A More Universal Approach to Comprehensive Analysis of Thalassemia Alleles (CATSA)

The aim of the study was to assess the clinical utility of a third-generation sequencing (TGS) approach termed comprehensive analysis of thalassemia alleles (CATSA) for identifying both α and β thalassemia genetic carrier status. Prospective blood samples (n = 1759) with abnormal hemoglobin parameters were screened for pathogenic thalassemia variants by CATSA on the PacBio TGS platform. In 1159 individuals, a total of 1317 pathogenic thalassemia variants were identified and confirmed by independent PCR-based tests. Of the total thalassemia variants detected, the α-variant --SEA (35.4%) and β-variant c.126_129delCTTT (15%) were the most common. CATSA was also able to detect three types of rare HBA structural variants as well as five rare HBA2, three HBA1, and 10 HBB single-nucleotide variations/insertions and deletions. Compared with standard thalassemia variant PCR panel testing, CATSA identified all panel variants present, with no false-negative results. Carrier assignment was improved through identification of rare variants missed by the panel test. On the basis of allelic coverage, reliability, and accuracy, TGS with long-range PCR presents a comprehensive approach with the potential to provide a universal solution for thalassemia genetic carrier screening. It is proposed that CATSA has immediate clinical utility as an effective carrier screening approach for at-risk couples.