Update and recommendations on genetic testing for amyotrophic lateral sclerosis in clinical practice: a Brazilian expert view.

Amyotrophic lateral sclerosis (ALS) is a complex and progressive neurodegenerative disorder characterized by the degeneration of both upper and lower motor neurons. Although most ALS cases occur sporadically, without a known family history of the disease, genetic factors play a major role in its pathogenesis through monogenic, oligogenic, or polygenic mechanisms. It is estimated that 10-15% of ALS cases occur in a familial setting; however, a specific monogenic cause cannot always be identified. Establishing the underlying genetic basis in both sporadic and familial ALS is essential, as it enables individualized and family genetic counseling, facilitates the early identification of at-risk or oligosymptomatic relatives, improves the prediction of gene-specific clinical trajectories, and, more recently, determines eligibility for gene-targeted therapies, such as tofersen for SOD1-associated ALS and ulefnersen, currently under clinical investigation, for FUS-associated ALS. Over the years, differing opinions have existed regarding the role of genetic testing in individuals diagnosed with ALS. However, accumulating clinical evidence has increasingly supported the timely and early implementation of genetic testing as part of the standard clinical management of patients with ALS. In this article, we present the perspective of leading Brazilian neurologists specializing in ALS care regarding the current role of genetic testing in clinical practice.