these units to be inadvertently targeted to these patients.

Performance of the CareStart™ G6PD Deficiency Screening Test, a Point-of-Care Diagnostic for Primaquine Therapy Screening

Development of reliable, easy-to-use, rapid diagnostic tests (RDTs) to detect glucose-6-phosphate dehydrogenase (G6PD) deficiency at point of care is essential to deploying primaquine therapies as part of malaria elimination strategies. We assessed a kit under research and development called CareStart™ G6PD deficiency screening test (Access Bio, New Jersey, USA) by comparing its performance to quantitative G6PD enzyme activity using a standardized spectrophotometric method (‘gold standard’). Blood samples (n = 903) were collected from Cambodian adults living in Pailin province, western Cambodia. G6PD enzyme activities ranged from 0 to 20.5 U/g Hb (median 12.0 U/g Hg). Based on a normal haemoglobin concentration and wild-type G6PD gene, the normal values of G6PD enzymatic activity for this population was 3.6 to 20.5 U/g Hg (95th percentiles from 5.5 to 17.2 U/g Hg). Ninety-seven subjects (10.7%) had <3.6 U/g Hg and were classified as G6PD deficient. Prevalence of deficiency was 15.0% (64/425) among men and 6.9% (33/478) among women. Genotype was analyzed in 66 G6PD-deficient subjects and 63 of these exhibited findings consistent with Viangchang genotype. The sensitivity and specificity of the CareStart™ G6PD deficiency screening test was 0.68 and 1.0, respectively. Its detection threshold was <2.7 U/g Hg, well within the range of moderate and severe enzyme deficiencies. Thirteen subjects (1.4%, 12 males and 1 female) with G6PD enzyme activities <2 U/g Hg were falsely classified as “normal” by RDT. This experimental RDT test here evaluated outside of the laboratory for the first time shows real promise, but safe application of it will require lower rates of falsely “normal” results.

Incidence and Association of 563 C/T Mediterranean and the Silent 1311C/T G6PD Mutations in G6PD-deficient Egyptian Children

Background: Molecular characterization of glucose-6-phosphate dehydrogenase (G6PD) deficiency variants is essential, especially since the biochemical characterization has lost its significance due to the individual variability. As a result, cases can be misdiagnosed. The present study was designed to determine the incidence of G6PD Mediterranean (Med) mutation among Egyptian children with G6PD deficiency as well as its molecular association with the G6PD 1311T silent polymorphism. Methods: Fifty G6PD-deficient children were subjected to quantitative G6PD enzyme assay. A polymerase chain reaction-amplification refractory mutation system (PCR-ARMS) technique was used to detect the G6PD Med mutation, and polymerase chain reactionrestriction fragment length polymorphism (PCRRFLP) was used to assess the associated G6PD 1311T silent polymorphism. Results: G6PD Med was found in 62% and G6PD 1311T polymorphism in 52% of the patients. The association between both mutations was statistically significant. Conclusion: Glucose-6-phosphate dehydrogenase Med mutation is 1 of the most common mutations causing G6PD deficiency among Egyptian children with G6PD deficiency, with linkage disequilibrium between this G6PD mutation and thymine at nucleotide (nt) 1311.

Comparison of a semiquantitative and a quantitative method for neonatal screening of glucose 6-phosphate dehydrogenase deficiency with subsequent confirmation by allelic discrimination assays

Glucose 6-phosphate dehydrogenase (G6PD) deficiency is a X-linked disorder causing neonatal jaundice and haemolysis on oxidative stress. We compared the currently used fluorescent spot test (FST) against a quantitative assay (OSMMR2000-D) and molecular testing methods for screening and identification of G6PD deficient neonates. A total of 1371 cord blood samples were tested using the semiquantitative FST and quantitative G6PD assay. Positive FST samples were subjected to allelic discrimination assays for G6PD Viangchan, Mediterranean, Canton and Kaiping, which encompass over 75% of the G6PD mutations detected in our population. Positive FST results were seen in 86 (6.3%) of the samples tested. Mean G6PD level using the quantitative assay was 15.3 U/g haemoglobin (Hgb) with 60% and 20% enzyme activity 9.2 and 3.1 U/g Hgb, respectively. Twenty-one of the 86 samples detected as positive by FST had activity above 9.2 U/g Hgb, 10 of which were identified as harbouring one of the four mutations tested. The quantitative assay used in this study, using cord blood samples may cause false negative results if limits are established as proposed. We propose that the FST remains an effective screening tool for G6PD deficiency and can be supplemented by rapid real time molecular identification methods for confirmation.

An update on the prevalence of glucose-6-phosphate dehydrogenase deficiency and neonatal jaundice in Tehran neonates

Objectives: The aim of this study was to screen newborns in Tehran for glucose-6-phosphate dehydrogenase (G6PD) deficiency in relation to hyperbilirubinemia and jaundice. Design and methods: We performed quantitative and qualitative red blood cell (RBC) G6PD assays in cord blood of 2000 male and female at-term neonates. Observations for jaundice and bilirubin determination were made in G6PD-deficient and normal groups. Those with severe jaundice were treated with phototherapy or exchange transfusion. Results: Our results showed that 2.1% (3.6% of males and 0.6% of females) was G6PD-deficient. Those with severe jaundice and hyperbilirubinemia (160 normal and 17 G6PD-deficient) were hospitalized and treated with phototherapy or exchange transfusion. Bilirubin levels in G6PD-deficient neonates were somewhat higher compared to G6PD-normal babies (18.8 ± 2.4 mg/dl [321.5 ± 41 μmol/l] vs. 15.7 ± 3.2 mg/dl [268.5 ± 54.7 μmol/l]; P < 0.05). G6PD activity was significantly lower in G6PD-deficient group than in the normal group (2.1 ± 0.7 vs. 12.5 ± 5.0 U/g Hb; P < 0.001). Conclusion: This study shows that the incidence of G6PD deficiency in newborns of Tehran is 2.1%, which is relatively high, and also hyperbilirubinemia and jaundice are approximately 3-fold higher in G6PD-deficients than in the G6PD-normal group (51% vs. 16%). This emphasizes the necessity of neonatal screening on cord blood samples of both sexes for G6PD deficiency and the need to watch closely for development of hyperbilirubinemia.

Glucose-6-phosphate dehydrogenase (G6PD) mutations in Thailand: G6PD Viangchan (871G>A) is the most common deficiency variant in the Thai population.

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is the most common hereditary disorder in humans. Through a population study for G6PD deficiency using a cord blood quantitative G6PD assay in Bangkok, Thailand, we found that the prevalence of G6PD deficiency is 11.1% in Thai male (N=350) and 5.8% in female (N=172) cord blood samples. Among the neonates with hyperbilirubinemia, the prevalence of G6PD deficiency is 22.1% in males (N=140) and 10.1% in females (N=89). We developed a PCR-restriction enzyme-based method to identify G6PD Viangchan (871G>A), and searched for this and 9 other mutations in DNA from G6PD deficient blood samples. G6PD Viangchan (871G>A) was the most common mutation identified (54%), followed by G6PD Canton (1376G>T; 10%), G6PD Mahidol (487G>A; 8%), G6PD Kaiping (1388G>A; 5%), G6PD Union (1360C>T; 2.6%) and "Chinese-5" (1024C>T; 2.6%). Among 20 neonates with hyperbilirubinemia, G6PD Viangchan was also most frequently identified (60%), followed by G6PD Canton (10%), G6PD Mahidol, G6PD Union, and G6PD Kaiping (5% each). G6PD Viangchan appears from this study to be the most common G6PD mutation in the Thai population, bringing into question previous reports that G6PD Mahidol is most prevalent. G6PD Viangchan, together with G6PD Mahidol and G6PD Canton, are responsible for over 70% of G6PD deficiency in this study of Thais. With the data from other Southeast Asian ethnic groups such as Laotians, G6PD Viangchan (871G>A) is probably the most common variant in non-Chinese Southeast Asian population.

Glucose-6-phosphate dehydrogenase deficiency neonatal screening: preliminary evidence that a high percentage of partially deficient female neonates are missed during routine screening

To provide preliminary evidence that the currently employed semiquantitative method of screening for glucose-6-phosphate dehydrogenase (G6PD) deficiency can only detect infants who are totally deficient for G6PD and misses all cases of partial G6PD deficiency. General population: 2150 randomly selected blood samples from the Blood Donation Department, Speliopouleion General Hospital, Athens, Greece. Neonate population: 2000 samples from neonates (50% male; 50% female) in maternity hospitals in the greater Athens area. High risk population: a total of 545 individuals from 133 families in the Athens area, the minimum acceptance criteria being the parents and any brother or sister. Blood specimens from neonates or adults were collected and either spotted and dried on special filter paper (Schleicher and Schull 2992, Darmstadt, Germany) or used in tubes after being heparinised. For the quantitative evaluation of G6PD enzyme activity, the Quantase G6PD screening kit (Quantase Limited, Perth, UK) was used. Quantase G6PD controls (Quantase Limited) were used at three levels of G6PD. These controls are rated at 24, 30, and 37 degrees C. Alternatively, we used the Sigma G6PDH controls (Sigma Chemical Company, St Louis, USA) which are rated at 30 and 37 degrees C. The assay was performed according to the instructions included in the kit with the modification for haemoglobin normalisation. General population: 36 females who were classified as having normal enzymatic activity with the semiquantitative test, were classified as partially deficient with the quantitative test. Neonate population: using the quantitative test, the percentage of G6PD deficient neonates in this population was 5.5%, compared with 3.17% reported in routine screening using the semiquantitative method. High risk population: the quantitative method detected 28 cases of total or partial G6PD deficiency in sisters of males with known total deficiency. The semiquantitative A considerable amount of partially G6PD deficient female neonates (heterozygotes) are undetected and classified as having normal enzymatic activity using the semiquantitative method, which uses a cut off of 2.1 U/g haemoglobin (Hb). The use of a fully quantitative G6PD screening kit is proposed, employing the automated haemoglobin normalisation and a cut off of 6.4 U/g Hb. Any neonate with an activity below this mark should be regarded as G6PD deficient, and all preventive measures should be taken.

Screening for glucose-6-phosphate dehydrogenase deficiency prior to dapsone therapy

Dapsone is widely used in dermatological practice. The case of a Greek female patient is reported who had a severe, acute, haemolytic episode shortly after commencing dapsone therapy, despite a normal glucose-6-phosphate dehydrogenase (G6PD) screening test. A subsequent quantitative assay revealed reduced levels of G6PD consistent with the heterozygous state. This illustrates that routine screening tests may fail to detect the decreased levels of (G6PD) which occur in female heterozygotes. Since these patients are at risk of severe dapsone-induced haemolysis, the need for quantitative G6PD assays in females from susceptible racial groups is emphasized.

Frequency of glucose-6-phosphate dehydrogenase (G6PD) mutations in Chinese, Filipinos, and Laotians from Hawaii.

In a Hawaii Hereditary Anemia Screening Project, 4,984 participants were tested for glucose-6-phosphate dehydrogenase (G6PD) deficiency by a filter paper blood spot fluorescence test. Abnormal samples and suspected heterozygotes were checked by quantitative G6PD assay (normal 4.5 to 14 units/g Hb). G6PD was deficient (< 1.5 units/g Hb) in 188 of 2,155 males; 7 other males had low activity (1.5 to 2.8 units/g Hb). The gene frequency, estimated from males after excluding referred and related cases, was 0.037 for Chinese, 0.134 for Filipinos, and 0.203 for Laotians. Among 2,829 females tested, family data showed 111 females were obliged to be at least heterozygous, regardless of G6PD activity, and 43 others had low G6PD activity. Most heterozygotes probably remained undetected by G6PD screening. In 28 females, activity was under 10%; in another 9 females, activity was < 1.5 units/g Hb. Since only 25 homozygotes would be predicted, this apparent excess of females with deficient activity could be due to unequal X-inactivation in some heterozygotes. DNA analysis by polymerase chain reaction amplification and special analytic procedures revealed 10 different missense mutations in 75 males. The nucleotide 835 A-->T and 1360 C-->T transitions were first detected in this Hawaiian Project; we found that the nucleotide 1360 mutation was the most common cause of G6PD deficiency in Filipinos. This is the first report of G6PD screening and analysis of molecular G6PD mutations in Filipino and Laotian populations.