Craniofacial anomaly characterized by an antimongoloid
slant of the eyes, coloboma of the lid, micrognathia (can be severe),
microtia and other deformity of the ears, hypoplastic zygomatic arches, and
macrostomia. Conductive hearing loss and cleft palate are often present.
Treacher Collins syndrome
This 8-year-old boy shows the characteristic facial features of Treacher
Collins syndrome: antimongoloid slanting of the palpebral fissures, lower
eyelid coloboma, hypoplastic zygomatic arches, microtia with atresia of the
external auditory meatus, and mandibular hypoplasia. The wire behind his
left ear connects to an endocochlear implant hearing aid.
Berry-Treacher-Collins Syndrome; Mandibulofacial Dysostosis; TCOF-I
An autosomal dominant transmission with high
penetrance and variable expressivity. The gene is localized on the long arm of
chromosome 5 (in 5q32-q33.1 locus region, also termed TCOF1 locus) and
produces a protein called the “treacle” gene.
Dysmorphogenesis of the first and second embryonal
branchial arch systems. It has been postulated that it results from a defect
in a nucleolar trafficking protein that is critically required during human
craniofacial development. Interestingly enough, the facial features are
strikingly similar to those observed with vitamin A toxicity in both animals
and humans born of a mother who took 2000 IU of vitamin A daily as a
supplement during pregnancy.
The diagnosis of these syndromes is based on the
clinical features. The radiographic studies may show poorly developed
supraorbital ridges, hypoplastic malar bones, hypoplasia of mandible, and
flat or aplastic coronoid and condyloid processes. Prenatal diagnosis is
possible by ultrasonographic examination (by the 20th week) and by molecular
biology on chorionic villus sample (as source of fetal DNA). All the
mutations currently reported suggest haploinsufficiency as the molecular
mechanism underlying the disorder. Laboratory and radiological findings,
which include supraorbital ridges, hypoplastic malar bones, hypoplasia of
mandible, aplastic coronoid and condyloid processes, and abnormal cranial
base (basilar kyphosis).
The eyes show several anomalies: antimongoloid
obliquity of palpebral fissures, coloboma of outer portion lower lids, with
a deficiency of cilia, absence of the lower lacrimal points,
microphthalmia. Flattening of the cheeks. Facial features: malar hypoplasia;
hypoplastic zygomatic arches; antimongoloid slant; lower eyelid coloboma;
microphthalmia; vision loss; strabismus; partial absence of lower eyelashes;
nystagmus; atresia of external auditory meatus; microtia; malpositioning or
maldevelopment of the pinna. Mouth: cleft palate, mandibular hypoplasia,
macrostomia, absence of parotid gland. Other clinical anomalies: cardiovascular defects; cervical
vertebral malformations; renal anomalies; choanal atresia; limb
malformations; early failure to thrive; learning disabilities in early life;
chronic respiratory insufficiency; cryptorchidism; psychological problems
and social stigma as a consequence of facial deformity; sleep apnea syndrome
and sudden death; conductive hearing loss; mental retardation.
Management of the airway is expected
to be difficult. Because of the mandibular retrusion and condylar hypoplasia,
tracheal intubation with a fiberoptic laryngoscope is necessary.