François dyscephalic syndrome
Hallermann-Streiff-François (HSF) syndrome is marked by a characteristic facies with hypoplastic mandible and beaked nose, proportionate short stature (2/3), hypotrichosis (80%), microphthalmia (80%) with congenital cataract (80-90%), hypodontia (80%), hypotrichosis (80%), skin atrophy of the face (70%) and hypoplasia of the clavicles and ribs. About 15% of cases display intellectual deficit. Neonatal teeth may be present. Less than 100 cases have been reported so far in the literature and the vast majority of cases are sporadic. The genetic basis is still unknown. Upper airway obstruction may result from small nares and glossoptosis (tongue falling backwards) secondary to micrognathia, and these may lead to cor pulmonale. Snoring and/or daytime hypersomnolence are indications for sleep studies. Tracheomalacia is a complication that can lead to chronic respiratory insufficiency, resulting in biventricular cardiac failure and early death. Severe and lethal forms of HSF exist, with slender long bones and underossified skull, but it is not clear whether they are the same disorder, as these lethal forms (referred to as osteocraniostenosis) are recessively inherited. Differential diagnosis should be made with the other forms of progeroid syndromes (Hutchinson-Gilford progeria, Werner syndrome, acromandibular dysplasia) and oculodentodigital dysplasia.