Variants of red cell glucose-6-phosphate dehydrogenase among Asiatic Indians

Three major G6PD-deficient polymorphic variants identified among the Mauritian population

We report the results of the first epidemiological study investigating glucose 6-phosphate dehydrogenase (G6PD) deficiency among the heterogenous Mauritian population. Mauritius has a population of approximately 1 million, and of these 66.8% are Indo-Mauritian (of Indian origin), 27.9% are Creoles (of African ancestry) and 2.1% are Sino-Mauritian, predominantly of Chinese origin. Of the 1435 Mauritian males tested, 73 (5.1%) were G6PD deficient. However, the prevalence varied considerably between the two major ethnic groups: 35/1157 (3.0%) for Indo-Mauritians and 37/267 (13.9%) for Creoles. Molecular analysis revealed three major deficient polymorphic variants; G6PD Orissa, G6PD Mediterranean and G6PD A-. G6PD Orissa (nt 131 G-->C; residue 44 Ala-->Gly) was found to be the most common variant among Indo-Mauritians: this deficient variant was recently identified to be highly characteristic of the tribal groups in central India. In Creoles the most common deficient variant was G6PD A- (27/37). These data are consistent with the different ancestral contributions to the present gene pool of the Mauritian population. This study has provided further information as to the precise nature of G6PD deficiency at the molecular level among Indians, about whom previously there was scant information. The data presented suggest that G6PD Orissa is widespread in central and southern states of India. Additionally, the identification and frequency of G6PD-deficient alleles in Mauritius is of public-health importance.

Prevalence and clinical presentation of glucose-6-phosphate dehydrogenase deficiency in Pakistani Pathan and Afghan refugee communities in Pakistan; implications for the use of primaquine in regional malaria control programmes

Glucose-6-phosphate dehydrogenase (G-6-PD) deficiency surveys in Afghan refugees and a local community in the North-West Frontier Province, Pakistan, showed that this trait was most common among Pathan and Uzbak refugees (15.8% and 9.1% respectively). The prevalence among Pakistani Pathans was 7.0%, and that in Tajik and Turkoman refugees was 2.9% and 2.1% respectively. Hospital studies showed that the type of G-6-PD deficiency in Pathans could cause severe haemolytic crises. The potentially fatal side effects of primaquine treatment in the Pathan communities, and the high risk of re-infection, render the anti-relapse treatment policy for Plasmodium vivax obsolete. However, epidemic conditions of P. falciparum malaria may justify the use of primaquine as a gametocidal drug, administered as a single dose, during the transmission season. These findings necessitate revision of the recommendations for the use of primaquine in the area.

Red cell glutathione peroxidase (GPX1) variation in Afro-Jamaican, Asiatic Indian, and Dutch populations. Is the GPX1*2 allele of "Thomas" variant an African marker?

A Cellogel procedure for screening the electrophoretic variants of the human red cell glutathione peroxidase ( GPX1 ) was described. Three hundred and ninety eight Dutch persons living in various parts of The Netherlands, 385 individuals born in various states of India, and 72 Jamaicans of African origin living in Birmingham, UK, were screened for GPX1 variants. The Dutch were monomorphic, while one Afro-Jamaican female and two males and one female of the 116 Punjabis were found to be variants indistinguishable from each other in their pattern of electrophoresis. The clear five banded pattern of the variant indicated that the subunit structure of the human red cell glutathione peroxidase is most probably a tetramer and suggested that the variant is the expression of a heterozygote due to alleles at an autosomal locus. The corresponding phenotype was designated tentatively as GPX1 2-1 and the alleles as GPX1 *1 and GPX1 *2 respectively. The variant 2-1 was found to be identical to the "Thomas" variant described by Beutler and West (1974). Thus so far, in addition to the Afro-Americans and Ashkenazi Jews (Beutler et al. 1974), the Punjabis of the Indian subcontinent (this report) were found to exhibit the GPX1 polymorphism due to the GPX1 *2 allele. The data discussed in this paper (which included unpublished observations on several African and non-African populations) suggest that the GPX1 *2 allele is originally an African variant and hint that the present day Punjabis of Indian subcontinent, like Ashkenazi Jews, are "predominantly of Mediterranean origin with some proportion of African ancestry" ( Mourant et al. 1976).

A new glucose-6-phosphate dehydrogenase variant (G-6-PD Kalyan) found in a Koli family

A new Indian variant of erythrocytic glucose-6-phosphate dehydrogenase (G-6-PD) has been detected in a Koli male subject during population genetic studies. The enzyme variant is characterized by mild enzyme deficiency, slow electrophoretic mobility, low Km for G-6-P, increased utilization of substrate analogues, heat instability and a normal pH optimum curve. From these results this was considered to be a new variant and was designated G-6-PD Kalyan. The family history and routine hematological studies did not reveal any evidence that the G-6-PD Kalyan is associated with any hematological abnormalities or clinical symptoms.

Depression of erythrocyte glucose-6-phosphate dehydrogenase (G6PD) activity in enteric fever

Ninety adult Indian typhoid and paratyphoid fever (enteric fever, EF) patients and 91 controls were tested for glucose-6-phosphate dehydrogenase (G6PD) deficiency using the fluorescent spot test (FST) and the quantitative methaemoglobin reduction test ( QMRT ). There was a threefold higher incidence of G6PD deficiency in North Indian EF patients (10.6%) than in controls (3.6%) (P = 0.15) which may be attributable to the greater morbidity of the G6PD-deficient EF patients; six of nine had haemolytic anaemia. A transient depression of mean erythrocyte G6PD activity was observed in a subgroup of 49 non-deficient EF patients in whom the spectrophotometric G6PD assay was done. It did not appear to be related to reticulocyte count, chloramphenicol therapy, or differences in leucocyte contamination of the haemolysate used for the G6PD assay. If this depression of G6PD activity occurs in deficient patients as well, it may help to explain the haemolysis seen in them during EF. Of the three tests used, the QMRT and the spectrophotometric assay clearly identified G6PD deficiency in males during haemolysis, whereas the FST was unreliable in this situation.

Hemoglobin variants in India

The occurrence of different types of hemoglobin variants in India has been well-documented in urban populations and in certain tribal areas. Beta-thalassaemia and hemoglobins D,E,H,S, and rare variants like Hb Lepore, have been found in varying percentages. There is a higher incidence of Hb E in the Eastern region and of Hb D in certain Northern populations. The association of Hb E with beta thalassaemia G6PD deficiency has been established. The relationship with other environmental factors, like malaria, is not yet clear.

Glucose-6-phosphate dehydrogenase Porbandar: a new slow variant with slightly reduced activity in a South African family of Indian descent

A new variant of the red cell enzyme glucose-6-phosphate dehydrogenase has been detected in a South African male of Indian descent and in several of his relatives. The enzyme variant is characterized by slow electrophoretic mobility, low Michaelis constants for the substrates glucose-6-phosphate and NADP, and increased utilization of the substrate analogues 2-deoxyglucose-6-phosphate and deamino-NADP relative to the normal (B+) enzyme. There is no evidence that the enzyme variant, for which the name "G6PD Porbandar" is suggested, is associated with any hematological abnormality.

The distribution of blood genetic markers in immigrant Chinese populations

The current data on the distribution of blood genetic markers in Chinese populations outside China have been reviewed and summarised. The Chinese were found to exhibit varying degrees of heterogeneity in some of the marker systems, and attempts have been made, where appropriate, to relate this heterogeneity to the diverse backgrounds in China of the populations studied.

Atypical cholinesterase gene E1a: rarity in Negroes and most Orientals

Development of a rapid screening test for atypical cholinesterase in serum enabled large-scale surveys of populations. The frequency of the heterozygous trait among Greeks, Yugoslavs, and East Indians was similar to that among United States Caucasians (2.8 to 3.3 percent). In trait frequency, U.S. Negroes were intermediate (1.05 percent) between Congolese Africans (0.29 percent) and U.S. Whites (3.3 percent). The gene was absent from or very rare in populations originating in East Asia (Taiwanese, Japanese, Filipinos, and Eskimos). Prolonged apnea during anesthesia from administration of succinylcholine caused by homozygosity for this gene, is expected to be extremely rare among populations of Negroes and East Asians.