Heterogeneity of hereditary methaemoglobinaemia: a study of 4 Cuban families with NADH-Methaemoglobin reductase deficiency including a new variant (Santiago de Cuba variant).

NADH-methaemoglobin reductase deficiency has been found in 4 Cuban families; 3 subjects carried the mild form of the deficiency while in 2 sibs of the fourth family the deficiency was associated with neurological involvement. The parents in this family were consanguinous and the sibs were shown to be homozygous for a new fast electrophoretic variant. It was named Diaphorase Santiago de Cuba.