American clinicians report the observation, unique to date, of a child diagnosed with SMA in the neonatal period and then treated with gene therapy (Zolgensma® or onasemnogene abeparvovec), who presented neurological signs suggestive of spinal cord compression from the age of 14 months:
- the patient’s genotype was 0 copies of the SMN1 gene and 3 copies of the SMN2 gene.
- the tumour, a low-grade epithelioid neoplasm of the medulla resembling glial tumours, was surgically resected with postoperative recovery and disappearance of the signs of compression,
- it was not possible to state with certainty that the therapeutic transgene had been integrated into the genome at a site of tumorigenesis, but the association of the two events is nonetheless troubling.
This observation once again argues in favour of very regular monitoring of children with SMA treated with gene therapy.
