EFO_0010264 (spinal muscular atrophy, lower extremity-predominant, 2B, prenatal onset, autosomal dominant) is an autosomal dominant neuromuscular disorder characterized by decreased fetal movements, fractures in utero, severe congenital joint contractures, arthrogryposis multiplex congenita, severe hypotonia, muscle atrophy, and respiratory insufficiency and failure due to muscle weakness. Some patients may have dysmorphic facial features and/or abnormalities on brain imaging. Death in early childhood may occur.