Diaphragmatic paralysis due to spinal muscular atrophy

Infantile spinal muscular atrophy with respiratory distress type 1 (SMARD1)

Autosomal recessive spinal muscular atrophy with respiratory distress type 1 (SMARD1) is the second anterior horn cell disease in infants in which the genetic defect has been defined. SMARD1 results from mutations in the gene encoding the immunoglobulin micro-binding protein 2 (IGHMBP2) on chromosome 11q13. Our aim was to review the clinical features of 29 infants affected with SMARD1 and report on 26 novel IGHMBP2 mutations. Intrauterine growth retardation, weak cry, and foot deformities were the earliest symptoms of SMARD1. Most patients presented at the age of 1 to 6 months with respiratory distress due to diaphragmatic paralysis and progressive muscle weakness with predominantly distal lower limb muscle involvement. Sensory and autonomic nerves are also affected. Because of the poor prognosis, there is a demand for prenatal diagnosis, and clear diagnostic criteria for infantile SMARD1 are needed. The diagnosis of SMARD1 should be considered in infants with non-5q spinal muscular atrophy, neuropathy, and muscle weakness and/or respiratory distress of unclear cause. Furthermore, consanguineous parents of a child with sudden infant death syndrome should be examined for IGHMBP2 mutations.

Congenital peripheral neuropathy presenting as apnoea and respiratory insufficiency

A seven-week-old girl presented with recurrent apnoeic episodes and respiratory insufficiency. The child was hypotonic, weak, areflexic and had a paradoxical movement of the right hemidiaphragm. Cranial nerve and sphincter function was normal; there was no fasciculation. Nerve conduction studies showed a severe axonal sensory and motor peripheral neuropathy. Biopsy of the sural nerve revealed marked axonal atrophy. The infant is now over two years of age, is ventilator-dependent and has clinical and electrophysiological evidence of further progression of one of the earliest reported presentations of a congenital peripheral neuropathy.