In what is being dubbed a medical marvel, doctors have managed to treat a deadly motor neuron disease in a baby who was still in the womb. The details have been published in The New England Journal of Medicine, which marks the first time that the condition, called spinal muscular atrophy (SMA) has been tackled before birth.

SMA is a genetic disorder that targets the motor neurons, limiting movement and weakening muscles over time. It is an extremely rare disease, occurring in just one out of every 10,000 live births. The child in this case had SMA type 1, the most common form of the disorder after undergoing genetic testing.

Notably, the parents already had one child pass away due to SMA type 1. The tests revealed that the fetus also had mutations in the SMN1 genes in both chromosomes.

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The procedure

The team intervened at 32-week gestation period by giving the mother risdiplam – a drug approved by the US Food and Drug Administration (FDA) for the treatment of SMA in infants. Up until now, the drug was only administered after birth but the doctors were permitted to give it to the mother with the baby still in the womb.

The mother took the drug daily for six weeks while the baby herself was given the drug orally, roughly one week after the birth. The doctors found that the infant had higher levels of SMN protein and less nerve damage than other babies born with SMA type 1. In the months since her birth has shown no signs of abnormal muscle development.

Although she may have to take risidiplam for the rest of her life, into adulthood while doctors closely monitor her for any changes in muscle development. As of the last update, the baby had shown no signs of the rare genetic disorder, nearly three years after being born.