A to G substitution identified in exon 2 of the G6PD gene among G6PD deficient Chinese

Glucose-6-phosphate dehydrogenase (G6PD) mutations database: review of the "old" and update of the new mutations

In the present paper we have updated the G6PD mutations database, including all the last discovered G6PD genetic variants. We underline that the last database has been published by Vulliamy et al. [1] who analytically reported 140 G6PD mutations: along with Vulliamy's database, there are two main sites, such as http://202.120.189.88/mutdb/ and www.LOVD.nl/MR, where almost all G6PD mutations can be found. Compared to the previous mutation reports, in our paper we have included for each mutation some additional information, such as: the secondary structure and the enzyme 3D position involving by mutation, the creation or abolition of a restriction site (with the enzyme involved) and the conservation score associated with each amino acid position. The mutations reported in the present tab have been divided according to the gene's region involved (coding and non-coding) and mutations affecting the coding region in: single, multiple (at least with two bases involved) and deletion. We underline that for the listed mutations, reported in italic, literature doesn't provide all the biochemical or bio-molecular information or the research data. Finally, for the "old" mutations, we tried to verify features previously reported and, when subsequently modified, we updated the specific information using the latest literature data.

Decreased Glucose-6-PhosphateDehydrogenase (G6PD) Activity and Risk of Senile Cataract in Taiwan

G6PD deficiency may render afflicted individuals more susceptible to certain degenerative diseases. To clarify the relationship between G6PD deficiency and cataract, blood G6PD activity was determined in patients with cataract in Taiwan. The cases and hospital-based controls were recruited from the medical outpatient department and from the physical checkup department at Chang Gung Memorial Hospital, respectively. A questionnaire survey was used to determine associations between cataracts and their risk factors. G6PD activity in fresh RBC was quantitatively measured and genomic DNA was extracted from lymphocyte nuclei. The mean blood G6PD activity among cataract patients (278.1 U/10[12] RBC) was similar to that of normals (288.0 U/10[12] RBC). No statistically significant difference in the distribution of G6PD activities as grouped by an increment of 100 U/[10, 12] RBC was observed between cataract patients and normal subjects. The predominant forms of G6PD gene mutation (cDNA 1376 G to T and 95 A to G) were both found in the patients with cataract. The adjusted odds ratio for cataract was 1.21 for every decrement of 100 U/10[12] RBC of G6PD activity in these subjects. These data indicate that G6PD activity is not a potential risk factor for senile cataract in Taiwan.

Three mutations analysis of glucose-6-phosphate dehydrogenase deficiency in neonates in South-west China

BACKGROUND

Glucose-6-phosphate dehydrogenase (G6PD) deficiency, one of the most common human enzymatic defects, is characterized by extreme molecular and biochemical heterogeneity. The underlying DNA changes associated with G6PD deficiency in Asian subjects have not been extensively investigated.

METHODS

Three gene mutations (G1388A, G1376T, A95G, corresponding amino acid change: Arg463His, Arg459Leu, His32Arg, respectively) were examined in 240 G6PD-deficient subjects originating from South-west China using specific polymerase chain reaction.

RESULTS

Of the 240 patients with G6PD deficiency, 190 were found to have the G1388A mutation, 48 had G1376T and two had A95G. There were no significant differences between the clinical manifestations caused by the former two gene mutations, which both cause acute hemolytic anemia and jaundice. Therefore the most common gene mutations of G6PD deficiency in neonates in South-west China are G1388A and G1376T mutations.

CONCLUSION

It is suggested that G6PD deficiency screening be done in higher risk neonates with jaundice in qualified hospitals as soon as possible.

Decreased blood activity of glucose-6-phosphate dehydrogenase associates with increased risk for diabetes mellitus

Glucose-6-phosphate dehydrogenase (G6PD) deficiency predisposes affected individuals highly susceptible to oxidative stress, which is one of the risk factors for diabetes. To evaluate the relationship between blood level of G6PD activity and diabetes in Taiwan, blood G6PD activity was analyzed among 237 patients with diabetes and 656 healthy subjects. A significant difference in the distribution of G6PD activities as grouped by an increment of 100 U/10(12) red blood cells (RBCs) was observed between diabetic patients and healthy subjects. The odds ratio for diabetes was 1.46 (95% confidence interval = 1.11-1.92) for every decrement of 100 U/10(12) RBC G6PD activities in these subjects. The data indicate that low G6PD activity is another risk factor for diabetes.

Free Radical and Oxidative Damage in Human Blood Cells

Free radicals and oxidative damage play important roles in aging and many degenerative disorders such as cancer, cardiovascular diseases, and Alzheimer disease. Antioxidants can alleviate some of the harmful effects of oxidative damage. In this report, we describe that we have been using human red blood cells (RBCs) as a model system to delineate the effects of oxidative damage on human cells, particularly on glucose-6-phosphate dehydrogenase (G6PD)-deficient human RBCs. By using a monolayer technique, we found that oxidative denaturation of hemoglobin leads to the release of hemin into the RBC membrane and the released hemin is capable of oxidizing membrane proteins via a thiyl radical intermediate as detected by the electron spin resonance technique. By using a Laser Viscodiffractometer (Vidometer) to measure RBC deformability, we found that the deformability of G6PD-deficient RBCs was drastically reduced by hydroxyl radicals. Perhaps as a consequence of enhanced susceptibility to oxidative stress, G6PD-deficient individuals have lower antioxidant levels, particularly vitamin C, than normal individuals. Interestingly, we have also found that RBC deformability could be affected by two environmental pollutants, namely, platinum and palladium, which can enhance hydroxyl radical formation in the presence of hydrogen peroxide and ferrous ion (Fenton reaction).

A new glucose 6 phosphate dehydrogenase variant G6PD Sinnai (34 G-->T). Mutations in brief no. 156. Online

In this paper we report a male infant heterozygous for thalassemia with a mild glucose 6 phosphate dehydrogenase deficiency. The molecular basis of this new Class III G6PD variant is a G-->T mutation at nucleotide 34 in the exon 2, which predicts a Val-->Leu aminoacid substitution at codon 12. We designated this variant as G6PD Sinnai from the place of birth of the propositus.

Red blood cell enzymes and their clinical application

Red blood cell enzyme activities are measured mainly to diagnose hereditary nonspherocytic hemolytic anemia associated with enzyme anomalies. At least 15 enzyme anomalies associated with hereditary hemolytic anemia have been reported. Some nonhematologic disease can also be diagnosed by the measurement of red blood cell enzyme activities in the case in which enzymes of red blood cells and the other organs are under the same genetic control. Progress in molecular biology has provided a new perspective. Techniques such as the polymerase chain reaction and single-strand conformation polymorphism analysis have greatly facilitated the molecular analysis of erythroenzymopathies. These studies have clarified the correlation between the functional and structural abnormalities of the variant enzymes. In general, the mutations that induce an alteration of substrate binding site and/or enzyme instability might result in markedly altered enzyme properties and severe clinical symptoms.

Molecular basis of erythroenzymopathies associated with hereditary hemolytic anemia: tabulation of mutant enzymes

Molecular abnormalities of erythroenzymopathies associated with hereditary hemolytic anemia have been determined by means of molecular biology. Pyruvate kinase (PK) deficiency is the most common and well-characterized enzyme deficiency in the glycolytic pathway, and it causes hereditary hemolytic anemia. To date, 47 gene mutations have been identified. We identified one base deletion, one splicing mutation, and six distinct missense mutations in 12 unrelated families with a homozygous PK deficiency. Mutations located near the substrate or fructose-1,6- diphosphate binding site may change the conformation of the active site, resulting in a drastic loss of activity and severe clinical symptoms. Glucose-6-phosphate dehydrogenase (G6PD)deficiency is the most common metabolic disorder, and it is associated with chronic hemolytic anemia and/or drug- or infection-induced acute hemolytic attack. An estimated 400 million people are affected worldwide. The mutations responsible for about 78 variants have been determined. Some have polymorphic frequencies in different populations. Most variants are produced by one or two nucleotide substitutions. Molecular studies have disclosed that most of the class 1 G6PD variants associated with chronic hemolysis have the mutations surrounding either the substrate or the NADP binding site. Among rare enzymopathies, missense mutations have been determined in deficiencies of glucosephosphate isomerase, (TPI), phosphoglycerate kinase, and adenylate kinase. Compound heterozygosity with missense mutation and base deletion has been determined in deficiencies of hexokinase and diphosphoglyceromutase. Compound heterozygosity with missense and nonsense mutations has been identified in TPI deficiency. One base junction mutations resulting in abnormally spliced PFK-M mRNA have been identified in homozygous PFK deficiency. An exception is hemolytic anemia due to increased adenosine deaminase activity. The basic abnormality appears to result from the overproduction of a structurally normal enzyme.

Molecular basis of glucose-6-phosphate dehydrogenase (G6PD) deficiency in three Taiwan aboriginal tribes

We have investigated glucose-6-phosphate dehydrogenase (G6PD) deficiency in 220 unrelated aboriginal male subjects who belong to three different tribes (Saisiat, Ami, and Yami) in Taiwan. Our results show that the G6PD deficiency rates for Saisiat, Ami, and Yami people are 9.0% (6/67), 6.1% (6/99), and 0% (0/54), respectively. Among these deficiency cases, 4 of 6 (66.7%) Saisiat subjects have the 493 A-->G mutation and one carries the 1376 G-->T mutation, whereas, in Ami subjects, we found that four of six (66.7%) affected males have the 592 C-->T mutation and one carries the 493 A-->G mutation. These results contrast with our previous findings for Taiwan Chinese, in whom the 1376 G-->T mutation is the major mutant allele and accounts for 52.3% of the deficiency cases. This is the first report of G6PD deficiency characterized at the DNA level in Taiwan aboriginal populations.

Molecular characterisation of red cell glucose-6-phosphate dehydrogenase deficiency in Singapore Chinese

Sixty-two G6PD deficient Chinese males have been investigated for the presence of seven mutations of the coding region of the G6PD gene by natural and artificially created amplified restriction sites. The results show that the G to T substitution at nucleotide (nt) 1376 and G to A substitution at nt 1388 represent 24% and 21% of G6PD deficiency, respectively, in the Singapore Chinese; 37% of the sample could not be characterised. The remaining samples were identified as follows: 10% C-->T at nt 563, 5% A-->G at nt 95, and 3% C-->T at nt 1024. The G to A substitution (nt 487) and the substitution A-->G (nt 493) were not present in this sample. None of the subjects with the Mediterranean mutation (563 C-->T) had the silent mutation at 1311 (C-->T). This study confirms the extreme molecular heterogeneity of the G6PD gene in the Chinese.

Variants of glucose-6-phosphate dehydrogenase are due to missense mutations spread throughout the coding region of the gene

Glucose-6-phosphate dehydrogenase (G6PD) is remarkable for its genetic diversity in humans. Many variants of G6PD have been described with wide ranging levels of enzyme activity and associated clinical symptoms. Fifty-eight different mutations have now been identified and these account for 97 named G6PD variants. The mutations are almost exclusively missense mutations, causing single amino acid substitutions. They are spread throughout the coding region of the gene, although there appears to be a cluster of mutations that cause a more severe clinical phenotype towards the 3' end of the gene. The absence of large deletions, frameshift mutations and nonsense mutations is consistent with the notion that a total lack of G6PD activity would be lethal.

Study of glucose-6-phosphate dehydrogenase: history and molecular biology

Glucose-6-phosphate dehydrogenase (G6PD) deficiency was discovered in the 1950s. The history of the development of knowledge about G6PD deficiency is reviewed here. In the first decade after its discovery, the clinical manifestations of G6PD deficiency began to be understood. In the second decade, attention was focused on the degree of variability of this enzyme and the distinction of the various biochemical variants from one another. In the last decade, it has been possible to understand the mutations that effect this enzyme at the DNA level. Some 40 different mutations have now been characterized. Analysis of these mutations indicates that, while diversity sometimes exists within a mutation considered biochemical homogeneous, more often variants thought to be distinct prove to be identical. The study of G6PD mutations is beginning to provide insight into structure-function relationships.