has material basis in has symptom spinal muscular atrophy with lower extremity predominant spinal muscular atrophy with lower extremity predominant 2A disease_ontology DOID:0070349 MIM:615290 A spinal muscular atrophy with lower extremity predominance that is characterized by early childhood onset of muscle weakness and atrophy predominantly affecting the proximal and distal muscles of the lower extremity, although some patients may show upper extremity involvement and that has_material_basis_in heterozygous mutation in the BICD2 gene on chromosome 9q22. spinal muscular atrophy with lower extremity predominance 2A autosomal dominant inheritance muscle weakness