Hematological Characteristics of β-Globin Gene Mutation -50 (G>A) (HBB: c.-100G>A) Carriers in Mainland China.

The -50 (G>A) (HBB: c.-100G>A) mutation was first reported as a β-thalassemia (β-thal) allele in a Chinese family. However, the hematological features of carriers with this variant are not available. In this study, we present the hematological data associated with -50 (G>A) to determine its phenotype. During a 4-year period, eight simple heterozygotes and three double heterozygotes for the -50 mutation and α-thalassemia (α-thal) were included. The simple heterozygotes had normal hematological parameters. The double heterozygotes had the hematological findings of simple α-thal heterozygotes. Two subjects with a compound heterozygosity for -50 and β-thal were also found, and both had typical hematological parameters of β-thal trait. Therefore, we present evidence that -50 (G>A) is likely a silent β-thal allele. Compound heterozygotes for -50/β-thal had no phenotype of severe β-thal. This information might be helpful in genetic counseling for couples in thalassemia high-prevalence areas.