Congenital methemoglobinaemia due to Hb F-M-Fort Ripley in a preterm newborn

• Published in: BMJ case reports Vol. 2016; p. bcr2016214381
• Main Authors: Ghotra, Satvinder, Jangaard, Krista, Pambrun, Chantale, Fernandez, Conrad Vincent
• Format: Journal Article
• Language: English
• Published: England BMJ Publishing Group LTD 11.03.2016; BMJ Publishing Group
• Series: Case Report
• Subjects: Anemia - diagnosis; Anemia - genetics; Anemia - pathology; Chromatography; Congenital diseases; Cyanosis; Cyanosis - diagnosis; Cyanosis - etiology; Cyanosis - genetics; Cytochrome; Cytochrome-B Reductase - blood; Diagnosis, Differential; Enzymes; Fetal Hemoglobin - genetics; gamma-Globins - genetics; Genetic Testing; Gestational age; Heart rate; Hemoglobin M - genetics; Humans; Infant, Newborn; Infant, Premature; Male; Medical screening; Methemoglobin - genetics; Methemoglobin - metabolism; Methemoglobinemia - diagnosis; Methemoglobinemia - genetics; Methemoglobinemia - pathology; Mutation; Neonate; Premature babies; Premature birth; Pulse oximetry; Rare Disease; Respiratory distress syndrome; USA/Canada; Ventilators; White
• ISSN: 1757-790X; 1757-790X
• DOI: 10.1136/bcr-2016-214381

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.