H49R MUTATION OF THE SOD1 GENE AS A CAUSE OF PROGRESSIVE MUSCULAR ATROPHY: A CLINICAL CASE

Amyotrophic lateral sclerosis (ALS) is a severe neurodegenerative disease within the spectrum of motor neuron disorders, selectively targeting central and peripheral motor neurons in the brain and spinal cord, with highly variable clinical manifestations. One rare form of ALS is progressive muscular atrophy (PMA), primarily characterized by the selective involvement of peripheral motor neurons and a slower, less aggressive progression compared to classical ALS. Currently, the scientific community lacks consensus on whether PMA should be classified as a distinct nosological entity or as a subtype of ALS. Recent advancements in genetic research have identified that familial and hereditary forms of ALS are most frequently linked to mutations in the SOD1, TARDBP, C9orf72, and FUS genes, among others. Moreover, increasing progress in genetic testing now enables the identification of mutant genes responsible for various phenotypes. Understanding the genetic underpinnings of motor neuron diseases is crucial for elucidating their pathogenesis, which may pave the way for the development of novel diagnostic and therapeutic strategies. This article presents a clinical case involving a patient with a PMA phenotype associated with the H49R mutation in the SOD1 gene. A comprehensive account of the patient’s anamnesis, clinical presentation, molecular-genetic findings, as well as results from instrumental investigations, including electromyography and magnetic resonance imaging, is provided. The article discusses the potential nosological autonomy of PMA and its association with the H49R mutation, referencing current data from both Russian and international studies. Additionally, the article highlights the challenges of differential diagnosis, particularly in distinguishing PMA from other neurodegenerative diseases with similar clinical profiles. This case contributes to the expanding knowledge of the heterogeneity of motor neuron diseases and underscores the importance of molecular-genetic testing in predicting disease prognosis and guiding patient management.