Glucose-6-phosphate dehydrogenase (G-6-PD) mutations in Mexico: four new G-6-PD variants

Screening for mutations at the G-6-PD gene by PCR-SSCP combined with restriction enzyme analysis and DNA sequencing was performed in nine G-6-PD deficient individuals with negative results for the presence of the most frequent G-6-PD mutations previously observed in Mexican population. The variants G-6-PD Valladolid(406T), G-6-PD Durham(713G), and G-6-PD Viangchan(871A) and four new G-6-PD mutant alleles were identified. The new mutations are located at cDNA nt 376 A --> T (126 Asn --> Tyr), nt 770 G --> T (257 Arg --> Leu), nt 1094 G --> A (365 Arg --> His), and nt 1285 A --> G (429 Lys --> Glu) and they were named G-6-PD San Luis Potosi, G-6-PD Zacatecas, G-6-PD Veracruz, and G-6-PD Yucatán, respectively. To date, a total of 18 different G-6-PD variants have been observed in Mexico and several of them are common in Africa, South Europe, and Southeast Asia.     

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 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%.     

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.     

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.     

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.     

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。     

Activity of divicine in Plasmodium vinckei-infected mice has implications for treatment of favism and epidemiology of G-6-PD deficiency

S ummary. Intravenous injection of divicine into mice infected with Plasmodium vinckei rapidly killed the parasites and caused haemolysis. Degenerating parasites were observed frequently inside intact circulating erythrocytes, implying that parasite death was not a passive consequence of haemolysis. Both parasite death and haemolysis were prevented by the iron chelator desferrioxamine. In vitro , divicine caused the accumulation of malonyldialdehyde and the depletion of reduced glutathione in normal mouse erythrocytes. Desferrioxamine inhibited the former event, but not the latter. These observations support the hypothesis advanced by Huheey & Martin (Experientia , 31 , 1145, 1975) to explain the patchy geographical distribution of glucose-6-phosphate dehydrogenase deficiency in historic malarial areas and also suggest that desferrioxamine, a drug already in clinical use, is a potential treatment for favism and other examples of oxidative haemolysis.     

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.     

Thalassaemia,abnormal haemoglobins and iron deficiency in a British Asian population

Summary We have studied the prevalence of β-haemoglobinopathies, α-thalassaemia and iron deficiency in 1256 subjects of mixed British Asian origin (Pakistani, Punjabi, Bengali, Gujarati and other) in East London. We found that 16.3% of males, 32.6% of non-pregnant females and 24% of pregnant females (27.5% overall) had an MCH of < 27 pg and therefore required further investigation to exclude β-thalassaemia. Overall, 4.5% of subjects carried a β-haemoglobinopathy gene and gene frequencies were: β-thalassaemia, 0.014; Hb D, 0.004; Hb E, 0.003; Hb S, 0.001. Alpha thalassaemia trait was found in at least 5.3% of subjects, and although the exact prevalence could not be determined, evidence was obtained using an α-globin gene probe that only half the cases were due to deletional α-thalassaemia-2, the rest being presumptive non-deletional forms. The overall prevalence of iron deficiency of all grades, as assessed by blood counts and plasma ferritin, was 41.9%, and was highest in pregnant women.     

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.