DYNC1H1 and intellectual disability, autosomal dominant 13: Mutations in the cytoplasmic dynein 1 heavy chain gene (DYNC1H1) have been identified in rare neuromuscular (NMD) and neurodevelopmental (NDD) disorders such as spinal muscular atrophy with lower extremity dominance (SMALED) and autosomal dominant mental retardation syndrome 13 (MRD13).