Agnathia-holoprosencephaly-situs inversus syndrome

Agnathia-holoprosencephaly-situs inversus syndrome, also known as agnathia-otocephaly complex or otocephaly, is an extremely rare and typically lethal congenital malformation syndrome. It is characterized by three cardinal features: agnathia (absence or severe underdevelopment of the mandible/lower jaw), holoprosencephaly (a failure of the forebrain to properly divide into two hemispheres), and situs inversus (a mirror-image reversal of the normal positioning of internal organs). The condition profoundly affects craniofacial development, the central nervous system, and visceral organ arrangement. Key clinical features include absence or severe hypoplasia of the mandible, microstomia (abnormally small mouth) or astomia (absence of the mouth), synotia (fusion or medial displacement of the ears, sometimes beneath the chin), and varying degrees of holoprosencephaly ranging from alobar to semilobar forms. Additional findings may include cyclopia or other ocular anomalies, absence of the tongue (aglossia), and abnormalities of the pharynx and upper airway. Situs inversus totalis or other laterality defects are variably present. The condition is almost invariably fatal in the perinatal period due to severe airway compromise and brain malformations. The etiology remains incompletely understood. Most reported cases are sporadic, though some evidence suggests possible autosomal recessive inheritance in rare familial cases. Mutations in the PRRX1 gene have been implicated in some cases of otocephaly. Diagnosis is typically made prenatally via ultrasound or at birth based on the characteristic physical findings. There is no curative treatment; management is supportive and palliative. Genetic counseling is recommended for affected families.

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