Prevalence of Spinal Muscular Atrophy in the Era of Disease-Modifying Therapies: An Italian Nationwide Survey.

OBJECTIVE
Spinal muscular atrophy (SMA) is a neurodegenerative disorder caused by mutations in the SMN1 gene. The aim was to assess the prevalence of SMA and treatment prescription in Italy.


METHODS
An online survey was distributed to 36 centers identified by the Italian government as referral centers for SMA. Data on number of SMA patients subdivided according to age, type, SMN2 copy number and treatment were collected.


RESULTS
1255 SMA patients are currently followed in the Italian centers with an estimated prevalence of 2.12/100000. Of the 1255, 284 were type I, 470 type II, 467 type III and 15 type IV with estimated prevalence of 0.48, 0.79, 0.79 and 0.02/100000 respectively. Three SMA 0 and 16 presymptomatic patients were also included.Around 85% were receiving one of the available treatments. The percentage of treated patients decreased with decreasing severity (SMA I: 95.77%, SMA II: 85.11%,SMA III: 79.01%).


DISCUSSION
The results provide for the first time an estimate of the prevalence of SMA at the national level and the current distribution of patients treated with the available therapeutical options. These data provide a baseline to assess future changes in relation to the evolving therapeutical scenario.