First Case of a Compound Heterozygosity for Two Nondeletional α-Thalassemia mutations, Hb Constant Spring and Hb Quong Sze

Abstract

Nondeletional α-thalassemia (α-thal) is the result of point mutations in critical regions of the α-globin genes, affecting mRNA processing, mRNA translation, or α-globin stability. Hb Constant Spring (Hb CS, HBA2: c.427T > C) is the most common nondeletional α-thal that results from a nucleotide substitution at the termination codon of the α2-globin gene. Hb Quong Sze (Hb QS, HBA2: c.377T > C) is another nondeletional α-thal in South China with the missense mutation at codon 125 of the α2-globin gene making this hemoglobin (Hb) variant highly unstable. Although homozygosity for Hb CS (α^CSα/α^CSα) or Hb QS (α^QSα/α^QSα) has been reported, clinical pictures vary from severe hemolysis that developed early in life to only mild anemia, no clinical phenotypic data of compound heterozygosity for Hb CS/Hb QS (α^CSα/α^QSα) has been described. In this report we describe an adult case with such a compound heterozygosity who presented with a mild α-thal.

• α-Thalassemia (α-thal)
• compound heterotozygosity
• Hb Constant Spring (Hb CS)
• Hb Quong Sze (Hb QS)
• nondeletional

Declaration of interest

This study was supported by a grant from Guangzhou Health Bureau (20141A010021), Guangdong, People’s Republic of China. The authors report no conflicts of interest. The authors alone are responsible for the content and writing of this article.