Distribution of glucose-6-phosphate dehydrogenase mutations in Southeast Asia

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is a heterogeneous enzyme abnormality with high frequency in tropical areas. We performed population screening and molecular studies of G6PD variants to clarify their distribution and features in Southeast Asia. A total of 4317 participants (2019 males, 2298 females) from 16 ethnic groups in Myanmar, Lao in Laos, and Amboinese in Indonesia were screened with a single-step screening method. The prevalence of G6PD-deficient males ranged from 0% (the Akha) to 10.8% (the Shan). These G6PD-deficient individuals and 12 G6PD-deficient patients who had been diagnosed at hospitals in Indonesia and Malaysia were subjected to molecular analysis by a combination of polymerase-chain-reaction-based single-strand conformation polymorphism analysis and direct sequencing. Ten different missense mutations were identified in 63 G6PD-deficient individuals (50 hemizygotes, 11 heterozygotes, and 2 homozygotes) from 14 ethnic groups. One missense mutation (1291 G-->A) found in an Indonesian Chinese, viz., G6PD Surabaya, was previously unknown. The 487 G-->A (G6PD Mahidol) mutation was widely seen in Myanmar, 383 T-->C (G6PD Vanua Lava) was specifically found among Amboinese, 871 G-->A (G6PD Viangchan) was observed mainly in Lao, and 592 C-->T (G6PD Coimbra) was found in Malaysian aborigines (Orang Asli). The other five mutations, 95 A-->G (G6PD Gaohe), 1003 G-->A (G6PD Chatham), 1360 C-->T (G6PD Union), 1376 G-->T (G6PD Canton), and 1388 G-->A (G6PD Kaiping) were identified mostly in accordance with distributions reported previously.     

The prevalence of factor V Leiden,prothrombin G20210A and methylenetetrahydrofolate reductase polymorphism C677T among G6PD deficient individuals from Western Iran

It has been suggested that the allele frequency of thrombophilic mutations is affected by glucose-6-phosphate dehydrogenase (G6PD) deficiency. The prevalence of thrombophilic mutations were studied in sixty G6PD deficient individuals including 57 males and three females with the mean age of 15 ± 3.08 and 110 age and sex matched healthy individuals consisted of 95 males and 15 females with the mean age of 16.19 ± 2.17 from the Kermanshah Province of Iran. Using a combination of PCR-RFLP technique, single strand conformation polymorphism (SSCP) analysis and DNA sequencing polymorphic G6PD mutations were identified. The factor V Leiden, prothrombin G20210A and methylenetetrahydrofolate reductase (MTHFR) C677T were detected by PCR-RFLP method using MnlI, HindIII and HinfI restriction enzymes, respectively. Three mutations, G6PD Mediterranean, G6PD Chatham and G6PD Cosenza were identified in 60 G6PD deficient individuals with highest prevalence of G6PD Mediterranean (91.6%). In G6PD deficient individuals the prevalence of factor V Leiden tended to be higher (5%) compared to healthy individuals (2.7%). The prevalence of prothrombin G20210A mutation in G6PD deficient individuals was 1.7%. However, in normal subjects the prevalence of this mutation was 2.7%. The frequency of T allele in G6PD deficient individuals were insignificantly higher (29.16%) than those in healthy individuals (26.8%). Our finding indicates that the prevalence of factor V Leiden, prothrombin G20210A and MTHFR C677T in G6PD deficient individuals is not statistically different compared to normal subjects and G6PD deficiency is not associated with these thrombophilic mutations in Western Iran.     

Glucose-6-phosphate dehydrogenase variants in Hawaii.

Sequence analysis has been performed on the DNA of 13 glucose-6-phosphate dehydrogenase (G6PD) deficient males from Hawaii, 6 of Filipino, 6 of Laotian, and 1 of Chinese extraction. Four different mutations were found: A-->T at cDNA nt 835, G-->A at nt 871, C-->T at nt 1360, and G-->A at nt 1388. The mutations at nt 835 and nt 1360 have not been described previously, and the latter, in particular, appears to be relatively common. The nt 1360 mutation changes the same codon as is altered in a previously described mutation, G6PD Andalus.     

At least five polymorphic mutants account for the prevalence of glucose-6-phosphate dehydrogenase deficiency in Algeria

The electrophoretic mobility and level of enzyme activity of glucose-6-phosphate dehydrogenase (G6PD) was established in 100 unrelated Algerian males with G6PD deficiency. DNA from these subjects was analysed for the presence of certain known G6PD mutations by the appropriate restriction enzyme digestion of fragments amplified by the polymerase chain reaction. Where the mutation could not be identified in this way, the samples were subjected to single-strand conformation polymorphism analysis and abnormal fragments were sequenced. In this way, eight different mutations have been identified, of which five are polymorphic and account for 92% of the samples. The most common variants are G6PD A-(46%) and G6PD Mediterranean (23%), both of which were associated with favism. A new polymorphic variant, G6PD Aures, has been identified during the course of this study, whereas another, G6PD Santamaria, has now been established as a polymorphic variant (11%). Thus, G6PD deficiency in Algeria is heterogeneous, suggesting that there has been significant gene flow, both from sub-Saharan Africa and from other parts of the Mediterranean.     

Molecular genetics of the glucose-6-phosphate dehydrogenase (G6PD) Mediterranean variant and description of a new G6PD mutant, G6PD Andalus1361A

Glucose-6-phosphate dehydrogenase (G6PD; E.C.1.1.1.49) deficiency is the most common human enzymopathy; more than 300 different biochemical variants of the enzyme have been described. In many parts of the world the Mediterranean type of G6PD deficiency is prevalent. However, G6PD Mediterranean has come to be regarded as a generic term applied to similar G6PD mutations thought, however, to represent a somewhat heterogeneous group. A C----T mutation at nucleotide 563 of G6PD Mediterranean has been identified by Vulliamy et al., and the same mutation has been found by De Vita et al. in G6PD Mediterranean, G6PD Sassari, and G6PD Cagliari. The latter subjects had an additional mutation, at nucleotide 1311, that did not produce a coding change. We have examined genomic DNA of five patients--four of Spanish origin and one of Jewish origin--having enzymatically documented G6PD Mediterranean. All had both the mutation at nucleotide 563 and that at nucleotide 1311. A sixth sample, resembling G6PD Mediterranean kinetically but with a slightly rapid electrophoretic mobility, was designated G6PD Andalus and was found to have a different mutation, a G----A transition at nucleotide 1361, producing an arginine-to-histidine substitution. These studies suggest that G6PD Mediterranean is, after all, relatively homogeneous.     

Two point mutations are responsible for G6PD polymorphism in Sardinia.

The human X-linked gene encoding glucose 6-phosphate dehydrogenase (G6PD) is highly polymorphic; more than 300 G6PD variants have been identified. G6PD deficiency in different geographical areas appears to have arisen through independent mutational events, but within the same population it may also be heterogeneous. One example is the island of Sardinia, where careful clinical and biochemical studies have identified four different G6PD variants. We cloned and sequenced the four G6PD variants from Sardinia and found that only two mutations are responsible for G6PD deficiency in this area: one mutation is the cause of the G6PD Seattle-like phenotype, a milder form of G6PD deficiency; the other mutation is responsible for all forms of very severe G6PD deficiency in Sardinia and, possibly, in the Mediterranean.     

Origin and spread of the glucose-6-phosphate dehydrogenase variant (G6PD-Mediterranean) in the Middle East.

A common glucose-6-phosphate dehydrogenase (G6PD) variant characterized by severe enzyme deficiency and B-like electrophoretic mobility is called "G6PD-Mediterranean" because it is found in different populations around the Mediterranean Sea. Sequence analysis of Italian subjects has revealed that the molecular basis of G6PD-Mediterranean is a single C-T transition at nucleotide position 563, causing a serine phenylalanine replacement at amino acid position 188. Most G6PD-Mediterranean subjects also have a silent C-T transition (without amino acid replacement) at nucleotide position 1311. Twenty-one unrelated individuals from Saudi Arabia, Iraq, Iran, Jordan, Lebanon, and Israel with both severe G6PD deficiency and B-like electrophoretic mobility were tested for both mutations by using amplification followed by digestion with appropriate restriction enzymes. All but one had the 563 mutation, and, of these, all but one had the 1311 mutation. Another 24 unrelated Middle Eastern individuals with normal G6PD activity or not known to be G6PD deficient were similarly tested. Four had the silent mutation at position 1311 in the absence of the deficiency mutation at position 563. We conclude that (1) the large majority of Middle Eastern subjects with the G6PD-Mediterranean phenotype have the same mutation found in Italy, (2) the silent mutation is an independent polymorphism in the Middle East, with a frequency of about .13, and (3) the mutation leading to the G6PD-Mediterranean deficiency has probably arisen on a chromosome that already carried the silent mutation.     

G6PD-MutDB: a mutation and phenotype database of glucose-6-phosphate (G6PD) deficiency

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is the most common hereditary enzymatic disorder of red blood cells in humans due to mutations in the G6PD gene. The G6PD enzyme catalyzes the first step in the pentose phosphate pathway to protect cells against oxidative stress. Mutations in the G6PD gene will cause functional variants with various biochemical and clinical phenotypes. So far, about 160 mutations along with more than 400 biochemical variants have been described. G6PD-MutDB is a disease-specific resource of G6PD deficiency, collecting and integrating G6PD mutations with biochemical and clinical phenotypes. Data of G6PD deficiency is manually extracted from published papers, focusing primarily on variants with identified mutation and well-described quantitative phenotypes. G6PD-MutDB implements an approach, CNSHA predictor, to help identify a potential chronic non-spherocytic hemolytic anemia (CNSHA) phenotype of an unknown mutation. G6PD-MutDB is believed to facilitate analysis of relationship between molecular mutation and functional phenotype of G6PD deficiency owing to convenient data resource and useful tools. This database is available from http://202.120.189.88/mutdb.     

Prevalence and Molecular Characterization of Glucose-6-Phosphate Dehydrogenase Deficiency at the China-Myanmar Border

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is an X-linked hereditary disease that predisposes red blood cells to oxidative damage. G6PD deficiency is particularly prevalent in historically malaria-endemic areas. Use of primaquine for malaria treatment may result in severe hemolysis in G6PD deficient patients. In this study, we systematically evaluated the prevalence of G6PD deficiency in the Kachin (Jingpo) ethnic group along the China-Myanmar border and determined the underlying G6PD genotypes. We surveyed G6PD deficiency in 1770 adult individuals (671 males and 1099 females) of the Kachin ethnicity using a G6PD fluorescent spot test. The overall prevalence of G6PD deficiency in the study population was 29.6% (523/1770), among which 27.9% and 30.6% were males and females, respectively. From these G6PD deficient samples, 198 unrelated individuals (147 females and 51 males) were selected for genotyping at 11 known G6PD single nucleotide polymorphisms (SNPs) in Southeast Asia (ten in exons and one in intron 11) using a multiplex SNaPshot assay. Mutations with known association to a deficient phenotype were detected in 43.9% (87/198) of cases, intronic and synonymous mutations were detected alone in 34.8% (69/198) cases and no mutation were found in 21.2% (42/198) cases. Five non-synonymous mutations, Mahidol 487G>A, Kaiping 1388G>A, Canton 1376G>T, Chinese 4 392G>T, and Viangchan 871G>A were detected. Of the 87 cases with known deficient mutations, the Mahidol variant was the most common (89.7%; 78/87), followed by the Kaiping (8.0%; 7/87) and the Viangchan (2.2%; 2/87) variants. The Canton and Chinese 4 variants were found in 1.1% of these 87 cases. Among them, two females carried the Mahidol/Viangchan and Mahidol/Kaiping double mutations, respectively. Interestingly, the silent SNPs 1311C>T and IVS11nt93T>C both occurred in the same 95 subjects with frequencies at 56.4% and 23.5% in tested females and males, respectively (P<0.05). It is noteworthy that 24 subjects carrying the Mahidol mutation and two carrying the Kaiping mutation also carried the 1311C>T/IVS11nt93T>C SNPs. Further studies are needed to determine the enzyme levels of the G6PD deficient people and presence of additional G6PD mutations in the study population.     

Genetic heterogeneity of glucose-6-phosphate dehydrogenase deficiency revealed by single-strand conformation and sequence analysis.

We have carried out a systematic study of the molecular basis of glucose-6-phosphate dehydrogenase (G6PD) deficiency on a sample of 53 male subjects from Calabria, in southern Italy. Our sequential approach consisted of the following steps: (1) Partial biochemical characterization was used to pinpoint candidate known variants. The identity of these was then verified by restriction-enzyme or allele-specific oligonucleotide hybridization analysis of the appropriate PCR-amplified fragment. (2) On samples for which there was no obvious candidate mutation, we proceeded to amplify the entire coding region in eight fragments, followed by single-strand conformation polymorphism (SSCP) analysis of each fragment. (3) The next step was M13 phage cloning and sequencing of those individual fragments that were found to be abnormal by SSCP. Through this approach we have identified the molecular lesion in 51 of the 53 samples. In these we found a total of nine different G6PD-deficient variants, five of which (G6PD Mediterranean, G6PD A-, G6PD Coimbra, G6PD Seattle, and G6PD Montalbano) were already known, whereas four are new (G6PD Cassano, G6PD Cosenza, G6PD Sibari, and G6PD Maewo). G6PD Mediterranean is the commonest variant, followed by G6PD Seattle. At least seven of the variants are present, at polymorphic frequencies, in the Calabria region, and some have a nonrandom distribution within the region. This study shows that the genetic heterogeneity of G6PD deficiency in Calabria, when analyzed at the DNA level, is even greater than had been anticipated from biochemical characterization. The sequential approach that we have followed is fast and efficient and could be applied to other populations.     

Glucose-6-phosphate dehydrogenase deficiency in Tunisia: molecular data and phenotype-genotype association

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is the most common human enzyme defect. In this study, we aimed to perform a molecular investigation of G6PD deficiency in Tunisia and to associate clinical manifestations and the degree of deficiency with the genotype. A total of 161 Tunisian subjects of both sexes were screened by spectrophotometric assay for enzyme activity. Out of these, 54 unrelated subjects were selected for screening of the most frequent mutations in Tunisia by PCR/RFLP, followed by size-based separation of double-stranded fragments under non-denaturing conditions on a denaturing high performance liquid chromatography system. Of the 56 altered chromosomes examined, 75 % had the GdA^? mutation, 14.28 % showed the GdB^? mutation and no mutations were identified in 10.72 % of cases. Hemizygous males with GdA^? mutation were mostly of class III, while those with GdB^? mutation were mainly of class II. The principal clinical manifestation encountered was favism. Acute hemolytic crises induced by drugs or infections and neonatal jaundice were also noted. Less severe clinical features such as low back pain were present in heterozygous females and in one homozygous female. Asymptomatic individuals were in majority heterozygote females and strangely one hemizygous male. The spectrum of mutations seems to be homogeneous and similar to that of Mediterranean countries; nevertheless 10.72 % of cases remain with undetermined mutation thus suggesting a potential heterogeneity of the deficiency at the molecular level. On the other hand, we note a better association of the molecular defects with the severity of the deficiency than with clinical manifestations.     

Functional properties of two mutants of human glucose 6-phosphate dehydrogenase, R393G and R393H, corresponding to the clinical variants G6PD Wisconsin and Nashville

Two severe Class I human glucose-6-phosphate dehydrogenase (G6PD, EC1.1.1.49) mutations, G6PD(Wisconsin) (nt1177 C-->G, R393G) and G6PD(Nashville) (nt1178 G-->A, R393H), affect the same codon, altering a residue in the dimer interface close to the "structural" NADP+ site. These mutations are predicted to influence interaction with the bound "structural" NADP+, long supposed to be crucial for enzyme stability. Recombinant proteins corresponding to these mutants have been constructed, expressed and purified to homogeneity. Steady-state kinetic parameters of the mutant enzymes were comparable to those of normal human G6PD, indicating that the mutations do not alter catalytic efficiency drastically. However, investigations of thermostability, urea denaturation, protease digestion, and hydrophobic exposure demonstrated that G6PD R393H is less stable than normal G6PD or R393G, and stability was more NADP+-dependent. Apoenzymes were prepared by removal of "structural" NADP+. Again the G6PD(Nashville) protein was markedly less stable, and its dissociation constant for "structural" NADP+ is approximately 500 nM, about 10 times higher than values for R393G (53 nM) and normal G6PD (37 nM). These results, together with structural information, suggest that the instability of the R393H protein, enhanced by the weakened binding of "structural" NADP+, is the likely cause of the severe clinical manifestation observed for G6PD(Nashville). They do not, however, explain the basis of disease in the case of G6PD(Wisconsin).     

PCR—DGGE法研究葡萄糖-6-磷酸脱氢酶缺乏症基因突变

目的：应用PCR-DGGE法和DNA测序分析云南籍G6PD缺乏症患者基因突变类型和特点、方法应用硝基四氮唑蓝（NBT）纸片法进行G6PD缺乏症定性筛查,G6PD／6PGD比值法验证,应用PCR—DGGE法和DNA测序分析46例云南籍G6PD缺乏症患者基因突变类型和特点。结果：46例云南籍G6PD缺乏症样本中有30例经PCR—DGGE法分析G6PDexon12发现有异常电泳条带,DNA测序证实26例（56、52％）为nt-1388G→A,4例（8.7％）nt-1376G→T．而PCR—DGGE法分析G6PDexon2未发现有异常电泳条带的样本出现。结论：（1）nt-1388G→A（56．52％）、nt-1376G→T（8．7％）是云南省主要的基因突变型也是中国人中最常见的两种突变型,揭示中华民族有着共同的起源;（2）所检样本中未发现nt95A→G。（3）应用PCR—DGGE法结合DNA测序检测G6PD缺乏症患者的基因型,阳性检出率高,方法简便、快捷、灵敏、结果准确可靠。     

A New Glucose-6-Phosphate Dehydrogenase Variant, G6PD Orissa (44 Ala→Gly), is the Major Polymorphic Variant in Tribal Populations in India

Deficiency of glucose-6-phosphate dehydrogenase (G6PD) is usually found at high frequencies in areas of the world where malaria has been endemic. The frequency and genetic basis of G6PD deficiency have been studied in Africa, around the Mediterranean, and in the Far East, but little such information is available about the situation in India. To determine the extent of heterogeneity of G6PD, we have studied several different Indian populations by screening for G6PD deficiency, followed by molecular analysis of deficient alleles. The frequency of G6PD deficiency varies between 3% and 15% in different tribal and urban groups. Remarkably, a previously unreported deficient variant, G6PD Orissa (44 Ala→Gly), is responsible for most of the G6PD deficiency in tribal Indian populations but is not found in urban populations, where most of the G6PD deficiency is due to the G6PD Mediterranean (188 Ser→Phe) variant. The K of G6PD Orissa is fivefold higher than that of the normal enzyme. This may be due to the fact that the alanine residue that is replaced by glycine is part of a putative coenzyme-binding site.     

Molecular characterization of glucose-6-phosphate dehydrogenase deficiency in Jeddah,Kingdom of Saudi Arabia

Background

The development of polymerase chain reaction (PCR)-based methods for the detection of known mutations has facilitated detecting specific red blood cell (RBC) enzyme deficiencies. We carried out a study on glucose-6-phosphate dehydrogenase (G6PD) deficient subjects in Jeddah to evaluate the molecular characteristics of this enzyme deficiency and the frequency of nucleotide1311 and IVS-XI-93 polymorphisms in the glucose-6-phosphate dehydrogenase gene.

Results

A total of 1584 unrelated Saudis (984 neonates and 600 adults) were screened for glucose-6-phosphate dehydrogenase deficiency. The prevalence of glucose-6-phosphate dehydrogenase deficiency was 6.9% (n = 110). G6PD Mediterranean mutation was observed in 98 (89.1%) cases, G6PD Aures in 11 (10.0%) cases, and G6PD Chatham in 1 (0.9%) case. None of the samples showed G6PD A￣ mutation. Samples from 29 deficient subjects (25 males and 4 females) were examined for polymorphism. The association of two polymorphisms of exon/intron 11 (c.1311T/IVS-XI-93C) was observed in 14 (42.4%) of 33 chromosomes studied. This association was found in 9 (31.0%) carriers of G6PD Mediterranean and in 4 (13.8%) carriers of G6PD Aures.

Conclusions

The majority of mutations were G6PD Mediterranean, followed by G6PD Aures and < 1% G6PD Chatham. We conclude that 1311T is a frequent polymorphism in subjects with G6PD Mediterranean and Aures variants in Jeddah.

     

Molecular heterogeneity of the glucose-6-phosphate dehydrogenase deficiency in the Hellenic population

We report results from a systematic study to identify the molecular basis of glucose-6-phosphate dehydrogenase (G6PD) deficiency on a sample of 299 male subjects from the Hellenic population. Our stepwise approach involved partial biochemical characterization and quantitation of the enzyme's activity, MboII restriction endonuclease digestion to identify the G6PD Mediterranean variant, which represents the most frequent G6PD variant in our population and a nonradioactive polymerase chain reaction-single-strand conformation polymorphism methodology for the detection of the underlying molecular defect(s) in the rest of the non-Mediterranean G6PD-deficient individuals. Through this approach, six different G6PD variants were identified (G6PD Mediterranean, G6PD Hermoupolis, G6PD Cassano, G6PD Seattle, G6PD Ierapetra and G6PD Acrokorinthos), two of which were new (G6PD Hermoupolis, G6PD Acrokorinthos). In essence, this study underlines the remarkable genetic heterogeneity of the G6PD deficiency in the Hellenic population, while the finding of the double mutant, G6PD Hermoupolis, may help to outline the relationship and evolution of mutations in the human G6PD locus.     

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.     

G6PD Mediterranean accounts for the high prevalence of G6PD deficiency in Kurdish Jews

The Jews of Kurdistan are a small inbred population with a high incidence of -thalassaemia and glucose-6-phosphate dehydrogenase (G6PD) deficiency. Recently, it was reported that the -thalassaemia in this population shows an unusual mutational diversity; 13 different mutations were identified, of which 4 had not previously been observed in any other population. In contrast, we now report that the G6PD deficiency, which has the highest known incidence in the world, and which affects about 70% of males, is almost entirely attributable to a single widespread mutation, G6PD Mediterranean.     

Amino acid conservation and clinical severity of human glucose-6-phosphate dehydrogenase mutations

More than a hundred naturally occurring mutations of human glucose-6-phosphate dehydrogenase (G6PD) have been identified at the amino acid level. The abundance of distinct mutation sites and their clinical manifestations make this enzyme ideal for structure-function analysis studies. We present here a sequence and structure combined analysis by which the severity of clinical symptoms resulting from point mutations of this enzyme is correlated with quantified degrees of amino acid conservation within 23 G6PD sequences from different organisms. Our analysis verifies, on a quantitative basis, a widely held notion that clinically severer mutations of G6PD usually occur at conserved amino acids. However, marked exceptions to this general trend exist which are most notably revealed by a number of mutations associated with chronic nonspherocytic hemolytic anemia (class I variants). When mapped onto a homology-derived structural model of human G6PD, these class I mutational sites of low amino acid conservation appear to localize in two spatially distinct clusters, both of which are populated with mutations consisting mainly of clinically severer variants (i.e. class I and class II). These results of computer-assisted analyses contribute to a further understanding of the structure-function relationships of human G6PD deficiency.     

Prevalence and Molecular Identification of the Mediterranean Variant Among G6PD-Deficient Sistani and Balouch Males in Southeastern Iran

To determine the prevalence of G6PD deficiency and a Mediterranean mutation among males in southeastern Iran, we studied 1,097 Sistani and Balouch schoolboys. A questionnaire was used to collect demographic data and a history of malaria infection; blood samples were evaluated for G6PD deficiency and the G6PD Mediterranean mutation. Of the 1,097 boys screened, 175 were G6PD deficient (5.8 % of the Sistani boys and 19.3 % of the Balouch boys). The malaria survey indicated that among Balouch subjects, malaria infection was about 14 times that of Sistani subjects. Molecular characterization of G6PD-deficient samples revealed a general frequency of 85.1 % for the Mediterranean variant among all subjects (75 % among Sistani and 86.2 % among Balouch cases). The high prevalence of G6PD deficiency among Balouch populations confirms the hypothesis that the distribution of G6PD deficiency is concordant with the geographic distribution of malaria.