Abstract
BackgroundSpinal muscular atrophy (SMA) is one of the most frequent and severe genetic diseases leading to premature death or severe motor disability. New therapies have been developed in recent years that change the natural history of the disease. The aim of this study is to describe patients included in the Polish Registry of SMA, with a focus on the course of type 3 SMA (SMA3) before the availability of disease-modifying treatments.Results790 patients with SMA were included in the registry (173 with type 1 [SMA1], 218 with type 2 [SMA2], 393 with SMA3, and six with type 4 SMA [SMA4]), most (52%) of whom were adults. Data on SMN2 gene copy number were available for 672 (85%) patients. The mean age of onset was 5 months for SMA1, 11.5 months for SMA2, and 4.5 years for SMA3. In patients with SMA3, the first symptoms occurred earlier in those with three copies of SMN2 than in those with four copies of SMN2 (3.2 years vs. 6.7 years). The age of onset of SMA3 was younger in girls than in boys (3.1 years vs. 5.7 years), with no new cases observed in women older than 16 years. Male patients outnumbered female patients, especially among patients with SMA3b (49 female vs. 85 male patients) and among patients with SMA3 with four copies of SMN2 (30 female vs. 69 male patients). 44% of patients with SMA3 were still able to walk; in those who were not still able to walk, the mean age of immobilization was 14.0 years. Patients with SMA3a (age of onset < 3 years) and three copies of SMN2 had significantly worse prognosis for remaining ambulant than patients with SMA3b (age of onset ≥ 3 years) and four copies of SMN2.ConclusionsThe Registry of SMA is an effective tool for assessing the disease course in the real world setting. SMN2 copy number is an important prognostic factor for the age of onset and ambulation in SMA3. Sex and age of disease onset also strongly affect the course of SMA. Data supplied by this study can aid treatment decisions.
Highlights
Spinal muscular atrophy (SMA) is one of the most frequent and severe genetic diseases leading to pre‐ mature death or severe motor disability
The aim of this study is to describe the patients included in the Polish Registry of SMA and to analyze the clinical course of SMA3 before disease-modifying treatment became available in Poland
Our registry-based study allowed us to characterize a large population of patients with SMA and describe the clinical course of SMA3 before the availability of pharmacotherapy
Summary
Spinal muscular atrophy (SMA) is one of the most frequent and severe genetic diseases leading to pre‐ mature death or severe motor disability. The aim of this study is to describe patients included in the Polish Registry of SMA, with a focus on the course of type 3 SMA (SMA3) before the availability of disease-modifying treatments. Registries of patients with rare disorders, such as neuromuscular diseases (NMDs), have an important role in monitoring the course of the disease, defining trial or treatment-ready population. In 2007, the Translational Research in Europe and Treatment of Neuromuscular Diseases (TREAT-NMD) project (http://www.treat-nmd.eu) was initiated as a European Committee-funded Network of Excellence to support translational research in the field of NMDs. An important tool to achieve the aims of the TREAT-NMD project was the creation of a global database of patients in national registries. Data have been collected, curated, and updated at a single neuromuscular referral center
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