A New Glucose 6‐Phosphate Dehydrogenase Variant (G‐6‐PD Verona) in a Patient with Myelodysplastic Syndrome

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Abstract
A 67‐year‐old woman investigated because of ‘myelodysplastic syndrome’ was found to have a 4‐fold increase in G‐6‐PD activity in her erythrocytes. The enzyme was partially purified and characterized. On grounds of (a) reduced electrophoretic mobility, (b) abnormal cathodic band(s) in isoelectrofucusing, (c) increased Michaelis constant for glucose 6‐phosphate, (d) abnormal thermostability, and (e) abnormal interaction with the ligand NADPH, we conclude that this is a new structural variant which we designate G‐6‐PD Verona. G‐6‐PD Verona was the sole apparent source of G‐6‐PD activity in the patient's erythrocytes; by contrast, the patient's fibroblasts had only normal G‐6‐PH (type B). The patient's haematological course terminated into acute myeloid leukaemia. We believe G‐6‐PD Verona was the result of a somatic mutation in an X‐chromosome which took place in a haemopoietic cell clone which subsequently underwent neoplastic transformation.