The ultrastructure of peripheral nerve, motor end-plate and skeletal muscle in patients suffering from spinal muscular atrophy with respiratory distress type 1 (SMARD1).

Spinal muscular atrophy with respiratory distress type 1 (SMARD1) is genetically and clinically distinct from classic spinal muscular atrophy (SMA1). It results from mutations in the gene encoding immunoglobulin mu-binding protein 2 (IGHMBP2) on chromosome 11q13. Patients develop distally pronounced muscular weakness and early involvement of the diaphragm, resulting in respiratory failure.