Hemoglobin F-Toms River
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Very rare. Congenital abnormality of the fetal hemoglobin where valine is replaced by methionine in position 67 in the γ chain. All cases reported to date were de novo mutations of the HBG2 gene (11p15.4).
This anomaly results in:
- decreased affinity of HbF for oxygen and therefore a cyanosis without hypoxemia that does not respond well to the administration of oxygen
- moderate anemia.
Cyanosis and anemia improve progressively as the HbF γ chain is replaced by the adult Hb β chain. Healing is complete around 5-6 months of age.
Other neonatal hemoglobinopathies caused by a mutation in the HbF γ chain can lead to congenital methemoglobinemia (see congenital Methemoglobinemia).
These are:
- HFM-Osaka: where histidine is replaced by tyrosine in position 63
- HFM-Fort Ripley: where histidine is replaced by tyrosine in position 92
- HFM-Circleville: where histidine is replaced by leucine in position 63
- HFM-Cincinnatti: where phenylalanine is replaced by serine in position 41
- HFM-Viseuo: where leucine is replaced by methionjine in position 28, altering the configuration of Hb in position 63
Anesthetic implications:
neonatal cyanosis without hypoxemia; transcutaneous paO2 monitoring
References :
- Crawley MA, Mollan TL, Abdulmalik OY, Butler AD et al.
A hemoglobin variant associated with neonatal cyanosis and anemia.
NEJM 2011; 364(19): 1837-43.
Updated: December 2019