A male infant presents with severe hydrocephalus and respiratory distress. ### Prenatal and birth history On physical examination, the infant’s weight is 4,772 g, length is 51.5 cm, and head circumference is 45 cm. The most remarkable finding is hydrocephalus , and the infant has adducted thumbs. Over the first several postnatal days, the infant experiences progressively worsening respiratory distress and eventually develops a right-sided pneumothorax that requires intubation and mechanical ventilation. He is treated with inhaled nitric oxide for …