[Carrier screening and prenatal diagnosis for Spinal muscular atrophy among 8 182 individuals of reproductive age from Zhangzhou region].

OBJECTIVE

To determine the carrier frequency of Spinal muscular atrophy (SMA) among individuals of reproductive age in Zhangzhou, Fujian Province, and provide prenatal diagnosis for high-risk couples.

METHODS

A total of 8 182 individuals of reproductive age who underwent SMA carrier screening at Zhangzhou Municipal Hospital of Fujian Province between January 2021 and March 2025 were selected as study subjects. Those who underwent detection for the copy number of exons 7/8 of the SMN1 gene by real-time quantitative PCR (RT-qPCR) were enrolled as the RT-qPCR group (n = 7 747), and those who underwent detection for the copy numbers of the SMN1/SMN2 genes and other variations by third-generation sequencing (TGS) were enrolled as the TGS group (n = 435). All subjects had a normal phenotype and no history of giving birth to SMA children or family history of SMA. For high-risk couples who were identified as pathogenic variant carriers by screening, multiplex ligation-dependent probe amplification (MLPA) was used during prenatal diagnosis to clarify the fetal genotype. This study was approved by the Medical Ethics Committee of the hospital (Ethics No.: 2025LWB205).

RESULTS

Among the 8 182 individuals, 177 were detected as carriers of pathogenic SMA variants, which yielded a carrier rate of 1/46 (2.16%). Among these, 168 were detected by RT-qPCR as having heterozygous deletion of the SMN1 gene, with a carrier rate of 2.17% (168/7 747), and the main type was heterozygous deletion of SMN1-exon 7 combined with exon 8 (96.43%, 162/168). In the TGS group, 9 carriers of single copy of SMN1 gene were detected, with a carrier rate of 2.07% (9/435). The copy number of SMN2 gene was mainly 2 (59.77%, 260/435), and no other pathogenic point mutations were detected. No significant difference was found in the carrier rate between the two groups (P = 0.889). Two high-risk couples were identified. By prenatal diagnosis, 1 fetus was diagnosed as carrier, whilst 1 fetus was excluded for SMN1 gene deletion. Both fetuses were delivered at full term without adverse outcome.

CONCLUSION

This study has determined the carrier rate of SMA among individuals of reproductive age in Zhangzhou, which may provide reference for the primary and secondary prevention and control of SMA in the region.