A Japanese Family with the Unstable Hb Sydney (HBB: c.203T>C) Variant and Persistent Low Hemoglobin Oxygen Saturation

Abstract

Patients with unstable hemoglobin (Hb), caused by a qualitative abnormality in α- and β-globin genes, are often asymptomatic or mildly symptomatic. It is often difficult to diagnose unstable Hb patients with only mild hemolysis or low oxygen saturation. We herein report a case of a family with an unstable Hb, specifically, Hb Sydney (HBB: c.203T>C), an abnormal β-globin chain. A 5-year-old boy was referred to our hospital for low percutaneous oxygen saturation (SpO₂) in the setting of bronchitis. During hospitalization, low SpO₂ persisted despite the improvement in respiratory distress symptoms. As he had mild hemolysis and splenomegaly, his disease was diagnosed to carry Hb Sydney based on gene analysis. His mother and brother also carried Hb Sydney. In this case, bronchial asthma had been treated, but unstable Hb was not assessed. Low SpO₂ may be tolerated and overlooked in cases of asthma and it took time to diagnose this patient. The present case suggests that unstable Hb should be considered in patients with bronchial asthma and prolonged low SpO₂.

Keywords:

• Hb Sydney
• hemoglobin (Hb) variant
• oxygen saturation
• unstable Hb

Acknowledgments

We wish to thank the medical editors from the Division of Education for Clinical Research at the National Center for Child Health and Development, Tokyo, Japan, for editing this manuscript.

Disclosure statement

The authors report no conflicts of interest. The authors alone are responsible for the content and writing of this article.