title: A second observation of the fetal methemoglobin variant Hb F-M-Fort Ripley or alpha 2G gamma 2(92)(F8)His----Tyr.
abstract: We have identified a second baby with the fetal methemoglobin F-M-Fort Ripley. It was observed in a Caucasian infant from Canada; at least eleven additional members of that family were known to have had a neonatal cyanosis similar to that seen in the propositus and in a previously described baby (2). Sequencing of amplified DNA that included (part of) the G gamma gene greatly facilitated the characterization. The G gamma X chain was readily isolated by reversed phase high performance liquid chromatography; its quantity was approximately 12.5% of total gamma. Interestingly, the baby also carried the A gamma T mutation on one chromosome, either in cis or in trans to the G gamma X mutation. Hb F-M-Fort Ripley could be isolated in reasonably pure form by DEAE-cellulose chromatography. The isolated Hb FX was unstable, had spectral changes characteristic for the M-hemoglobins, while its methemoglobin derivative reacted rapidly with cyanide. Oxygen affinity data could not be obtained. It is suggested that the formation of a rather large amount (approximately 25%) of mixed hybrids (alpha 2G gamma X.gamma) with low oxygen affinity is the main cause for the occurrence of the neonatal cyanosis.
authors.affiliation: Laboratory of Protein Chemistry, Medical College of Georgia, Augusta 30912-2100.
authors.forename: T P
authors.initials: TP
authors.lastname: Molchanova
authors.forename: J B
authors.initials: JB
authors.lastname: Wilson
authors.forename: L H
authors.initials: LH
authors.lastname: Gu
authors.forename: R D
authors.initials: RD
authors.lastname: Hain
authors.forename: L S
authors.initials: LS
authors.lastname: Chang
authors.forename: A O
authors.initials: AO
authors.lastname: Poon
authors.forename: T H
authors.initials: TH
authors.lastname: Huisman
mesh_terms: D001483:Base Sequence; D002170:Canada; D003490:Cyanosis / Q000151:congenital / Q000235:genetics; D005312:Fetal Blood / Q000737:chemistry*; D005319:Fetal Hemoglobin / Q000737:chemistry / Q000235:genetics*; D006449:Hemoglobin M / Q000737:chemistry / Q000235:genetics*; D006801:Humans; D007231:Infant, Newborn; D008969:Molecular Sequence Data; D013053:Spectrophotometry
chemical_list: D005319:Fetal Hemoglobin; D006449:Hemoglobin M; C059479:hemoglobin FM Fort Ripley