Pitt-Hopkins syndrome is characterized by mental retardation, hyperventilation, and dysmorphic features due to TCF4 mutations. We report a case of Pitt-Hopkins syndrome in a 2½-year-old boy presenting with psychomotor retardation, recurrent respiratory tract infections, and dysmorphic features with absence of hyperventilation or other breathing abnormalities. Comparative genomic hybridization and quantitative real-time polymerase chain reaction were used to confirm TCF4 haploinsufficiency. Pitt-Hopkins syndrome is a rare debilitating disease that should be in the differential diagnosis of other neurodevelopmental disorders characterized by mental retardation and hypotonicity despite the absence of hyperapnea and seizures. Quantitative real-time polymerase chain reaction is another method to identify TCF4 and to confirm Pitt-Hopkins syndrome diagnosis.
Keywords: 18-q syndrome; Pitt-Hopkins syndrome; TCF4; hyperventilation.