*Correspondence: elice.batista@einstein.br.
Abstract
Background: Spinal muscular atrophy (SMA) is a rare disease characterized by progressive loss
of motor neurons located in the anterior horn of the spinal cord and brainstem, leading
to progressive muscle atrophy and weakness. The most common form of SMA (5q SMA) is
caused by bi-allelic mutations in the SMN1 gene on chromosome 5q13.2, classified into
subtypes, according to the age of onset and the maximum motor function achieved. The
journey to diagnosis can last for years and have a wide and significant impact on
patients' lives.
Objective: To map the time interval between the appearance of the first signs and symptoms and
the achievement of the 5q SMA diagnosis using a genetic report in Latin American patients
with 5q SMA.
Methods: This study is a clinical multicounty registry for SMA diseases that includes patients
with 5q SMA types 1, 2, and 3 of all ages and both sexes, treated in six Latin American
countries (Argentina, Brazil, Chile, Colombia, Mexico, and Uruguay). The time interval
between the appearance of the first signs and symptoms until obtaining the confirmatory
genetic diagnosis of 5q SMA will be analysed.
Results: Currently 213 participants were included (Argentina: 27, Brazil: 136, Colombia: 33,
Chile: 17), with an average age of 13.7 (years), being 99 (46.5%) female and 114 (53,5%)
male. The study is ongoing, and it is intended to reach around 300 participants in
the next 3 months. Preliminary results show subtype 2(45.5%) constitutes the largest
number of participants in this study, followed by subtypes 3(38.0%) and 1(16.4%).
The mean time to reach the confirmatory molecular report of 5q SMA varies greatly
across countries. Of the patients included in the study so far, 134 (63%) use or have
had access to disease modifying therapy for SMA and 79 (37%) never had access. Analysing
the reality of how long these patients take to confirm the genetic diagnosis of SMA
5q is of great relevance for greater assertiveness in the clinical management of the
disease and access to treatments that modify the course of the disease.
Conclusion: 5q SMA is a progressive degenerative disease, and it is of fundamental importance
that diagnostic confirmation occurs as early as possible. Knowing the time profile
of patients with 5q SMA diagnosis in Latin America is of fundamental importance for
us to advance in screening strategies essential to improve patient care. This study
is supported by Biogen.