Study Description: Characterization of Motor Neuron Disease Phenotypes The goal of this observational study is to understand the clinical presentation of motor neuron disease (MND) in patients attending the Neurology Department of the Istituto Auxologico Italiano. The main questions it aims to answer are: * What are the specific clinical phenotypes associated with MND? * How can these phenotypes contribute to a better understanding of the disease's underlying mechanisms and improve prognostic accuracy? Participants will undergo: * Clinical evaluation using validated scales * Neurophysiological and neuroradiological instrumental assessment * Neuropsychological evaluation * Collection of biological materials for genetic screening and biomarker assessment, if necessary.