Biochemical and molecular characterization of a new sporadic glucose-6-phosphate dehydrogenase variant described in Italy : G6PD Modena

A new glucose-6-phosphate dehydrogenase variant detected in an Italian man from the Po delta is described and designated as G6PD Modena. Biochemical characterization of the variant enzyme revealed an activity 21% of normal, a slow electrophoretic mobility, increased K(m) value for NADP, decreased K(m) value for G6P and a complete absence of NADPH inhibition, which could account for the apparently nonhaemolytic feature of this variant. The cloning and sequencing of the G6PD Modena allele showed a G → C transition at nucleotide 844 in exon VIII causing a Asp → His amino acid substitution. On the basis of biochemical characterization, G6PD Modena is classified as a genuine variant but it has the same mutation as G6PD Seattle-like.