Clinical significance of Spinal Muscular Atrophy carrier detection in Guangdong Province, China: Insights from quantitative polymerase chain reaction and multiplex ligation-dependent probe amplification analysis

This study aimed to identify carriers of Spinal Muscular Atrophy (SMA) among 10,630 pregnant women in Guangdong Province and provide prenatal diagnoses for high-risk fetuses from carrier couples. The goal was to prevent the birth of children affected by SMA. We evaluated the effectiveness of quantitative PCR (qPCR) and multiplex ligation-dependent probe amplification (MLPA) in detecting deletions in the SMN1 gene, with MLPA as the reference standard. Fluorescent qPCR was used for initial SMA carrier screening, followed by confirmatory testing with MLPA for all detected carriers. Of the 10,630 women screened, 219 were identified as carriers (2.06 % detection rate). This included 17 cases of heterozygous deletion of exon 7 (E7), 145 cases with deletions of both E7 and exon 8 (E8), and 57 cases of E8 deletion alone. The carrier rate for E7 heterozygous deletion was established at 1.5 %. Prenatal diagnosis for seven carrier couples revealed five fetuses as carriers and one affected by SMA. The diagnostic concordance between qPCR and MLPA was 100 %. The combined use of qPCR and MLPA is vital in identifying SMA carriers, allowing for early diagnosis and informed reproductive decisions. The high sensitivity and specificity of qPCR, matching MLPA, demonstrate its value in clinical settings for SMA screening and prenatal diagnosis. Our findings emphasize the critical importance of selecting precise diagnostic methods to enhance clinical outcomes in genetic screening programs. •Screening 10,630 pregnant women in Guangdong revealed a 1.5 % carrier rate for SMN1 exon 7 deletions.•Fluorescent quantitative PCR (qPCR) was highly consistent with MLPA for detecting SMN1 gene deletions.•The total copy number of SMN1 exon 8 and SMN2 exon 8 generally equals that of exon 7.•Differences in exon 7 and exon 8 copy numbers may indicate the presence of micro-deletions.