<unk>  (; abbreviated<unk>  is a congenital defect observed in humans which is characterized by facial abnormalities. The three main features are micrognathia (abnormally small mandible), which causes glossoptosis (downwardly displaced or retracted tongue), which in turn causes breathing problems due to obstruction of the upper airway. A wide, U-shaped cleft palate is commonly also present.<unk>  is not merely a syndrome, but rather it is a<unk> —a series of specific developmental malformations which can be attributed to a single cause.
Pierre Robin sequence
First arch syndrome
Roberts syndrome
XK aprosencephaly
Cleidocranial dysostosis
Spina bifida
Marden–Walker syndrome
Trismus pseudocamptodactyly syndrome