Rare. Sporadic or dominant autosomal transmission of a mutation of the HBB gene (11p15.4), where Thr replaces Lys in position 66 of the Hb beta chain. This change results in a decreased affinity of hemoglobin for oxygen with a deviation to the right of the oxyhemoglobin dissociation curve. (p50  = 40 mmHg versus 27 mmHg for normal hemoglobin).

Clinically: moderate cyanosis, and mild anemia due to decreased erythropoietin production (following increased O2 intake to tissues)

Anesthetic implications: 

falsely lowered SpO2; to assess paO2, arterial blood gases or transcutaneous paO2 measurement are required

References :

-        Starkey CR, Davies L, Hoyer JD, Wilson CS, Winter SS. 
Clinical manifestations of Hemoglobin Chico at high altitude.
J Pediatr Hematol Oncol 2006; 28: 760-2

Updated: January 2020