Comparison for functional aberration of G-6-PD deficiency variants with exon 10 mutations

Abstract

Glucose-6-phosphate dehydrogenase (G-6-PD) deficiency is a common inherited enzyme deficiency in many parts of the world and there are many different variants described. Every G-6-PD deficiency variant has a unique underlying genetic defect, therefore it manifests specific properties. The single amino acid substitution in the globin chain is the commonest form of G-6-PD deficiency variant. Usually, the G-6-PD deficiency variant with the pathogenesis of a single amino acid substitution presents with only one aberration in secondary structure. Although many G-6-PD deficiency variants present similar structural abnormal points their functions sometimes are discordant. Here, the author performed a functional analysis on some alpha haemoglobinopathies using a novel bioinformatic tool, Polyphen. The mutations of five G-6-PD deficiency variants with exon 10 mutations, Guadalajara (386 Arg?Cys), Beverly Hills (387 Arg?His), Serres (361 Ala?Val), Iowa (385 Lys?Glu), and Clinic (405 Met?Ile) were selected for further study in this investigation. According to the in silico mutation study, the functional change in the G-6-PD deficiency variants with exon 10 mutations studied is variable. Here, it indicates that the functional aberration in the G-6-PD deficiency variant is based on complex pathogenesis. The identification of the structural aberration only in a G-6-PD deficiency variant is not sufficient and should be supplemented with a further functional analysis for a better insight in this topic.     

Comparison for functional aberration of G-6-PD deficiency variants with exon 10 mutations

Glucose-6-phosphate dehydrogenase (G-6-PD) deficiency is a common inherited enzyme deficiency in many parts of the world and there are many different variants described. Every G-6-PD deficiency variant has a unique underlying genetic defect, therefore it manifests specific properties. The single amino acid substitution in the globin chain is the commonest form of G-6-PD deficiency variant. Usually, the G-6-PD deficiency variant with the pathogenesis of a single amino acid substitution presents with only one aberration in secondary structure. Although many G-6-PD deficiency variants present similar structural abnormal points their functions sometimes are discordant. Here, the author performed a functional analysis on some alpha haemoglobinopathies using a novel bioinformatic tool, Polyphen. The mutations of five G-6-PD deficiency variants with exon 10 mutations, Guadalajara (386 Arg-->Cys), Beverly Hills (387 Arg-->His), Serres (361 Ala-->Val), Iowa (385 Lys-->Glu), and Clinic (405 Met-->Ile) were selected for further study in this investigation. According to the in silico mutation study, the functional change in the G-6-PD deficiency variants with exon 10 mutations studied is variable. Here, it indicates that the functional aberration in the G-6-PD deficiency variant is based on complex pathogenesis. The identification of the structural aberration only in a G-6-PD deficiency variant is not sufficient and should be supplemented with a further functional analysis for a better insight in this topic.     

Molecular heterogeneity of glucose-6-phosphate dehydrogenase deficiency in Mexico: overall results of a 7-year project

Several years ago, a project aiming to determine (i) the molecular basis of G-6-PD deficiency, (ii) the distribution of four different mutant alleles previously detected, and (iii) the whole of polymorphic alleles that account for the overall prevalence of G-6-PD deficiency in Mexico was implemented. Nearly 5000 individuals-from the general population and patients with hemolytic anemia-belonging to at least 14 States were screened for G-6-PD deficiency. Seventy-six G-6-PD-deficient subjects were detected and the prevalence of G-6-PD deficiency in 4777 individuals from the general population was 0.71%. Screening for both mutations associated with enzyme deficiency and silent polymorphisms at the G-6-PD gene was performed in the enzyme-deficient individuals by PCR-SSCP combined with restriction enzyme analysis; the silent polymorphisms as well as the nondeficient variant G-6-PD A(376G) were also investigated in 366 G-6-PD normal individuals from the general population. In 88% of the enzyme-deficient individuals it was possible to define the mutation responsible and the type G-6-PD A- variants were the more common in both individuals from the general population and patients with hemolytic anemia. G-6-PD deficiency is heterogeneous at the DNA level in Mexico and up to date 10 different variants-8 in the present project and 2 previously-have been observed: G-6-PD A(-202A/376G), G-6-PD A(-376G/968C), G-6-PD Santamaria(376G/542T), G-6-PD Vanua Lava(383C), G-6-PD Tsukui(del561-563), G-6-PD "Mexico City"(680A), G-6-PD Seattle(844C), G-6PD Guadalajara(1159T),G-6-PD Nashville(1178A), and G-6-PD Union(1360T). The G-6-PD A(-) variants have a relatively homogeneous distribution and along with G-6-PD Santamaria(376G/542T), they account for 82% of the overall prevalence of G-6-PD deficiency in Mexico; all other seven variants represent 9% of the mutant alleles examined, and in the rest of the chromosomes the mutation responsible for the enzyme deficiency remains to be defined. Several of the variants observed in Mexico are common in Africa, South Europe, and Southeast Asia. The prevalence for the variant G-6-PD A(376G) was 1.64%. From 256 possible haplotypes only 14 were observed and haplotype analysis suggests that some of the G-6-PD variants probably were imported to Mexico by population flow from South Europe, Africa, and Southeast Asia. This work (i) identified the G-6-PD variants prevalent in Mexico, (ii) defines their geographical distribution, (iii) contributes to the knowledge of the genetic structure of the Mexican population, and (iv) will facilitate the molecular analysis of the G-6-PD gene in enzyme-deficient Mexican individuals.     

Glucose-6-phosphate dehydrogenase mutations and haplotypes in Mexican Mestizos

In a screening for glucose-6-phosphate dehydrogenase (G-6-PD) deficiency in 1985 unrelated male subjects from the general population (Groups A and B) belonging to four states of the Pacific coast, 21 G-6-PD-deficient subjects were detected. Screening for mutations at the G-6-PD gene by PCR-restriction enzyme in these 21 G-6-PD-deficient subjects as well as in 14 G-6-PD-deficient patients with hemolytic anemia belonging to several states of Mexico showed two common G-6-PD variants: G-6-PD A-(202A/376G) (19 cases) and G-6-PD A-(376G/968C) (9 cases). In 7 individuals the mutations responsible for the enzyme deficiency remain to be determined. Furthermore, four silent polymorphic sites at the G-6-PD gene (PvuII, PstI, 1311, and NlaIII) were investigated in the 28 individuals with G-6-PD A- variants and in 137 G-6-PD normal subjects. As expected, only 10 different haplotypes were observed. To date, in our project aiming to determine the molecular basis of G-6-PD deficiency in Mexico, 60 unrelated G-6-PD-deficient Mexican males-25 in previous studies and 35 in the present work-have been studied. More than 75% of these individuals are from states of the Pacific coast (Sinaloa, Nayarit, Jalisco, Michoacán, Guerrero, Oaxaca, and Chiapas). The results show that although G-6-PD deficiency is heterogeneous at the DNA level in Mexico, only three polymorphic variants have been observed: G-6-PD A-(202A/376G) (36 cases), G-6-PD A-(376G/968C) (13 cases), and G-6-PD Seattle(844C) (2 cases). G-6-PD A- variants are relatively distributed homogeneously and both variants explain 82% of the overall prevalence of G-6-PD deficiency. The variant G-6-PD A-(202A/376G) represents 73% of the G-6-PD A- alleles. Our data also show that the variant G-6-PD A-(376G/968C)-which has been observed in Mexico in the context of two different haplotypes-is more common than previously supposed. The three polymorphic variants that we observed in Mexico are on the same haplotypes as found in subjects from Africa, the Canary Islands, and Spain.     

G-6-PD Walter Reed: possible insight into "structural" NADP in G-6-PD

A new G-6-PD variant, G-6-PD Walter Reed, causing hereditary nonspherocytic hemolytic anemia is characterized. This variant is unusual in that its stability requires the presence of high concentrations of NADP, while its Km for NADP is normal. This finding is consistent with the suggestion that G-6-PD has two separate binding sites, a high affinity "structural" site and a lower affinity catalytic site. The mutation in G-6-PD Walter Reed, like that of the previously described variant, G-6-PD Torrance, may be due to a mutation of the "structural" site for NADP.     

Three new variants of glucose-6-phosphate dehydrogenase associated with chronic nonspherocytic hemolytic anemia: G-6-PD Lincoln Park, G-6-PD Arlington Heights, and G-6-PD West Town

Glucose-6-phosphate dehydrogenase (G-6-PD) deficiency was identified in three children who were evaluated because of chronic nonspherocytic hemolytic anemia. One child is of German extraction, another Puerto Rican, and the third Mexican. In each of the patients the hemolytic process was well compensated, but each had one or more episodes of anemia following exposure to an oxidant drug or with infections. The electrophoretic, functional, and kinetic properties of the mutant enzymes, derived both from the patients' erythrocytes and from cultured fibroblasts, allowed each to be distinguished from G-6-PD variants previously described.     

G-6-PD Long Prairie: a new glucose-6-phosphate dehydrogenase mutant exhibiting normal sensitivity to inhibition by NADPH and accompanied by nonspherocytic hemolytic anemia.

The enzymatic properties of a new glucose-6-phosphate dehydrogenase (G-6-PD) variant (G-6-PD Long Prairie) were studied in a white patient with chronic nonspherocytic hemolysis. The red cells were found to have 2.3%-7.7% normal enzymatic activity. The mutant enzyme exhibited marked heat instability, an increased pH optimum, a moderately decreased Km for G-6-P, and increased utilization of 2-deoxyglucose-6-phosphate and deamino NADP. The Km for NADP and Ki for NADPH were both normal. G-6-PD Long Prairie is an interesting new G-6-PD variant that demonstrates that chronic hemolysis can be associated with modestly decreased G-6-PD activity despite normal sensitivity to inhibition by NADPH. Although increased sensitivity to inhibition by NADPH has been postulated to decrease intracellular enzyme activity, resulting in enhanced susceptibility to hemolysis in certain G-6-PD variants with only moderately decreased enzymatic activity, an alternative mechanism of hemolysis, possibly enzyme thermolability, exists in G-6-PD Long Prairie.     

A new glucose 6-phosphate dehydrogenase variant (G-6-PD Verona) in a patient with myelodysplastic syndrome

A 67-year-old woman investigated because of 'myelodysplastic syndrome' was found to have a 4-fold increase in G-6-PD activity in her erythrocytes. The enzyme was partially purified and characterized. On grounds of: (a) reduced electrophoretic mobility, (b) abnormal cathodic band(s) in isoelectrofocusing, (c) increased Michaelis constant for glucose 6-phosphate, (d) abnormal thermostability, and (e) abnormal interaction with the ligand NADPH, we conclude that this is a new structural variant which we designate G-6-PD Verona. G-6-PD Verona was the sole apparent source of G-6-PD activity in the patient's erythrocytes; by contrast, the patient's fibroblasts had only normal G-6-PH (type B). The patient's haematological course terminated into acute myeloid leukaemia. We believe G-6-PD Verona was the result of a somatic mutation in an X-chromosome which took place in a haemopoietic cell clone which subsequently underwent neoplastic transformation.     

Expression of two G-6-PD genes in an XX phenotypic male

The glucose-6-phosphate dehydrogenase (G-6-PD) gene is located on the X-chromosome. Normal males have a single gene and produce a single G-6-PD type, while normal XX females may be heterozygotes for two different G-6-PD genes. We report the case of a phenotypic male who was found to be heterozygous for two G-6-PD enzymes. Cytogenetic analysis showed that he was a 46,XX male.     

Mechanism of hemolysis of G-6-PD deficient red cells: changes in membrane lipids and polypeptides

Summary A study of red cell membrane polypeptide and lipid profiles in G-6-PD deficient subjects has been made. High membrane spectrin and lipid content was demonstrated in the red cells of drug sensitive G-6-PD deficient individuals, while it was normal in non-sensitive G-6-PD deficient subjects. An inverse relationship was observed between GSH level and spectrin content in the former group. Possible mechanism of increased spectrin content in relation to hemolysis is discussed.     

Erythrocytosis due to bisphosphoglycerate mutase deficiency with concurrent glucose-6-phosphate dehydrogenase (G-6-PD) deficiency

A 28-year-old asymptomatic male of Iranian Jewish (Meshadi) heritage was found on routine exam to have an erythrocytosis (RBC = 6.22 x 10(12)/l, Hgb = 19.2 g/dl, Hct = 58.9%). Splenomegaly was absent on physical exam. There was no family history of erythrocytosis. His oxygen dissociation curve was left-shifted with a p50 of 19 mmHg (normal = 25-32 mmHg). Hemoglobin electrophoresis showed no abnormalities. DNA sequencing of the hemoglobin beta globin gene and both alpha globin genes did not reveal a mutation. A 2,3-bisphosphoglycerate (BPG) level was markedly decreased at 0.3 micromol/g Hb (normal = 11.4-19.4 micromol/g Hb). The patient's bisphosphoglycerate mutase (BPGM) enzyme activity was also markedly decreased at 0.16 IU/g Hb (normal = 4.13-5.43 IU/g Hb). A red cell enzyme panel revealed a markedly decreased G-6-PD level (0.3 U/g Hb, normal = 8.6-18.6 U/g Hb). His parents and a brother were also available for evaluation. Both parents showed normal 2,3-BPG levels but BPGM activity approximately 50% of normal. Paradoxically, the brother showed normal BPGM activity but a slightly decreased 2,3-BPG level. All family members had markedly decreased G-6-PD activity. DNA sequencing of the BPGM gene showed the propositus to be homozygous for 185 G-->A, Arg 62 Gln in exon 2. Thus, the erythrocytosis in this patient is secondary to low 2,3-BPG levels, due to a deficiency in BPG mutase. This appears due to consanguinity within this family.     

G-6-PD Manchester: A New Variant Associated With Chronic Nonspherocytic Hemolytic Anemia

A variant of glucose-6-phosphate dehydrogenase (G-6-PD) designated G-6-PDManchester, and associated with chronicnonspherocytic hemolytic anemia, wasfound in an English male. The electrophoretic mobility at pH 7.0 of this G-6-PDvariant is the slowest yet described.Substrate specificity is normal but enzymeactivity is markedly inhibited by NADPH,and this is thought to account for the severechronic hemolysis.

Submitted on November 7, 1972 Revised on August 3, 1973 Accepted on August 10, 1973     

G-6-PD Tripler: A Unique Variant Associated with Chronic Hemolytic Disease

A 52-year-old Caucasian was hospitalized for recurring jaundice. Laboratorytests established a compensated hemolytic anemia due to partial erythrocyteG-6-PD deficiency. Biochemical characterization of the affected enzyme uncovered a unique variant: G-6-PD Tripler. Its significant properties includemarked thermal instability, an electrophoretic mobility slower than the normalB variant in all systems studied, and slightly increased affinity for the substrate G-6-P.

Submitted on February 9, 1970 Revised on February 9, 1970 Accepted on February 17, 1970     

G-6-PD deficiency in the Pootai and the So communities in northeast Thailand

The distribution of G-6-PD deficiency amongst two ethnic groups the Pootai and the So in northeast Thailand were studied. The prevalence of G-6-PD deficiency amongst the Pootai males was 9.7% while that amongst the So males was only 2.3%.     

The genetics of glucose-6-phosphate dehydrogenase deficiency

In the past 35 years, G-6-PD and its genetic variants have been a valuable resource for the geneticist and cell biologist. Over 380 putative variants have been described and have served as a paradigm, showing how many ways mutations can affect an enzyme. With the cloning and sequencing of G-6-PD, a new chapter has been opened in our understanding of G-6-PD. Variants that were thought to be different have proven to be identical, and those that were thought to be the same are now seen to be heterogeneous. Importantly, the ability to deduce quickly the amino acid substitution in a G-6-PD variant makes feasible, for the first time, the unraveling of relationships between the structure and function of this enzyme.     

高胆红素血症新生儿血清miR-122水平与肝功能各项指标及葡萄糖-6-磷酸脱氢酶缺乏的相关性研究

目的:探讨高胆红素血症(NHB)新生儿血清miR-122表达与肝功能各项指标和葡萄糖-6-磷酸脱氢酶(G-6-PD)缺乏的相关性。方法:将2020年3月至5月于我院新生儿科足月分娩的新生儿217例,根据临床症状和血清总胆红素(TBil)检测结果分为NHB组(n=144)和非NHB组(n=73),比较两组新生儿肝功能各项指标[谷丙转氨酶(ALT)、谷草转氨酶(AST)、TBil、白蛋白(Alb)、碱性磷酸酶(ALP)、谷氨酰转肽酶(GGT)]以及红细胞G-6-PD酶活性。采用实时荧光定量PCR法检测患儿血清miR-122相对表达量,并分析其与各指标之间的关系。结果:与非NHB组相比,NHB组新生儿血清ALT、AST、GGT、Alb、TBil、CRP水平(Z=-11.858~-2.126,均P<0.05)以及血清miR-122相对表达量(t=4.721,P<0.05)显著升高。根据血清TBil水平,将NHB患儿分为轻度、中度、重度3个亚组;与轻度亚组和中度亚组相比,重度亚组NHB新生儿血清ALT、AST、GGT、TBil、CRP、PCT水平以及血清miR-122相对表达量均升高(H=6.045~63.896,均P<0.05)。NHB患儿血清miR-122相对表达量与ALT、AST、GGT、TBil、PCT水平呈正相关性(r=0.173~0.550,均P<0.05)。22例新生儿G-6-PD缺乏,其血清miR-122相对表达量显著高于G-6-PD正常新生儿(Z=36.831,P<0.05)。结论:在NHB新生儿中,血清miR-122相对表达量普遍升高,这与AST、ALT、AST、GGT、TBil、PCT水平升高、G-6-PD酶缺乏有关,因此加强血清miR-122水平检测有助于更准确地评估NHB患儿肝损伤情况。     

Human mixed cell colonies: unicellular or multicellular origin–analysis by G-6-PD

Marrow and peripheral blood cells from normal women heterozygous (GdB/GdA) at the X-chromosome-linked glucose-6-phosphate dehydrogenase (G-6-PD) locus were cultured at cell concentrations ranging from 2 X 10(4)/ml to 4 X 10(5)/ml to test formally the plating conditions necessary for reliable enumeration of multipotent stem cells (CFU-mix). The culture system was rigorously tested by plating cells obtained after velocity sedimentation and the G-6-PD enzyme type of individual colonies was determined. At cell concentrations less than or equal to 7.5 X 10(4)/ml for marrow and less than or equal to 1 X 25 X 10(5)/ml for peripheral blood, mixed-cell colonies had either type A or type B enzyme, but not both. At higher cell concentrations, significant numbers of colonies showed both enzyme types and therefore arose from more than one cell. These studies demonstrate that enumeration of CFU-mix by in vitro colony assay is accurate only at low cell concentrations. Studies of haematopoietic differentiation relying on in vitro colony assays of multipotent stem cells must be carefully analysed in light of these data.     

Molecular heterogeneity of G6PD deficiency in an Amazonian population and description of four new variants

To characterize the molecular variation in the glucose-6-phosphate dehydrogenase gene (G6PD), 196 asymptomatic and unrelated male G6PD-deficient blood donors from Belém, an Amazonian metropolis (Brazil), were analyzed. This deficiency was detected by horizontal agarose gel electrophoresis and quantitative spectrophotometric assay for enzyme activity. The mutations were searched by PCR/RFLP, SSCP, and direct DNA sequencing. The most frequent G6PD variant was the widespread and common G6PD A- (202G --> A, 376A --> G) observed in 161 subjects (82.1%). Besides this, we found another form of G6PD A- (968T --> C, 376A --> G) in 14 (7.1%) individuals, G6PD Seattle (844G --> C) in 4.6%, G6PD Santamaria (542A --> T, 376A --> G) in 2.5%, and G6PD Tokyo (1246G --> A) in one blood donor. Four novel variants were also identified: G6PD Belém (409C --> T; Pro137His), G6PD Ananindeua (376A --> G, 871G --> A; Asn126Asp, Val291Met), G6PD Crispim with four point mutations (375G --> T, 379G --> T, 383T --> C, and 384C --> T) leading to three amino acid substitutions (Met125Ile, Ala127Ser, and Leu128Pro), and G6PD Amazonia (185C --> A; Pro62His). The reported frequencies do not reflect the real values for blood donors from Belém, since an excess of individuals with "non A-" phenotype was included in this study to enhance the probability to find rare variants. Haplotype analyses were carried out for the less common G6PD variants identified in our study using PCR/RFLP for five polymorphic sites (FokI, PvuII, PstI, BclI, NlaIII). G6PD Crispim and G6PD Amazonia variants presented the most common haplotype found in G6PD B (- - + - -). G6PD Belém presented two haplotypes (- - + + +, - + + + +) and G6PD Ananindeua was found with the + - + - + haplotype. The reported heterogeneity probably is due to the great miscegenation, characteristic of the population of the Amazonian region, besides the apparently common occurrence of recurrent mutations in the G6PD gene.     

Incidence of abnormal haemoglobins and G-6-PD deficiency in school children of Udaipur (Rajasthan), India

Blood samples from 1198 school children (both sexes) of eight endomagous castes of Udaipur (Rajasthan) were investigated for the evidence of abnormal haemoglobins and glucose-6-phosphate dehydrogenase (G-6-PD) deficiency. Abnormal haemoglobins were encountered in 10 children (0.83%); seven Hb-S and three Hb-D. G-6PD deficiency was found in 55 children (4.59%).     

Glucose-6-Phosphate Dehydrogenase Deficiency and Blood Transfusion

Abstract. Seven White American male blood donors with Italian surnames were found to have red cell glucose-6-phosphate dehydrogenase (G-6-PD) deficiency among 1,285 with Greek or Italian surnames screened. Five different genetic variants were found: G-6-PDs Mediterranean (2), 'Athens-like' (2), San Juan, Columbus and 'Canton-like'. Clinical evaluation of 23 patients who received 24 units of G-6-PD-deficient blood (G-6-PD A-) failed to reveal any deleterious effects. Screening of Black donors for G-6-PD deficiency is believed unnecessary; further data are needed before a recommendation can be made concerning screening for non-Black donors.