congenital methemoglobinemia(redirected from primary methemoglobinemia)
1. methemoglobinemia due to formation of any one of a group of abnormal α chain [MIM*141800] or β chain [MIM*141900] hemoglobins collectively known as hemoglobin 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;
2. methemoglobinemia due to deficiency of cytochrome b5 reductase [MIM*250790] or methemoglobin reductase [MIM*250700], the enzyme responsible for reduction of intraerythrocyte methemoglobin; cyanosis is improved by ascorbic acid or methylene blue; autosomal recessive inheritance;
Elevated levels of methemoglobin in the blood, resulting from one of several hereditary deficiencies of methemoglobin reductase. Affected persons may appear mildly cyanotic but are rarely symptomatic.
See also: methemoglobinemia
con·gen·i·tal met·he·mo·glob·i·ne·mi·a(kŏn-jeni-tăl met-hēmō-glō-bi-nēmē-ă)
1. Methemoglobinemia due to formation of any one of a group of abnormal α chain or β chain hemoglobins collectively known as hemoglobin M.
2. Methemoglobinemia due to deficiency of cytochrome b5 reductase or methemoglobin reductase.