Quantitative neonatal glucose-6-phosphate dehydrogenase screening: distribution, reference values, and classification by phenotype.

OBJECTIVE: To determine enzyme assay reference values for newborns in a Sephardic Jewish population at high risk for glucose-6-phosphate dehydrogenase (G6PD) deficiency. STUDY DESIGN: 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.

Glucose-6-phosphate dehydrogenase laboratory assay: How, when, and why?

Glucose 6-phosphate dehydrogenase (G6PD) deficiency is the most common defect of red blood cells. Although some different laboratory techniques or methods are employed for the biochemical screening, a strict relationship between biochemists, clinicians, and molecular biologists is necessary for a definitive diagnosis. This article represents an overview on the current laboratory tests finalized to the screening or to the definitive diagnosis of G6PD-deficiency, underlying the problems regarding the biochemical and molecular identification of heterozygote females other than those regarding the standardization of the clinical and laboratory diagnostic procedures. Finally, this review is aimed to give a flow-chart for the complete diagnostic approach of G6PD-deficiency.

G6PD deficient alleles and haplotype analysis of human G6PD locus in São Tomé e Príncipe (West Africa).

A population sample from São Tomé e Príncipe (West Africa) was screened for the G6PD-deficient variants A- (376G/202A), Betica (376G/968C), and Santa Maria (376G/542T). G6PD locus haplotype diversity was also investigated using six intragenic RFLPs (FokI, PvuII, BspHI, PstI, BclI, NlaIII) and a (CTT)n microsatellite 18.61 kb within the G6PD locus. The estimated frequencies of the G6PD*B normal allele, the G6PD*A variant (376G), and the G6PD*A- allele were 0.698, 0.194, and 0.108, respectively. G6PD variants Betica and Santa Maria were not found. Similar levels of microsatellite diversity were found on variants G6PD*B and G6PD*A (H = 0.61 and 0.68, respectively), indicating a similar age for both alleles. All G6PD*A- alleles share the RFLP-microsatellite haplotype ++(-)+(-)+/195, the same haplotype described in nearly all the *A-alleles from sub-Saharan, Mexican Mestizo, and Portuguese populations, consistent with a single and recent origin of the G202A mutation on this *A haplotype.

Two distinct Indian G6PD variants G6PD Jamnagar and G6PD Rohini caused by the same 949 G-->A mutation.

Earlier we have reported two G6PD variants viz.; G6PD Jamnagar and G6PD Rohini. The enzymes from both the variants showed altered biochemical properties with mild enzyme deficiency and were classified as unique Class III variants. G6PD Jamnagar was found to be associated with drug-induced hemolytic anemia whereas G6PD Rohini was picked up during a population survey. Subsequent molecular studies on the DNA from both the cases showed the presence of the Kerala-Kalyan (949 G-->A) mutation. Hence, this study besides supporting the fact that biochemically distinct variants could have the same mutation at the molecular level also highlights the importance of molecular characterization of G6PD variants.

Evaluation of DNA damage in leukocytes of G6PD-deficient Iranian newborns (Mediterranean variant) using comet assay.

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is the most common inherited disease, which causes neonatal hemolytic anemia and jaundice. Recent studies of our group showed that the Mediterranean variant of this enzyme (Gd-Md) is the predominant G6PD in Iranian male infants suffering from jaundice; this variant is classified as severe G6PD deficiency. Considering the importance of G6PD reaction and its products NADPH and glutathione (GSH) against oxidative stress, we hypothesized the failure of detoxification of H(2)O(2) in G6PD-deficient white blood cells that could probably induce primary DNA damage. For the evaluation of DNA damage, we analyzed mononuclear leukocytes of 36 males suffering from the Gd-Md deficiency using alkaline single cell gel electrophoresis (SCGE) or comet assay. The level of DNA damage was compared with the level of basal DNA damage in control group represented by healthy male infant donors (of the same age group). Visual scoring was used for the evaluation of DNA damages. The results showed that the mean level of the DNA strand breakage in mononuclear leukocytes of 36 male G6PD-deficient (Gd-Md) infants was significantly higher (P < 0.001) than those observed in the normal lymphocytes. In conclusion, this investigation indicates that the mononuclear leukocytes of the Gd-Md samples may be exposed to DNA damage due to oxidative stress. This is the first report using comet assay for evaluation of DNA damage in severe G6PD deficiency samples.

Field trials of a rapid test for G6PD deficiency in combination with a rapid diagnosis of malaria.

A rapid single-step screening method for detection of glucose-6-phosphate dehydrogenase (G6 PD) deficiency was evaluated on Halmahera Island, Maluku Province, Indonesia, and in Shan and Mon States, Myanmar, in combination with a rapid diagnosis of malaria by an acridine orange staining method. Severe deficiency was detected by the rapid test in 45 of 1126 volunteers in Indonesia and 54 of 1079 in Myanmar, but it was difficult to distinguish blood samples with mild deficiency from those with normal activity. 89 of 99 severely deficient cases were later confirmed by formazan ring method in the laboratory, but 5 with mild and 5 with no deficiency were misdiagnosed as severe. Of the samples diagnosed as mild and no deficiency on-site, none was found to be severely deficient by the formazan method. Malaria patients were simultaenously++ detected on-site in 273 samples on Halmahera island and 277 samples from Shan and Mon States. In Mon State, primaquine was prescribed safely to G6 PD-normal malaria patients infected with Plasmodium vivax and/or gametocytes of P. falciparum. The new rapid test for G6 PD deficiency may be useful for detecting severe cases under field conditions, and both rapid tests combined are can be useful in malaria-endemic areas, facilitating early diagnosis, prompt and radical treatment of malaria and suppression of malaria transmission.

Effect of glucose-6-phosphate dehydrogenase deficiency on neutrophil function.

The bactericidal activity of neutrophils depends primarily on free oxygen radicals released by the activation of NADPH oxidase when neutrophils are stimulated by microorganisms. Severe glucose-6-phosphate dehydrogenase (G6PD) deficiency is associated with decreased NADPH production. Increased susceptibility to recurrent bacterial infections in children with severe neutrophil G6PD deficiency as a consequence of decreased NADPH production has been reported earlier. In this study, the in vitro activity of neutrophils from normal and G6PD-deficient individuals was assessed by measuring the [14C]CO2 released via the hexose monophosphate shunt from radiolabeled [1-14C]-glucose and the nitroblue tetrazolium (NBT) dye reduction test. Our results show that the G6PD activity of neutrophils from 48 individuals, identified as severely erythrocyte (RBC) G6PD deficient (< 2 U/10(12) RBC) was 23% of the enzyme activity of neutrophils from 53 individuals with normal RBC G6PD levels (98.8 U/10(12) RBC). However, the results of functional assays of neutrophils as measured by hexose monophosphate shunt and the NBT test were comparable in G6PD-deficient and normal individuals, suggesting that a reduced activity of G6PD to as low as 23% of normal does not affect neutrophil function.

[Molecular analysis of glucose-6-dehydrogenase deficiency in Spain]. / Análisis molecular del déficit de glucosa-6-fosfato deshidrogenasa (G6PD) en España.

PURPOSE: G6PD deficiency is the most frequent enzymopathy-producing genetic polymorphism in humans. Up to now, over 400 putative variants of G6PD have been distinguished on the basis of biochemical characterization of the deficient enzyme. Analysis of the G6PD gene has made possible a precise classification of the G6PD molecular variants by identification of about 80 different point mutations causing much of the phenotypic heterogeneity. In the Spanish population, the analysis of G6PD has led to the identification of 15 different point mutations that underlay the phenotypic heterogeneity of G6PD previously reported by biochemical analysis. The purpose of the study has been to identify the genetic mutation responsible of the G6PD deficiency and to improve the knowledge of its genetic homogeneity. PATIENTS AND METHODS: From 50 Spanish males with G6PD deficiency 34 came from out consultation and 16 from the Spanish Study Group on Red Cell Pathology (GEHBTA-Eritropatología) The methods employed included screening of prevalent mutations by ER-PCR, SSCP-PCR, genetic segmentation and biochemical characterization of the deficient enzyme. RESULTS: In 31 cases the mutations were characteristic of the four most frequent polymorphic variants found in Spain (G6PD A-376G/202A, G6PD Mediterranean 563T G6PD Union 1360T and G6PD Seattle 344C). Since these mutations either create or abolish a specific site recognized by a restriction endonuclease (RE), they can be rapidly detected by RE digestion of a PCR-amplified product (PCR-RE). In patients where none of these mutations were present (17 cases), the G6PD gene was subjected to PCR single-strand conformation polymorphism (PCR-SSCP) analysis combined with direct PCR-sequencing. By using this procedure, 9 new mutations have been identified, five of them have been also found in other geographical areas and were associated with favism (G6PD A-376G/968C, G6PD Santamaria 376G/542T, G6PD Aures 143C and G6PD Chatham 1003A) or chronic haemolytic anaemia (G6PD Tomah 1153C). The other four mutations are unique and not reported so far: Three of them are associated with favism (G6PD Málaga 542T, G6PD Murcia 209G and G6PD Valladolid 406T) and one with chronic haemolytic anaemia (G6PD Madrid 1155G). The remaining eight cases are under study. CONCLUSION: The present study confirms the marked genetic heterogeneity of G6PD deficiency in Spain and demonstrate that the PCR-RE analysis is an easy tool for rapid diagnosis of the molecular defect in subjects with the common forms of G6PD deficiency. Furthermore the fact that G6PD A-376G/202A is the most common variant within Spanish population and the finding of G6PD Aures 43C and G6PD Santamaría 76G/542T, who are polymorphic in Algeria is consistent with a significant gene flow from Africa to Europe through Spain.

Three new exon 10 glucose-6-phosphate dehydrogenase mutations.

Three previously undescribed mutations of the glucose-6-phosphate dehydrogenase (G6PD) gene have been documented in patients with hereditary non-spherocytic hemolytic anemia (HNSHA). In none of the cases have we been able to obtain a sufficient volume of blood to characterize the residual enzyme biochemically. "G6PD Calvo Mackenna" was due to an A-->G transition in cDNA nucleotide 1138 creating an Aat II site and resulting in a substitution of valine for isoleucine at amino acid 380. "G6PD Riley" was due to a T-->C transition at cDNA nucleotide 1139 also changing the 380 isoleucine, in this case to a threonine. "G6PD Wisconsin" was due to an C-->G transversion in cDNA nucleotide 1177, destroying a Aci I site and resulting in a substitution of glycine for arginine at amino acid 393. All of these mutations were in exon 10, where mutations that cause HNSHA appear to be clustered. We present a list of the 83 mutations of G6PD that have been documented to the end of April, 1995.

Molecular analysis of G6PD variants in northern Italy: a study on the population from the Ferrara district.

In the Ferrara district, an area south of the Po delta, four different variants of glucose-6-phosphate dehydrogenase (G6PD;E.C.1.1.49) have been described as a result of biochemical characterization of the enzyme protein: one was G6PD Mediterranean (G6PD Med) and three were local variants named Ferrara I, II, and III. The Ferrara I variant was recently analysed at the DNA level and shown to correspond to G6PD A376G/202A, while the mutations causing the variants II and III, still remain unknown. We analysed the G6PD coding region of 18 apparently unrelated G6PD deficient subjects, whose families have lived in the Ferrara district for at least three generations: 12 subjects had G6PD Med563T/1311T, 3, G6PD Santamaria376G/542T and 2, G6PD A-376G/202A. In one subject we found a new mutation, a G-->A transition at nucleotide 242 causing an Arg-->His amino-acid replacement at position 81. We named this new variant G6PD Lagosanto242 A. Phenotypically the enzyme has nearly normal kinetic properties and appears different from the variants Ferrara II and III.

Cataracts in glucose-6-phosphate dehydrogenase deficiency.

Glucose-6-phosphate dehydrogenase (G-6-PD) deficiency plays an important biochemical role in the metabolism of the lens. Controversies exist in the literature on the possible association between G-6-PD deficiency and the development of cataracts. The authors present ten patients, aged between infancy and 40 years of age, who were admitted for bilateral congenital or presenile cataracts. These patients had no ocular or systemic disease which might have caused their cataract. The only systemic finding they had was G-6-PD deficiency. Two other patients among the families described suffered from bilateral congenital or presenile cataracts with no G-6-PD deficiency. This deficiency state does not appear to play a role in the production of their cataracts.

Molecular characterization of glucose-6-phosphate dehydrogenase variants from Brazil.

Electrophoretic surveys of 7794 individuals from different regions of Brazil and a study of subjects with hemolytic anemia have disclosed 9 putative G6PD variants in addition to the B, A, A-, and Mediterranean types. No variants were found among the 3739 Brazilian Indians tested. Four variants underwent DNA analysis. Three were identified with the Mediterranean, Seattle, and Anaheim types, but the fourth variant was previously undescribed and we propose to designate it G6PD São Borja.

Panorama de la deficiencia de la glucosa-6-fosfato deshidrogenasa eritrocítica / Current status of erythrocytic glucose-6-phosphate dehydrogenase deficiency

La clonación y secuenciamiento del gen de la G6PD abrió un nuevo capítulo en la caracterización de las numerosas variantes enzimáticas de la G6PD. Muchos tipos que se creían diferentes en base a su cinética son en realidad las mismas y se ha encontrado heterogeneidad en algunas que se creían muy homogéneas. Se discute con cierto detalle las variantes A+, A- y mediterránea que tienen una distribución mundial muy alta y sobre las que hay bastante información reciente.

[Overview of erythrocyte glucose-6-phosphate deficiency]. / Panorama de la deficiencia de la glucosa-6-fosfato deshidrogenasa eritrocítica.

The cloning and sequencing of the G6PD gene has opened a new chapter in the characterization of the numerous G6PD variants described. Many which were thought to be different on the basis of their kinetic properties, are really the same whereas heterogeneity has been found in some which were thought to be homogeneous. We discuss with some detail variants A+, A- and the Mediterranean type.

[Relative frequency of glucose-6-phosphate dehydrogenase deficiency in jaundiced newborn infants in the metropolitan area of Monterrey, Nuevo León]. / Frecuencia relativa de la deficiencia de glucosa-6-fosfato deshidrogenasa (G6PD) en neonatos ictéricos del área metropolitana de Monterrey, Nuevo León.

In order to estimate the frequency of G6PD deficiency in the icteric population of the Monterrey metropolitan área (MMA), in the state of Nuevo León, there were studied 829 newborn males were studied. It was found that 13 subjects were deficient of this enzyme, that is equivalent to a frequency of 1.57% and when this frequency was compared with the one that was found an a previous study in a random sample of newborn males (0.66%) no statistical difference was observed, but it was estimated that the icteric newborn males have a relative risk of 2.34 times higher than the population in general to be a G6PD deficient, and this fact suggests the necessity to establish this screening test as a routine for all icteric newborn males, in order to have an opportune detection and an appropriate counselling.

Classification of glucose-6-phosphate dehydrogenase variants by multivariate statistical analysis.

Using principal component analysis a two-dimensional presentation of kinetic parameters from various G6PD-variants was obtained from which similarities between individual enzymes became detectable. Conclusions could be drawn as to how far the kinetic parameters contribute to the discrimination between different variants. An objective classification of G6PD-variants was achieved by application of cluster analysis. The proposed methods provide an effective means for differential elucidation of G6PD-variants and other heterogeneous enzymopathies.

[Classification of glucose-6-phosphate dehydrogenase enzymopathies: evaluation of kinetic parameters using multivariate methods]. / Klassifizierung von Glucose-6-Phosphatdehydrogenase-Enzymopathien: Auswertung kinetischer Parameter mittels multivariater Methoden.

The dependence between 9 kinetic parameters of glucose-6-phosphate dehydrogenase from 13 normal controls and 78 G6PD-deficient patients from the GDR and other socialist countries has been investigated by multivariate statistical methods. Using principal component analysis a two-dimensional presentation of the data was obtained from which similarities between individual enzyme variants became detectable. Conclusions could be drawn in how as far the kinetic parameters contribute to the discrimination between different variants. An objective classification of G6PD-variants was achieved by application of cluster analysis. The proposed methods provide an effective means for differential elucidation of G6PD-enzymopathies and should be also useful in the case of other enzymopathies.