Respiratory failure in infants due to spinal muscular atrophy with respiratory distress type 1

Background: Spinal muscular atrophy with respiratory distress type 1 (SMARD1) is a rare autosomal recessive neuromuscular disease of unknown prevalence characterized by degeneration of anterior horn alpha-motoneurons and manifesting in the first 6 months of life as life-threatening irreversible diaphragmatic paralysis associated with progressive symmetrical muscular weakness (distal lower limbs mainly involved), muscle atrophy, and peripheral sensory neuropathy. Setting: Pediatric intensive care unit of tertiary care hospital. Patients: We present two new cases of SMARD1 and report two new mutations in the gene IGHMBP2 which encodes immunoglobulin mu-binding protein 2 on chromosome 11q13. Conclusions: SMARD1 is a poor-prognosis disease that should be considered when acute respiratory insufficiency, of suspected neuromuscular or unclear cause, develops during the first 6 months of life. Diaphragmatic paralysis, manifesting as dyspnea and paradoxical respiration, is the most prominent presenting sign and diaphragmatic motility should be investigated early by fluoroscopy or ultrasound. Electromyography and nerve conduction studies revealing peripheral motor and sensory neuropathy then suggest the diagnosis which should be confirmed by genetic analysis.