title: Congenital methemoglobinaemia due to Hb F-M-Fort Ripley in a preterm newborn.
abstract: Methemoglobinaemia is a rare cause of cyanosis in newborns. Congenital methemoglobinaemias due to M haemoglobin or deficiency of cytochrome b5 reductase are even rarer. We present a case of congenital methemoglobinaemia presenting at birth in a preterm infant. A baby boy born at 29 weeks and 3 days of gestation had persistent central cyanosis immediately after delivery, not attributable to a respiratory or cardiac pathology. Laboratory methemoglobin levels were not diagnostic. Cytochrome b5 reductase levels were normal and a newborn screen was unable to pick up any abnormal variants of fetal haemoglobin. Genetic testing showed a γ globin gene mutation resulting in the M haemoglobin, called Hb F-M-Fort Ripley. The baby had no apparent cyanosis at a corrected gestational age of 42 weeks. Although rare, congenital methaemoglobin aemia should be considered in the differential in a preterm with central cyanosis and investigated with genetic testing for γ globin chain mutations if other laboratory tests are non-conclusive.
authors.affiliation: IWK Health Center, Halifax, Nova Scotia, Canada.
authors.forename: Satvinder
authors.initials: S
authors.lastname: Ghotra
authors.affiliation: IWK Health Center, Halifax, Nova Scotia, Canada.
authors.forename: Krista
authors.initials: K
authors.lastname: Jangaard
authors.affiliation: IWK Health Center, Halifax, Nova Scotia, Canada.
authors.forename: Chantale
authors.initials: C
authors.lastname: Pambrun
authors.affiliation: IWK Health Center, Halifax, Nova Scotia, Canada.
authors.forename: Conrad Vincent
authors.initials: CV
authors.lastname: Fernandez
mesh_terms: D000740:Anemia / Q000175:diagnosis / Q000235:genetics / Q000473:pathology; D003490:Cyanosis / Q000175:diagnosis / Q000209:etiology / Q000235:genetics; D042966:Cytochrome-B(5) Reductase / Q000097:blood; D003937:Diagnosis, Differential; D005319:Fetal Hemoglobin / Q000235:genetics*; D005820:Genetic Testing; D006449:Hemoglobin M / Q000235:genetics*; D006801:Humans; D007231:Infant, Newborn; D007234:Infant, Premature; D008297:Male; D008706:Methemoglobin / Q000235:genetics* / Q000378:metabolism; D008708:Methemoglobinemia / Q000175:diagnosis* / Q000235:genetics / Q000473:pathology; D009154:Mutation; D055545:gamma-Globins / Q000235:genetics
chemical_list: D055545:gamma-Globins; D008706:Methemoglobin; D005319:Fetal Hemoglobin; D006449:Hemoglobin M; C059479:hemoglobin FM Fort Ripley; D042966:Cytochrome-B(5) Reductase