Pitt-Hopkins syndrome (PTHS) is a rare congenital dysmorphic syndrome with neurodevelopmental disturbances, which usually occurs sporadically. Mutations in the TCF4 gene located at 18q21.2 are the cause of this syndrome (an autosomal dominant de novo mutation). PTHS characterized by severe intellectual disability, specific breathing pattern (paroxysms of hyperpnea and apnea) and typical craniofacial dysmorphism. We report two patients with Pitt-Hopkins syndrome: proband 1 - 4 years of age female child with a new mutation in TCF4 gene and proband 2 - 22 months of age girl with a heterogeneous deletion of complete TCF4 gene. Additionally, we present a clinical follow-up of Pitt-Hopkins syndrome and a review of literature with special emphasis on differential diagnosis.