Table 3 The three approved disease-modifying therapies for spinal muscular atrophy (SMA)

Nusinersen (Spinraza)

Antisense oligonucleotide/alters SMN2 splicing

Fixed dose: 12 mg;

intrathecal injection

Six injections in the first years, then three injections per year;

lifelong use

No age restriction

Stabilizes or improves motor function in SMA patients of all ages, with better outcomes when treated presymptomatically

Transient deafness, fever, urinary tract infection, coagulation abnormalities, headache, dizziness, back pain, vomiting, and post-lumbar puncture syndrome

Onsemnogene abeparvovec (Zolgensma)

Gene therapy/SMN1 gene carried by AAV9 vector

Dose based on body weight: 1.1 × 10¹⁴ vg/kg; intravenous injection

One-time treatment

Under 2 years

Stabilizes or improves motor function in SMA patients of < 2 years, with better outcomes when treated presymptomatically

Vomiting, fever, temporarily elevated ALT/AST, hepatoxicity, decreased platelet count, thrombotic microangiopathy, renal impairment, and elevation of troponin I

Risdiplam (Evrysdi)

Small molecule/alters SMN2 splicing

#Dose based on body weight capped at 5 mg once daily for SMA patients aged ≥ 2 years (≥ 20 kg); oral route

Once daily/lifelong use

No age restriction

Stabilizes or improves motor function in SMA patients of all ages, with better outcomes when treated presymptomatically

Fever, rash, mouth ulcers, headache, loose stool, abdominal pain, joint pain, urinary tract infections, and hypoglycemia