Spinal Muscular Atrophy in India:
Symptoms, Genetic Testing, and the Truth About Gene Therapy Costs
Spinal Muscular Atrophy (SMA) is an inherited neuromuscular disorder that damages the motor neurons in the spinal cord, affecting the ability to sit, walk, swallow, and eventually breathe. The root cause is a faulty or missing SMN1 gene, inherited in an autosomal recessive pattern. A child is affected only if they inherit a non-working copy from both parents.
Humans also carry a nearly identical backup gene, SMN2, which produces the same protein but in smaller amounts. The number of SMN2 copies largely determines severity — more backup copies generally mean a milder course.
The Four Types of SMA
| Type | Onset | Typical Course |
|---|---|---|
| Type 1 (most severe) | Before 6 months | Cannot sit unsupported; historically fatal in infancy without treatment |
| Type 2 | 6–18 months | Can sit but not walk independently |
| Type 3 | After 18 months (childhood) | Can walk initially; may lose the ability over time |
| Type 4 (mildest) | Adulthood | Mild muscle weakness, normal lifespan |
Early signs in infants include a “floppy” body, weak cry, difficulty feeding, and delayed motor milestones. In older children: frequent falls, waddling gait, or trouble climbing stairs.
How Common Is SMA in India, Really?
📊 Carrier frequency in North India: ~1 in 38 (slightly higher than global average of 1 in 40–50).
Because it’s recessive, most carriers never know unless tested. SMA is the second most common fatal autosomal recessive disorder worldwide. In India, high carrier rates combined with consanguineous practices in some communities increase the risk.
There is a diagnostic gap: India does not yet have universal newborn SMA screening, so diagnosis is often delayed — sometimes until a family has already lost one child.
How Genetic Testing Identifies SMA
- Diagnostic testing (symptomatic child): looks for homozygous deletion of exon 7 in SMN1 — confirms SMA with high accuracy.
- Carrier screening (healthy adults, before/during pregnancy): identifies one non-working copy; most SMA cases occur with no family history.
- SMN2 copy number analysis: helps predict severity and guides treatment.
- Prenatal & preconception counselling: when both partners are carriers, genetic counselling walks through the 25% risk per pregnancy.
The Truth About Gene Therapy Costs
There are three major SMA-modifying treatments globally. Below is an honest, no-spin look at the numbers in India.
- 🧬 Zolgensma (onasemnogene abeparvovec) — one-time gene therapy, approved for children under 2.
₹16–18 crore per dose. Imported, highly specialised viral-vector tech. Manufacturer’s global compassionate-access program has closed. - 💉 Spinraza (nusinersen) — spinal fluid injection; loading phase + lifelong maintenance.
~₹87 lakh per injection; lifetime cost can exceed Zolgensma’s one-time price. - 💊 Risdiplam (Evrysdi) — oral liquid, the only one currently approved by India’s CDSCO for standard prescription.
~₹6 lakh per bottle, ongoing dosing based on age/weight.
📌 2025 Delhi High Court ruling
Allowed an Indian generic manufacturer to produce its own version of Risdiplam, potentially bringing costs down dramatically for the estimated ~2 lakh SMA patients in India.
For now, most Indian families facing an SMA diagnosis must choose between crowdfunding, compassionate-access applications, or the oral option.
Why Prevention Matters More Than the Headlines Suggest
Because the vast majority of SMA cases occur in couples with no family history, carrier screening is the only tool to catch this risk in advance. If you’re planning a pregnancy, have a family history of unexplained infant muscle weakness, or simply want clarity, genetic counselling and SMN1 carrier testing are worth an honest conversation with a genetics specialist.
Frequently Asked Questions
🧬 SMA India · 29 July 2026
