2022 年 39 巻 3 号 p. 298-301
Spinal muscular atrophy (SMA) is an autosomal recessive lower motor neuron degenerative disease. Approximately 90% of patients do not produce normal survival motor neuron (SMN) protein due to deletion or mutation of the SMN1 gene. Instead, the SMN2 gene produces SMN protein, but when transcribed into mRNA, exon7 is skipped by about 90%, and full–length functional SMN protein is produced by only about 10%. Intrathecal nusinersen in 2017 and oral risdiplam in 2021 became available as treatments for adult SMA. The importance of diagnosing SMA with therapeutic agents is increasing. Nusinersen is an antisense oligonucleotide preparation that modifies splicing of SMN2 gene. After the 3–month introduction period, maintenance administration will be performed every 6 months. Since the administration interval is different from overseas, the therapeutic effect overseas does not always match the therapeutic effect in this method. Intramedullary approach may be required under fluoroscopy in patients who have difficulty with normal lumbar puncture due to scoliosis. Risdiplam is also a small molecule compound that modifies splicing SMN2 gene. Adult SMA patients are now able to choose between two treatments. Diagnosis will become more and more important in the future.
