Characterization of Glucose-6-Phosphate Dehydrogenase Variants in the Sudan – Including Gd^Khartoum, a Hyperactive Slow Variant

Abstract

Erythrocyte glucose-6-phosphate dehydrogenase (G6PD) was characterized in blood samples of 94 male subjects in Sudan having deficient and non-deficient electrophoretic variants. They comprised 44 Gd^B, 17 Gd^A, 19 Gd^B-, 11 Gd^A- and 3 non-deficient (Gd^Khartoum) variants. Biochemical characteristics including enzyme activity, electrophoretic mobility, K_m for glucose-6-phosphate (G6P) and nicotinamide adenine dinucleotide phosphate (NADP), heat stability and pH optimum of all the common and deficient variants were consistent with the reported characteristics of these variants. The Gd^ĸhartoum variant had 9% mobility in TEB buffer and 100% in phosphate buffer, 120% activity, K_m of 130 ± 49 µm for G6P and 0.8 ± 0.2 µm for NADP, lowered thermostabil-ity and an optimum pH of 7.6. This variant was not inhibited by 15 mM maleic acid, 10 m Miodoacetate and dehydro-iso-androsterone. All other variants were inhibited by dehydro-iso-androsterone but uninhibited by maleic acid and iodoacetate.

Molecular Variants of Red Cell Glucose-6-Phosphate Dehydrogenase Deficiency in Central Java, Indonesia

“…This 348 Socmant ri/Saha/Saha/T ay G6PD Deficiency in Java Table 3. Distribution of G6PD mutations in the G6PD-defïcient Javanese may be similar to GdKharloum, first described in the Sudan and later observed in Saudi Ara bia [25].…”

Biochemical characteristics of glucose-6-phosphate dehydrogenase variants among the Malays of Singapore with report of a new non-deficient (Gd Singapore) and three deficient variants

“…The other characteristics (Kin G6P), utilization of analogues (2dG6P, dAmNADP), heat stability and pH optimum were within normal range while Km for NADP (23 t~M) and ~ utilization for Gal6P were higher (11~) than that in Gd B. Gd singap~ is a new non-deficient variant unreported in the literature. Recently a new hyper-active variant (Gd Kh~rt~ of slow mobility, prevalent in Sudan and Saudi Arabia has been characterized (Saha and Samuel, 1991).…”

“…However, most of the studies have been carried out on G6PD deficient samples because of the ease of screening the test. Population genetics of red cell G6PD in African and Asian populations suggest that the prevalence of non-deficient alleles is not uncommon (Nakatsuji and Miwa, 1979;Samuel et al, 1981;Saha, 1984;Panich, 1986;Saha and Samuel, 1991). As such, probably the earlier studies based on the enzyme deficient samples grossly underestimate the degree of genetic heterogeneity of the Gd locus in man.…”

Prevalence of glucose-6-phosphate dehydrogenase deficiency (G6PDd), CareStart qualitative rapid diagnostic test performance, and genetic variants in two malaria-endemic areas in Sudan

“…Testing with the CareStart POC test provided a higher estimated prevalence, which is consistent with other studies [ 35 – 38 ]. Earlier reports of G6PD in Sudan focused on enzyme isoforms only, but did not provide associated frequencies [ 6 , 39 ]; and a recent study conducted in Northern Sudan reported on polymorphic genetic variants of the enzyme [ 5 ].…”

“…vivax infection. To date, reports originating from Sudan on glucose-6-phosphate dehydrogenase deficiency (G6PDd) are limited [ 4 – 6 ]. The G6PD gene consists of 13 exons and 12 introns, which are located on the long arm of the X-chromosome at gene loci Xq28.…”