New stable mutant (Gd(-) variants: G6PD Tashkent and G6PD Nucus. Molecular basis of hereditary enzyme deficiency.

This paper represents studies on the molecular basis of G6PD deficiency in erythrocytes of 4 hemizygote patients. In all cases G6PD deficiency was due to an abnormal kinetic and (or) physico-chemical characteristics of the mutant enzymes. Two of 4 variants were characterized as G6PD EL Fayoum like (unstable, class 2). The other two are new variants: G6PD Tashkent (low Ki by NADPH, class 3) and G6PD Nukus (Km for G6P 127 microM, class 2). For the new mutant Gd(-) stable variants the amount of G6PD in total red cell population found immunologically was similar to the normal level. Stimulation of the pentose phosphate pathway (PPP) of G6PD Nucus erythrocytes insignificantly increased the rate of glucose consumption while in the case of G6PD Tashkent methylene blue raised the rate of PPP to half of the maximal rate of stimulated normal red cells.