Functional class criteria identification in patients with spinal muscular atrophy 5q

Spinal muscular atrophy 5q (SMA) is one of the most common inherited neuromuscular diseases in children with an autosomal recessive type of inheritance. Homozygous deletion of exons 7 or 7–8 of the SMN1 gene encoding the motor neuron survival protein is responsible for 95 % of cases. SMA is characterized by a steadily progressive course with the development of paresis, muscle atrophy, loss of previously acquired motor skills, respiratory failure and skeletal deformities. The introduction of pathogenetic therapy in recent years has significantly changed the trajectory of SMA – patients survive, restore previously lost motor skills and acquire new ones. The clinical classification, which includes 5 types of SMA, is currently not a reliable reflection of the functional state of the child in dynamics. In 2005, a functional classification was recommended based on the patient’s current status: non-sitters (lying), sitters, and walkers. The article provides a summary of historical concepts regarding functional classification in SMA patients, as well as the criteria used in clinical trials and observations. We proposed criteria for categorizing SMA patients into a specific functional class by analyzing the available literature and making recommendations on using the classification in real clinical practice.