Relevance of Next-Generation Sequencing in the Diagnosis of Thalassemia and Hemoglobinopathies: The Experience of Four Italian Diagnostic Hubs.

Unlabelled: Thalassemias and hemoglobinopathies are among the most common genetic diseases worldwide and have a significant impact on public health. The decreasing cost of next-generation sequencing (NGS) has quickly enabled the development of new assays that allow for the simultaneous analysis of small nucleotide variants (SNVs) and copy number variants (CNVs) as deletions/duplications of α- and β-globin genes.

Background/objectives: This study highlighted the efficacy and rapid identification of all types of mutations in the α- and β-globin genes, including silent variants, using the Devyser Thalassemia NGS kit. Furthermore, we report the frequency of mutations identified in a total population of 2649 individuals recruited from four Italian Medical Genetics Laboratories.

Methods: All samples were first hematologically characterized, and sequence analysis was conducted by using the Devyser Thalassemia NGS kit. All variants were also validated in an independent sample by a conventional molecular test.

Results: A total of 1789 subjects were identified with genetic variants in the globin genes, of which 966 (53.9%) had variations in the β-gene, 480 (26.8%) had variations in the α-gene; and 307 (17.1%) had variations in both α- and β-genes. Variant analysis evidenced a heterogeneous mutation spectrum enriched with variants not usually observed in the Italian population.

Conclusions: This study showed the high effectiveness and the rapid identification of all mutation types in both α- and β-globin genes, including silent variants. It should be emphasized that the NGS approach greatly shortens turnaround reporting times, overcoming the classic diagnostic flowchart which envisages multistep, subsequent, diagnostic approaches, often requiring long resolution times.