[MIM 142 250]

Very rare. Sporadic or dominant autosomal transmission of a mutation of the HBG2 gene (11p15.4), where Asn is replaced by Thr in position 308 of the HbF gamma chain. This change results in a decreased affinity of hemoglobin for oxygen with a deviation to the right of the oxyhemoglobin dissociation curve (p50 at about 40-45 mmHg).

This leads to neonatal cyanosis (without any cardiac or respiratory causes), partly responding to oxygen therapy. The cyanosis decreases and disappears progressively as HbF is replaced by HbA.

Anesthetic implications:

keep that possibility in mind in case of unexplained neonatal cyanosis, not responding to oxygenotherapy: arterial blood gases ! Transcutaneous paO2 monitoring.

References : 

-        Lozar-Krivec J, Stepic M, Hovnik T, Krsnik M, Parao-Pajan D.
Neonatal cyanosis due to hemoglobin variant: HB F Sarajevo.
J Pediatr Hematol Oncol 2016; 38: e 267-70

Updated: January 2020