Analysis of rare thalassemia genetic variants based on third-generation sequencing

Thalassemia is a group of common hereditary anemias that cause significant morbidity and mortality worldwide. However, precisely diagnosing thalassemia, especially rare thalassemia variants, is still challenging. Long-range PCR and long-molecule sequencing on the PacBio Sequel II platform utilized in this study could cover the entire HBA1, HBA2 and HBB genes, enabling the diagnosis of most of the common and rare types of thalassemia variants. In this study, 100 cases of suspected thalassemia were subjected to traditional thalassemia testing and third-generation sequencing for thalassemia genetic diagnosis. Compared with traditional diagnostic methods, an additional 10 cases of rare clinically significant variants, including 3 cases of structure variants and 7 cases of single nucleotide variations (SNVs) were identified, of which a case with - alpha(3.7) subtype III (- alpha(3.7III)) was first identified and validated in the Chinese population. Other rare variants of 11.1 kb deletions (- 11.1/alpha alpha), triplicate alpha-globin genes (aaa(3.7)/alpha alpha) and rare SNVs have also been thoroughly detected. The results showed that rare thalassemia variants are not rare but have been misdiagnosed by conventional methods. The results further validated third-generation sequencing as a promising method for rare thalassemia genetic testing.

Automated summary

Thalassemia is a common hereditary anemia with significant morbidity and mortality worldwide. Precise diagnosis of thalassemia, especially rare variants, remains challenging. This study utilized long-range PCR and long-molecule sequencing to diagnose common and rare types of thalassemia variants. Compared with traditional methods, the study identified rare clinically significant variants that were misdiagnosed previously. The results validated third-generation sequencing as a promising method for rare thalassemia genetic testing.