Bone mineral density changes in patients on drug therapy for spinal muscular atrophy

Patients with Spinal Muscular Atrophy (SMA) are at higher risk of diminished bone health due to decreased ambulation and mobility. With the advent of new FDA-approved therapies, we aimed to analyze the effects of SMA therapy on bone mineral density (BMD) using dual energy X-ray absorptiometry (DXA) scan data of 27 patients diagnosed with SMA Type 1, 2, or 3. Patients were divided into those with DXA scans both before and after treatment (older cohort), and patients with first DXA post-treatment (cohort treated in infancy). In patients with DXA both before and after treatment, SMA drug therapy did not normalize (Z-score > -2) bone density in anyone with pre-established low bone mineral density. Patients with first DXA post-treatment initiation had a higher rate of normal bone mineral density compared to older cohort. Fractures were also tracked; frequency of fractures after therapy decreased from 52 % of patients to 14 % (p = 0.0584).