Note for the team: Add a list of hospitals and laboratories in India that offer SMA genetic testing (MLPA), with approximate costs, and current newborn-screening status in India.
Key points
- Watch for floppiness, weak head control, and delays in rolling, sitting, standing or walking.
- A blood test for the SMN1 gene (usually MLPA) confirms about 95% of cases.
- Treatment works best when started early — if you suspect SMA, ask for testing without delay.
Early signs of SMA
A doctor may suspect SMA when a baby or child is noticeably weak, or is late in reaching developmental milestones. Signs to look out for:
- A “floppy” baby with weak arms and legs
- Difficulty holding up the head
- Late rolling over, sitting, standing or walking — or losing skills they had
- Weak cry or cough, breathing that looks like it uses the tummy more than the chest
- Difficulty feeding or swallowing
- Fine trembling of the fingers or tongue
- In older children and adults: frequent falls, difficulty climbing stairs or getting up from the floor
These signs can have other causes too, so further examination and testing are needed.
How SMA is diagnosed
SMA is usually diagnosed in one of three ways:
- Genetic testing after symptoms appear — the most common route in India today.
- Newborn screening, where it is available.
- Prenatal testing during pregnancy.
If a doctor suspects SMA they may order a genetic test directly, or refer the child to a paediatric neurologist, who will examine them and then order the test.
The genetic test
A simple blood test looks for the missing or faulty SMN1 gene. It identifies about 95% of SMA cases; the remaining 5% are caused by rarer mutations and need further testing. The test usually also reports the number of SMN2 copies, which helps doctors plan treatment.
Ask for a copy of the full genetic report — you will need it for treatment access programmes and to register with us.
Newborn screening
In some countries, every newborn’s heel-prick blood sample is screened for SMA, so treatment can begin before symptoms appear — when research suggests it works best. A positive screening result always needs a follow-up test to confirm the diagnosis.
Newborn screening for SMA is not yet routine across India. If you have a family history of SMA, talk to your doctor about testing your baby soon after birth.
Prenatal testing
Prenatal testing can show whether a baby has inherited SMA. Families who know they are at risk may choose it after discussion with their doctor. Two tests are used:
- Chorionic villus sampling (CVS) — as early as the 10th week of pregnancy. A small sample of the placenta is tested. Associated with a risk of miscarriage of up to about 1 in 100.
- Amniocentesis — after the 14th week of pregnancy. A fine needle takes a small sample of the fluid around the baby. Associated with a risk of miscarriage of up to about 1 in 200.
Carrier testing
About 1 in 50 people is a carrier of SMA. A blood test can show whether you are one. It is recommended for relatives of anyone with SMA and for couples planning a pregnancy. See Genetics & inheritance.
After a diagnosis
A diagnosis of SMA is life-changing, and it is normal to feel overwhelmed. You do not have to work it all out alone. Start with our guide for newly diagnosed families, or contact us to speak to another parent.