A RARE CAUSE OF CYANOSIS: HEMOGLOBIN KANSAS

Abstract

Objective: Hemoglobin Kansas is a variant of hemoglobin with low oxygen affinity and decreased heme-heme interaction. Patients with this variant may have asymptomatic cyanosis and polycythemia. We herein report a Hb Kansas case from Elazığ/Turkey. Case report: A 25-year-old male patient was consulted from the intensive care unit because of low oxygen saturation and peripheral cyanosis. Primary cardiac and pulmonary diseases were excluded in the tests performed before the hematology evaluation. His SpO2 was 40% in room air. Complete blood count was unremarkable except mild polycythemia (Hemoglobin (Hb), 16.9 g/dL; hematocrit, 47.6%; mean red blood cell volume, 94.4 fL; white blood cell count, 9600/mm3, and platelet count 207 × 109/L). Methodology: There was no evidence of hemolysis. An arterial blood gas analysis (under 8 L/min oxygen) showed that the arterial partial pressure of oxygen (PaO2) was 99.1 mmHg and the SaO2 was 61.4%. Both carboxyhemoglobin and methemoglobin levels were in normal range. Hb electrophoresis revealed an abnormal band between HbA and HBA2 in close proximity to the location of HbA (Figure A). Beta globin gene analysis was performed to determine the variant. Results: The HBB gene sequence analysis revealed a c.308A>C missense change resulting in substitution from asparagine to threonine at codon 103 (Hb Kansas). His daughter and father had the same clinic. Conclusion: Hb variants with low oxygen affinity could be considered in patients with unexplained cyanosis if there is dissociation between PaO2 and SaO2. Such patients do not require any special treatment and have a good prognosis. Considering the diagnosis will help prevent unnecessary investigations and treatments.