Haemoglobin M -associated with haemolysis

Haemoglobin M   (Hb M) is one of several abnormal haemoglobins associated with methaemoglobinemia. Methaemoglobinemia arises in the blood from the production of non-functional haemoglobin containing oxidised iron (Fe3+). This results in reduced oxygen supply to the tissues and manifests as cyanosis. Under abnormal conditions, large amounts of methaemoglobin can be produced. Hb Ms are inherited as a autosomal dominant trait that cause cyanosis in infancy but usually few other symptoms. Occasionally they may be associated with haemolytic anaemia. There is no available treatment. Methaemoglobinemia can also be found as an hereditary condition in congenital methaemoglobin reductase deficiency or may be acquired by exposure to a chemical toxic or drug.