Characterization of a novel mutation in the NADH-cytochrome b5 reductase gene responsible for rare hereditary methaemoglobinaemia type I

摘要

Recessive congenital methaemoglobinaemia (RCM) is a very rare recessive genetic disorder (OMIM 250800) caused by a deficiency of NADH-cytochrome b5 reduc-tase (cb5r). Two clinical forms of methaemoglobinaemia have been described [1]. In RCM type I, the cb5r deficiency is limited to erythrocytes, and cyanosis is the only clinical symptom. In RCM type II, cyanosis is associated with severe neurological impairment, because the cb5r deficiency is generalized to all tissues [2]. In general, mutations resulting in the synthesis of unstable cb5r lead to type I methaemoglobinaemia, while mutations associated with severe loss of enzyme activity are often linked to RCM type II. Until now, >40 mutations in unrelated patients from different populations have been described [3].