This X-linked disorder primarily affects males with female carriers usually being asymptomatic. Respiratory distress, hypotonia , and muscle weakness are common manifestations in the newborn period for all three forms of the disorder (mild, moderate and severe). The severe form can present prenatally with polyhydramnios and decreased fetal movement; these patients may require a ventilator permanently. Motor milestones can range from mildly delayed to significantly delayed with some patients never being able to ambulate. The muscle weakness can also involve the facial and extraocular muscles. Mildly affected patients may only need ventilator support in the neonatal period and achieve ambulation.