Abstract：
Spinal muscular atrophy (SMA) is an autosomal recessive neuromuscular disorder primarily caused by the deletion or mutation of the survival motor neuron 1 (SMN1) gene. This study assesses the diagnostic potential of long-read sequencing (LRS) in three patients with SMA. For Patient 1, who has a heterozygous SMN1 deletion, LRS unveiled a missense mutation in SMN1 exon 5. In Patient 2, an Alu/Alu-mediated rearrangement covering the SMN1 promoter and exon 1 was identified through a blend of multiplex ligation-dependent probe amplification, LRS, and PCR across the breakpoint. The third patient, born to a consanguineous family, bore four copies of hybrid SMN genes. LRS determined the genomic structures, indicating two distinct hybrids of SMN2 exon 7 and SMN1 exon 8. However, a discrepancy was found between the SMN1/SMN2 ratio interpretations by LRS (0:2) and multiplex ligation-dependent probe amplification (0:4), which suggested a limitation of LRS in SMA diagnosis. In conclusion, this newly adapted long PCR-based third-generation sequencing introduces an additional avenue for SMA diagnosis.
摘要：
脊髓性肌萎缩症（SMA）是一种常染色体隐性遗传性神经肌肉疾病，主要由存活运动神经元1（SMN1）基因的缺失或突变引起。这项研究评估了长读测序（LRS）在三名SMA患者中的诊断潜力。对于具有杂合SMN1缺失的患者1，LRS揭示了SMN1外显子5的错义突变。在患者2中，通过多重连接依赖性探针扩增（MLPA）的混合物鉴定了覆盖SMN1启动子和外显子1的Alu/Alu介导的重排，LRS,和Gap-PCR。第三个病人,出生于一个近亲家庭,携带4个杂种SMN基因拷贝。LRS确定了基因组结构，表明SMN2外显子7-SMN1外显子8的两个不同杂种。然而,通过LRS(0:2)和MLPA(0:4)发现SMN1-SMN2比率解释之间存在差异，提示LRS在SMA诊断中的局限性。总之,这种新调整的基于长PCR的第三代测序为SMA诊断提供了额外的途径.
