Amyotrophic Lateral Sclerosis 21, also known as amyotrophic lateral sclerosis type 21, is related to distal myopathy 2 and distal hereditary motor neuronopathy type 7, and has symptoms including upper motor neuron signs An important gene associated with Amyotrophic Lateral Sclerosis 21 is MATR3 (Matrin 3), and among its related pathways/superpathways is Amyotrophic lateral sclerosis (ALS). Affiliated tissues include spinal cord and skeletal muscle, and related phenotypes are dementia and distal sensory impairment