Clinical Practice of Single‐Molecule Real‐Time Sequencing in the Diagnosis of Spinal Muscular Atrophy

ABSTRACT Objectives To investigate the distribution proportions of the SMN1 gene in spinal muscular atrophy (SMA) using single‐molecule real‐time sequencing (SMRT), thereby providing supplementary evidence for SMA genotyping. Methods A retrospective analysis was conducted on 771 subjects who underwent both real‐time quantitative PCR and SMRT sequencing tests, followed by statistical analysis. Results Among the 771 enrolled individuals, the male‐to‐female ratio was 2:3, with a median age of 31 years. The detection results obtained from real‐time quantitative PCR and SMRT sequencing were consistent. Using SMRT sequencing, the proportions of samples with SMN1 copy numbers 1, 2, 3, and 4 were 2.33% (18/771), 91.18% (703/771), 6.36% (49/771), and 0.13% (1/771), respectively. For SMN2 , the proportions with 0, 1, 2, 3, and 4 copies were 6.10% (47/771), 33.07% (255/771), 57.59% (444/771), 2.98% (23/771), and 0.26% (2/771), respectively. The carrier frequency of SMN1 deletions was 2.33% (18/771). Additionally, we analyzed four SMA patients using SMRT sequencing. The results demonstrate that this technology accurately detects SMN1 and SMN2 copy numbers, providing essential information for patient diagnosis and clinical management. Conclusion With results fully concordant with qPCR, SMRT sequencing enables accurate detection of SMN1 and SMN2 copy numbers, providing robust technical support for population‐based prevention, genetic counseling, and clinical management of SMA.