Targeted high-throughput sequencing technique for the molecular diagnosis of primary immunodeficiency disorders

The aim of this study was to investigate the usefulness of targeted high-throughput sequencing (HTS) for the molecular diagnosis of primary immunodeficiency diseases (PID). A total of 56 clinically diagnosed or suspected PID patients were divided into 4 groups according to the International Union of Immunological Societies Expert Committee for Primary Immunodeficiency 2015 and their chief clinical presentations. Patients and their biological family members were examined by targeted HTS, which sequenced the exons and ±10 bp flanking introns of 171 PID-related genes panel. All significant variants were confirmed by PCR-Sanger sequencing. Pathogenicity of the variants was evaluated by using bioinformatics. A total of 117 variants in 73 genes were found in 56 patients. Accurate molecular diagnosis of PID was made in 13 (23.2%) patients, and 12 novel mutations were detected in these patients. Twenty-seven patients carried heterozygous variants that are probably pathogenic in ≥2 genes; 16 patients had only 1 missense variant, or had several variants but not >1 variant was deleterious as evaluated by bioinformatics. The meaning of the targeted HTS results of these patients remains to be studied. Targeted HTS can make a precise molecular diagnosis of PID and detect more novel pathogenic mutations. More and more variations with ambiguous significance are discovered and explanation of these variations is a challenge to the clinicians.