The Effect of Single Nucleotide Polymorphisms on Clinical Phenotypes of Sabahan Transfusion-Dependent β-Thalassemia Patients with Homozygous Filipino β0-Deletion

Sabah has the highest prevalence of β-thalassemia in Malaysia, with the Filipino β0-deletion as the predominant mutation. Patients with the homozygous Filipino β0-deletion exhibit phenotypic heterogeneity due to various genetic modifiers, yet the effects of these modifiers on the clinical phenotype remain poorly understood. This study investigated the effects of the coinheritance of α-thalassemia, XmnI-Gγ rs7482144, BCL11A rs766432, and 5'HS4 rs16912979 polymorphisms on the clinical phenotype of homozygous Filipino β0-deletion patients in Sabah. Molecular analyses were performed on 124 homozygous Filipino β0-deletion patients using gap-PCR, PCR-RFLP, multiplex PCR, ARMS-PCR, gel electrophoresis, and DNA sequencing. Data showed that the coinheritance of the -α3.7 deletion significantly affected the clinical phenotypes of homozygous Filipino β0-deletion patients (p