Hematological and molecular characteristics of a novel α-globin variant Hb Liangqing (HBA2:c.224A>G)

To report the hematological and molecular characteristics of a novel α-globin variant found among Chinese families.

This study was done on two unrelated families (F1 and F2). Hematological results were obtained by an automated blood cell analyzer. Hemoglobin (Hb) fraction analysis was carried out using capillary electrophoresis (CE) and high-performance liquid chromatography (HPLC). Gap-PCR and reverse dot blot (RDB) methods were used to detect the common α-thalassemia mutations in the Chinese population. The Hb variants were defined by Sanger sequencing.

Hb fraction analysis of F2 cord blood using HPLC showed an abnormal peak (3.5%) of the S-window, but CE presented a 12.2% abnormal peak at zone 5(S). Similar results of CE were observed from the F1 twin's cord blood. Compared with newborns, Hb analysis of F2 father using HPLC demonstrated an abnormal peak (16.9%) of S-window and an unknown peak (0.5%) at a retention time of 4.60 min, respectively. In contrast, CE revealed a high Hb F peak at zone 7 and an unknown peak at zone 1. There was no abnormality detected with Gap-PCR and RDB in these patients. However, Sanger sequencing confirmed the presence of a new heterozygous mutation (GAC>GGC) at codon 74 of the HBA2 gene (HBA2:c.224A>G), resulting in a novel Hb variant. We named it Hb Liangqing for the birthplace of the proband.

This is the first report of Hb Liangqing detected by HPLC and CE. The normal hematological phenotype suggests that it may be a benign Hb variant.