Very rare. Abnormality of hemoglobin due to a mutation of the HBA2 gene (codon 94: GAC > AAC) that decreases the affinity of Hb for oxygen in the same way as HbF. Electrophoresis shows a  migration close to the HbS one, that can lead to a wrong diagnosis of HbS or thalassemia  although these diseases do not result in cyanosis.

Anesthetic implications: 

falsely low SpO2(< 90% at room air) that improves very little in case of O2 supplementation.

References : 

-         Deyell R, Jackson S, Spier S, Poon M-C.
Low oxygen saturation by pulse oximetry may be associated with a low oxygen affinity hemoglobin variant, hemoglobin Titusville.
J Pediatr Hematol Oncol 2006 ; 28 : 100-2

-        Luo H-Y, Irving I, Prior J, Lim E, Eung SH et al.
Hemoglobin Titusville, a low oxygen affinity variant hemoglobin in a family of Northern European background.
Am J Hematol 2004: 77: 384-6

-        Gilbert G, Delhourne M, Donnard M, Chevaleyre S, Ponsonnard S.
Un diagnostic rare de désaturation.
Anesth Réanim 2016; 6 : 410-2

Updated: December 2016