A Rare Alpha-Globin Mutation: Detailed Analysis of the Hb Rogliano Variant (α1 Cod 108 Thr→Asn)

Full abstract

Read the full abstract

α-Thalassemia is an autosomal recessive disorder characterized by reduced synthesis of α-globin chains, most commonly due to deletions within the α-globin gene cluster. Non-deletional variants are less common and contribute to the molecular heterogeneity of the disease. Advances in long-read sequencing have improved the analysis of complex genomic regions, including highly homologous genes such as HBA1 and HBA2. Targeted long-range PCR amplification of the HBA1 and HBA2 genes was followed by long-read sequencing on the PromethION 24 platform (Oxford Nanopore Technologies). Subsequently, the sequencing data were analyzed and visualized using the Integrative Genomics Viewer (IGV). Long-read sequencing achieved an average depth of >390x across all target regions, enabling reliable variant detection. This analysis identified five variants in the HBA1 and HBA2 genes, namely HBA1:c.326C > A (p.Thr108Asn; Hb Rogliano), HBA1:c.-41C > G, HBA2:c0.300 + 55T > G, HBA2:c0.301-24delinsCTCGGCCC, and HBA2:c.-41C > G. Based on ClinVar classification, HBA1:c.326C > A (p.Thr108Asn) was categorized as likely pathogenic, while the remaining variants were classified as benign or likely benign. To our knowledge, this is the first report of Hb Rogliano in Indonesia and highlights the utility of long-read sequencing for the molecular characterization of rare α-globin variants.