Molecular characterisation of the glucose-6-phosphate dehydrogenase (G6PD) Ferrara II variant

During the last ten years, molecular biological techniques such as cloning and sequencing and, more recently, polymerase chain reaction (PCR) amplification have led to the identification of the molecular defects responsible for more than fifty glucose-6-phosphate dehydrogenase (G6PD) variants. In this paper, we report the identification of the molecular abnormality underlying the G6PD Ferrara II variant, present in the Po delta area of Northern Italy. Biochemical characterisation shows an enzymatic activity of about 15% of normal (WHO class III), slow electrophoretic mobility, low Km for G6P, high percentage substrate analogue utilisation and a biphasic pH optimum curve. After PCR amplification, non-radioisotopic single-strand conformation polymorphism analysis carried out for the entire coding region has revealed a mobility shift 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.