Autosomal dominant spinal muscular atrophy, lower extremity-predominant 2 (SMALED2) is a rare neurological disease characterized by early-childhood onset of muscle weakness and loss of muscle tissue (muscle atrophy), mostly affecting the muscles of the thighs. It is a subtype of the group of diseases known as spinal muscular atrophy. Symptoms include delayed walking, waddling gait, difficulty walking, foot deformities, and loss of some reflexes. Joint contractures are reported frequently, and a few patients present with congenital hip dysplasia. Other symptoms that have being described are an exaggerated curvature of the lower back (hyperlordosis), increased or decreased muscle tone, small chin (micrognathia), respiratory insufficiency, small head (microcephaly), and extra ridges or folds in the brain surface (polymicrogyria). Sensation and cognitive function are normal in most cases. Many patients show evident atrophy of the lower limbs and a very broad upper body, which resembles a bodybuilder-like shape. It is caused by genetic changes in the BICD2 gene. Inheritance is autosomal dominant.