Agnathia-otocephaly (AGOTC) is a rare condition characterized by mandibular hypoplasia or agnathia, ventromedial auricular malposition (melotia) and/or auricular fusion (synotia), and microstomia with oroglossal hypoplasia or aglossia. Holoprosencephaly is the most commonly identified association, but skeletal, genitourinary, and cardiovascular anomalies, and situs inversus have been reported. The disorder is almost always lethal (review by Faye-Petersen et al., 2006).

Hypomandibular faciocranial syndrome consists of craniosynostosis, prominent eyes, deficient midface and zygomatic arches, short nose with anteverted nares, protruding lower face, minute oral aperture, persistent buccopharyngeal membrane, severe mandibular hypoplasia, and various extracephalic anomalies (summary by Gorlin et al., 2001).

Hypoglossia-hypodactyly syndrome is characterized by a hypoplastic mandible, absence of the lower incisors, hypoglossia, and a variable degree of absence of the digits and limbs. Intelligence is normal (Hall, 1971). Hall (1971) classified what he termed the 'syndromes of oromandibular and limb hypogenesis,' which comprised a range of disorders with hypoglossia in common. Type I included hypoglossia and aglossia in isolation. Type II included hypoglossia with hypomelia/hypodactylia. Type III included glossopalatine ankylosis with hypoglossia or hypoglossia and hypomelia/hypodactyly. Type IV included intraoral bands with fusion with hypoglossia or hypoglossia and hypomelia/hypodactyly. Type V included several syndromes, such as Hanhart syndrome, Pierre Robin syndrome (261800), Moebius syndrome (157900), and amniotic band syndrome (217100). Hall (1971) noted that complete aglossia or adactylia had not been reported, and suggested that 'hypoglossia-hypodactylia' is a more accurate term. See also hypoglossia and situs inversus (612776).