Age and baseline values predict 12 and 24-month functional changes in type 2 SMA

Area of Science:

• Neurology
• Genetics
• Pediatrics

Background:

• Spinal Muscular Atrophy (SMA) is a genetic neuromuscular disorder affecting motor neuron survival.
• Type 2 SMA presents with significant functional limitations and requires long-term monitoring.
• Understanding functional trajectories is crucial for predicting disease progression and managing patient care.

Purpose of the Study:

• To determine the range of functional changes in type 2 SMA patients over 12 and 24 months.
• To identify predictors of functional decline in this patient cohort.
• To analyze the impact of age and baseline functional status on disease progression.

Main Methods:

• Retrospective analysis of functional data from 267 type 2 SMA patients.
• Utilized Hammersmith Functional Motor Scale Expanded (HFMSE) assessments at 12 and 24-month intervals.
• Subdivided patients by functional level, Survival of Motor Neuron (SMN) copy number, and age.

Main Results:

• Stable HFMSE scores (± 2 points) were observed in 68% at 12 months and 55% at 24 months.
• Functional decline (≥ 2 points) occurred in 21% at 12 months and 35% at 24 months.
• Increased risk of functional loss was associated with older age and higher baseline HFMSE scores, particularly in older children and adolescents.

Conclusions:

• Functional decline is a significant concern in type 2 SMA, increasing over time.
• Age and baseline HFMSE scores are key predictors of functional deterioration.
• Combining age and baseline HFMSE enhances the prediction of disease progression in type 2 SMA.