Successful prenatal spinal muscular atrophy treatment

Spinal muscular atrophy (SMA) is a genetic disease which affects the nervous system and skeletal muscles. Moreover, the age of SMA symptom onset correlates with the degree of altered motor function. In 2025, for the first time, in utero prenatal treatment with risdiplam was successful in the United States of America.

SMA is a 𝐫𝐚𝐫𝐞 𝐝𝐢𝐬𝐞𝐚𝐬𝐞 leading to motor neuron loss and 𝐦𝐮𝐬𝐜𝐥𝐞 𝐚𝐭𝐫𝐨𝐩𝐡𝐲. This pathology is the most common 𝐠𝐞𝐧𝐞𝐭𝐢𝐜 𝐜𝐚𝐮𝐬𝐞 of infant death, although it may appear later in life. The earlier the onset of symptoms, the more severe the symptoms. SMA is the result of a mutation in the 𝑆𝑀𝑁1 gene, which encodes the 𝐒𝐌𝐍 𝐩𝐫𝐨𝐭𝐞𝐢𝐧. This protein is crucial for 𝐦𝐨𝐭𝐨𝐫 𝐧𝐞𝐮𝐫𝐨𝐧 𝐬𝐮𝐫𝐯𝐢𝐯𝐚𝐥. The 𝑆𝑀𝑁2 gene is also involved. Depending on the type of SMA, 1 person out of 6,000 to 10,000 is impacted.

In an article published in the 𝑁𝑒𝑤 𝐸𝑛𝑔𝑙𝑎𝑛𝑑 𝐽𝑜𝑢𝑟𝑛𝑎𝑙 𝑜𝑓 𝑀𝑒𝑑𝑖𝑐𝑖𝑛𝑒 shares the case of the 𝐟𝐢𝐫𝐬𝐭 𝐟𝐞𝐭𝐮𝐬 𝐰𝐢𝐭𝐡 𝐒𝐌𝐀 𝐭𝐫𝐞𝐚𝐭𝐞𝐝 𝒊𝒏 𝒖𝒕𝒆𝒓𝒐. Given the previous history of SMA among siblings, 𝐚𝐦𝐧𝐢𝐨𝐜𝐞𝐧𝐭𝐞𝐬𝐢𝐬 was performed and identified Type I SMA on the fetus. Risdiplam was administered during the last 6 weeks of the pregnancy and the little girl was 𝐛𝐨𝐫𝐧 𝐰𝐢𝐭𝐡𝐨𝐮𝐭 𝐒𝐌𝐀 𝐬𝐲𝐦𝐩𝐭𝐨𝐦𝐬, although several abnormalities were present and had most likely appeared early during the development. Treatment was started in the newborn at 8 days. At 2.5 years, she 𝐝𝐢𝐝 𝐧𝐨𝐭 𝐬𝐡𝐨𝐰 𝐜𝐥𝐢𝐧𝐢𝐜𝐚𝐥 𝐬𝐢𝐠𝐧𝐬 or results suggestive of SMA.

This first 𝑖𝑛 𝑢𝑡𝑒𝑟𝑜 treatment success is 𝐯𝐞𝐫𝐲 𝐞𝐧𝐜𝐨𝐮𝐫𝐚𝐠𝐢𝐧𝐠. Moreover, screening programs are of utmost importance as 60% of babies die within the first two years of life without treatment. In France, although these programs have been implemented 𝐢𝐧 𝐬𝐞𝐯𝐞𝐫𝐚𝐥 𝐫𝐞𝐠𝐢𝐨𝐧𝐬, a national screening program is still in the process of being set up.