Background: Spinal muscular atrophy (SMA) is a rare neuromuscular disorder that can lead to a variety of complications. Rates of autism are increasing in the general population. The prevalence of autism and cognitive delay in SMA patients is not well-established, and there is a need for further research in this area.
Objective: To determine the rates of autism and cognitive delay in SMA patients at a single center over a one-year period, and to explore the association between these neurodevelopmental disorders and exposure to different SMA treatments.
Methods: A retrospective review of medical records was conducted for all SMA patients seen at a single center over a one-year period. Data collected included demographics, clinical features, diagnostic assessments for autism and cognitive delay, and exposure to different SMA treatments.
Results: A total of 75 SMA patients were seen at the center during the study period. Sixteen (21.3%) patients were found to have with autism or cognitive delay. The prevalence of autism in the general population in Florida is about 5%. The rates of autism and cognitive delay in SMA patients in this study were significantly higher than the general population rates.
Of the 16 patients with autism, 7 were exposed to Nusinersen only, 4 were exposed to Risdiplam only, 2 were exposed to Onasemnogene Abeparvovec and Risdiplam, 2 were exposed to Nusinersen and Risdiplam, and one patient was exposed to all three commercially available medications. Of the 16 patients with autism, 9 (56.3%) had 2 SMN2 copy numbers, 6 (37.5%) had 3 SMN2 copy numbers, and 1 (6.3%) had >3 SMN2 copy numbers.
There was no significant association between exposure to any particular SMA treatment and the diagnosis of autism or cognitive delay. However, the study was limited by its small sample size and retrospective design. Conclusions about association with SMN2 copy number cannot be made.
Conclusion: The rates of autism and cognitive delay in SMA patients are higher at our center than would be predicted by the general population of Florida. Further research is needed to better understand the relationship between SMA and these neurodevelopmental disorders, as well as the potential impact of different SMA treatments or modifier genes on these outcomes.