MOLECULAR CHARACTERIZATION OF THE GLUCOSE-6-PHOSPHATE-DEHYDROGENASE (G6PD) FERRARA-II VARIANT

During the last ten years, molecular biological techniques such as clo ning and sequencing and, more recently, polymerase chain reaction (PCR ) amplification have led to the identification of the molecular defect s responsible for more than fifty glucose-6-phosphate dehydrogenase (G 6PD) variants. In this paper, we report the identification of the mole cular abnormality underlying the G6PD Ferrara II variant, present in t he Po delta area of Northern Italy. Biochemical characterisation shows an enzymatic activity of about 15% of normal (WHO class III), slow el ectrophoretic mobility, low Km for G6P, high percentage substrate anal ogue utilisation and a biphasic pH optimum curve. After PCR amplificat ion, non-radioisotopic single-strand conformation polymorphism analysi s carried out for the entire coding region has revealed a mobility shi ft in exon 8. Nucleotide sequencing has demonstrated a missense 844 G> C mutation, causing an Asp>His amino-acid replacement, known as being responsible for G6PD Seattle, G6PD Modena and G6PD Lodi.