Neonatal spinal muscular atrophy presenting as respiratory distress: a clinical variant.

Respiratory distress from diaphragmatic and intercostal muscular weakness was the presenting feature of two neonates with progressive spinal muscular atrophy, leading to death in the first 2 months of life. This atypical feature provides evidence of heterogeneity within the commonly used clarification of type 1 spinal muscular atrophy.