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Spinal muscular atrophy (SMA) is a hereditary genetic disease characterised by the progressive destruction of the nerve cells that control the body's movements. Until now, treatments were implemented after birth to try to slow the progression of the disease.
For the first time, the Food and Drug Administration has authorised a clinical protocol for in utero treatment on a foetus diagnosed with type 1 spinal muscular atrophy, which in its most severe forms limits life expectancy to 2 years. The results published in February 2025 in the New England Journal of Medicine suggest new avenues for the prenatal treatment of this disease.
This disease is caused by a mutation of the SMN1 gene (for Survival Motor Neuron) which causes severe and progressive muscle weakness that most often begins in the first six months of life. In a press release, scientists at St Jude's Hospital in Memphis, Tennessee, emphasise that the earlier treatment is given - before the first symptoms appear - the greater the chances that children will develop normally.
After an amniocentesis confirmed that the foetus did not have a copy of the SMN1 gene, ‘which (...) indicated a very high risk that the infant would be born with type 1 SMA’, the doctors, at the request of the parents who had already lost a child to this disease, opted for treatment during pregnancy with Risdiplam. This medication, administered to the mother, has the particularity of passing through the placenta to reach the foetus.
It was administered orally from the 32nd week of pregnancy until the birth of the child, at 38 weeks of pregnancy. Rispdiplam was then administered directly to the child 8 days after birth and until the age of 30 months, when the results of the treatment were published.
To date, no symptoms of spinal muscular atrophy such as muscle weakness, absence of reflexes or breathing difficulties have been observed in the child, who is now two and a half years old. Although this treatment, carried out on a single case of spinal muscular atrophy, still needs to be studied more widely, it is an encouraging avenue for the in utero treatment of type 1 spinal muscular atrophy.
Image by Marjon Besteman from Pixabay