A second observation of the fetal methemoglobin variant Hb F-M-Fort Ripley or alpha 2G gamma 2(92)(F8)His----Tyr.
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.
Molchanova
T P
TP
Laboratory of Protein Chemistry, Medical College of Georgia, Augusta 30912-2100.
Wilson
J B
JB
Gu
L H
LH
Hain
R D
RD
Chang
L S
LS
Poon
A O
AO
Huisman
T H
TH
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
D005319:Fetal Hemoglobin; D006449:Hemoglobin M; C059479:hemoglobin FM Fort Ripley