spinal muscular atrophy with respiratory distress type 2 (Monarch Disease Ontology entry MONDO_0018450) is a rare, genetic, motor neuron disease characterized by progressive early respiratory failure associated with diaphragm paralysis, distal muscular weakness, joint contractures, and axial hypotonia with preserved antigravity limb movements. Phenotype overlaps considerably with SMARD type 1 but is differentiated by a mutation in a different gene. Also known as: SMARD2, X-linked spinal muscular atrophy with respiratory distress, diaphragmatic spinal muscular atrophy type 2, severe infantile axonal neuropathy with respiratory failure type 2.