Abstract
Spinal muscular atrophy (SMA) has gained much attention in the last few years because of the approval of the first intrathecal treatment for this neurodegenerative disease. Latin America needs to develop the demographics of SMA, timely access to diagnosis, and appropriate following of the standards of care recommendations for patients. These are essential steps to guide health policies. This was a descriptive study of a cohort of SMA patients from all over Chile. We analyzed the clinical, motor functional, and social data, as well as the care status of nutritional, respiratory and skeletal conditions. We also measured the SMN2 copy number in this population. We recruited 92 patients: 50 male; 23 SMA type-1, 36 SMA type-2 and 33 SMA type-3. The median age at genetic diagnosis was 5, 24 and 132 months. We evaluated the SMN2 copy number in 57 patients. The SMA type-1 patients were tracheostomized and fed by gastrostomy in a 69.6 % of cases, 65% of SMA type-2 patients received nocturnal noninvasive ventilation, and 37% of the whole cohort underwent scoliosis surgery. Ventilatory care for SMA type-1 is still based mainly on tracheostomy. This Chilean cohort of SMA patients had timely access to genetic diagnosis, ventilatory assistance, nutritional support, and scoliosis surgery. In this series, SMA type-1 is underrepresented, probably due to restrictions in access to early diagnosis and the high and early mortality rate.
Highlights
Spinal muscular atrophy (SMA) has gained much attention in the last few years because of the approval of the first intrathecal treatment for this neurodegenerative disease
The patients were recruited through the family association for SMA, (FAME Chile), a well-coordinated social organization that has succeeded in enrolling a significant number of SMA patients all over the country
We estimate a prevalence between 180 and 360 patients are affected by this disorder in our country, according to the Chilean population, assuming we have a prevalence of the disease similar to most countries[2,21]
Summary
Patient recruitment The SMA patients were recruited consecutively between and 2016, as part of a nationwide vigilance program of SMA status, with the support of an institutional research grant funding. Two expert physiotherapists, trained in functional motor scales, evaluated patients who consented to participate, using the Hammersmith (HFMS) and Motor Function Measure (MFM-32) for patients from 6-60 years of age and the short version MFM-20, for children older than three years and under six years of age. These two evaluations were performed on the same day for each patient[18,19,20]. Molecular study After receiving the informed consent, we obtained a peripheral blood sample to extract genomic DNA from patients, and to assess the number of copies of SMN1 and SMN2. Two independent experiments were performed to confirm results obtained by MLPA analysis
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