congenital methaemoglobinaemiamedical dictionary

Methaemoglobinaemia due to formation of any one of a group of abnormal a chain or b chain haemoglobins collectively known as haemoglobin M. Slate-gray cyanosis occurs in early infancy, without pulmonary or cardiac disease, and is resistant to ascorbic acid or methylene blue therapy; autosomal dominant inheritance, methaemoglobinaemia due to deficiency of cytochrome b5 reductaseor methaemoglobin reductase, the enzyme responsible for reduction of intraerythrocyte methaemoglobin; cyanosis is improved by ascorbic acid or methylene blue; autosomal recessive inheritance, one case of methaemoglobinaemia has been reported that apparently is due to a deficiency of cytochrome b5.

Synonyms: hereditary methaemoglobinaemia, hereditary methaemoglobinaemic cyanosis, primary methaemoglobinaemia.

American spelling: congenital methemoglobinemia

(05 Mar 2000)