At Nature, science writer Smriti Mallapaty reports that a girl, now two and a half, has been cured — with treatment beginning during late gestation — of spinal muscular atrophy. A gene-targeting drug reversed the course of the often-fatal disease which affects 1 in 10,000 births):

In its most severe form, as in the case of this child, individuals lack both copies of the SMN1 gene, and have only one or two copies of a neighbouring gene, SMN2, that partially compensates for that deficiency. As a result, the body does not produce enough of the protein required for maintaining motor neurons in the spinal cord and brainstem. This protein is most important in the second and third trimesters, and the first few months of life. Babies with severe disease don’t usually live past their third birthday.

“Rare genetic disorder treated in womb for the first time,” February 20, 2025

The girl still takes medications but is said to be developing normally.

While drugs are commonly administered for SMA after birth, Mallapaty notes that the prenatal treatment was the parents’ idea. They had already suffered a loss from this disease and the FDA approved this single case:

The mother, who was 32 weeks pregnant, took Risdiplam daily for six weeks. The baby started taking the drug from roughly one week old, and will probably continue to take it for the rest of her life.

Tests of amniotic fluid and cord blood at delivery suggest that the drug was reaching the fetus. Compared with other babies born with the same condition, the child had higher levels of the SMN protein in the blood, and showed lower levels of nerve damage. The child has shown no signs of muscle weakness and has normal muscle development. “That’s obviously very reassuring,” says [Richard] Finkel, who recommends lifelong monitoring of the child. “Treated in womb”

Finkel, first author of a study of the case in the New England Journal of Medicine, hopes that this approach — start the treatment as early as possible — can be applied to other cases and other diseases as well.

You may also wish to read: There’s no science argument on whether unborn children are human. Neurosurgeon Michael Egnor notes that abortion activists argue that the embryo is a different species, some unclassified thing, or part of the mother — that’s politics, not science. He recounts that, while he always tells the truth to parents about their unborn babies’ neurological issues as he understands them, sometimes the children surprise him.