Infantile-onset X-linked spinal muscular atrophy

A rare form of spinal muscular atrophy characterized by the neonatal onset of severe hypotonia, areflexia, profound weakness, multiple congenital contractures, facial dysmorphic features (myopathic face with open, tent-shaped mouth), cryptorchidism, and mild skeletal abnormalities (i.e. kyphosis, scoliosis), that is often preceded by polyhydramnios and reduced fetal movements <i>in utero</i> and followed by bone fractures shortly after birth. Muscle weakness is progressive and chest muscle involvement eventually leads to ventilatory insufficiency and respiratory failure.