Novel α⁰-Thalassemia Deletion Identified in an Indian Infant with Hb H Disease

Abstract

We report the identification of a large deletion of the α-globin gene cluster, which removed both HBA2 and HBA1 and included the region from HBZ to HBQ1 on chromosome 16 (16p13.3). The α⁰-thalassemia (α⁰-thal) deletion was discovered in an Indian family residing in New Zealand. The proband was a 3-month-old female, who presented with a Hb H disease of unknown molecular origin. Routine hematology showed marked hypochromic microcytic anemia, with numerous Hb H inclusion bodies. In the absence of iron deficiency, there was a strong clinical suspicion of α-thal. On initial screening using a multiplex gap polymerase chain reaction (gap-PCR), only the common rightward deletion (–α^3.7) was detected. Investigation of the proband’s mother and father revealed the mother was heterozygous for the –α^3.7 deletion, while none of the seven most common pathogenic α-thal deletions were detected in the father. Multiplex ligation-dependent probe amplification (MLPA) was employed to detect the presence of a novel α⁰-thal deletion in both the proband and her father. For the proband, the α⁰-thal deletion in combination with the –α^3.7 deletion, eliminated three copies of HBA consistent with a clinical diagnosis of Hb H disease.

Keywords:

• α⁰-Thalassemia (α⁰-thal)
• hemoglobin (Hb) H disease
• multiplex ligation-dependent probe amplification (MLPA)
• novel α-globin gene deletion

Acknowledgments

We wish to acknowledge the molecular pathology departments at LabPLUS, Auckland, New Zealand and Canterbury Health Laboratories, Christchurch, New Zealand for undertaking molecular testing. Also Pathlab Waikato, Hamilton, New Zealand for providing technical assistance. This study was conducted with the approval of the subjects and followed the principles of the Declaration of Helsinki.

Disclosure statement

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