Acrofacial Dysostosis: An Overview

Acrofacial dysostosis is an umbrella term for several apparently distinctive genetic modifications. The disorder is characterized by distinctive craniofacial malformations, especially involving severe mandibular hypoplasia and preaxial and postaxial limb defects.

There are six types of acrofacial dysostosis.

• Acrofacial dysostosis, Nager type (mandibulofacialdysostosis, split-hand deformity-mandibulofacial dysostosis)
• Acrofacial dysostosis lethal type of Rodriguez
• Acrofacial dysostosis, Weyers type (Weyers syndrome II)
• Acrofacial dysostosis postaxial, Miller type (Miller syndrome)
• Acrofacial dysostosis, Catania type
• Acrofacial dysostosis, Palagonia type

All acrofacial dysostosis types are inherited as either autosomal dominant or recessive pattern.

Nager acrofacial dysostosis is a rare hereditary disorder marked by unusual facial development. Cleft lip/palate, defective development of bones in the jaw and arms, smaller than normal thumbs, hearing loss, and ear deformities are characteristics of this disorder.

Acrofacial dysostosis lethal type of Rodriguez is inherited as an autosomal recessive trait and is characterized by small stature, severe mandibular hypoplasia (micrognathia), phocomelia and oligodactyly of the upper limbs, absence of fistula, microtia, and cleft palate. Limb deficiencies are predominantly preaxial. The skin is thin and atrophic, vessels can be seen over the trunk, and elastosis perforans is present. There is a severe hypoplasia of the shoulder and pelvic girdles. Other features are severe internal organ anomalies, including arrhinencephaly and abnormal lung lobulation. The cardiovascular system presents congenital anomalies. The disorder is associated with early lethality. Most patients die of respiratory complications during the neonatal period, partly because of the presence of severe mandibular hypoplasia.

Weyers acrofacial dysostosis is present from birth, affects both sexes, and is characterized by postaxial polydactyly of the hands and feet, hexadactyly and fusion of fifth and sixth metatarsals and metacarpals and bony clefts of the mandibular symphysis. Other features include orodental anomalies, hypoplastic and dysplastic nails, short stature, micrognathia, small mouth, hypoplasia of the larynx. Congenital heart defect may be present.

Miller acrofacial dysostosis is thought to be inherited as an autosomal recessive trait and is apparent at birth. It is characterized by postaxial acrofacial dysostosis, which is defined by its postaxial limb deficiency. Craniofacial malformations, malar hypoplasia, severe micrognathia, cleft palate, small, protruding, “cup-shaped” ears, colobomas, drooping of the lower eyelids, and ectropion are seen. The limb abnormalities in infants and children may include severe hypoplasia, syndactyly, and/or absence of certain fingers and toes (e.g., fifth digits and, in some cases, fourth and third digits). Hypoplasia of the ulna and radius causes the forearms to appear unusually short.

Catania acrofacial dysostosis was reported in 1993 as a “new” form of acrofacial dysostosis. It is characterized by mild intrauterine growth retardation and postnatal shortness of stature, severe microcephaly, widow's peak, mandibulofacial dysostosis without cleft palate, mild preaxial, and especially more conspicuous postaxial upper limb involvement with short hands, simian creases, and mild interdigital webbing. Other features include genitourinary and gastrointestinal dysfunctions, such as hypospadias, cryptorchidism, and diversified hernias. Although the disorder is believed to be transmitted via an X-linked dominant inheritance, an autosomal dominant genetic transmission is highly possible considering that, in this report, the mother was severely affected. Most patients presented with extensive caries.

Palagonia acrofacial dysostosis affects patients who present with normal intelligence compared with the Sicilian type, Catania. This form of acrofacial dysostosis does not feature severe caries but rather oligodontia, short stature, frizzy hair with aplatis cutis verticis, mild cutaneous syndactyly of digits 2 to 5, and cleft lip/palate. Other features include abnormalities of the skeletal system, such as a small odontoid process and spina bifida occulta at S1. The inheritance pattern has been suggested to be X-linked dominant genetic transmission, but an autosomal dominant inheritance is favored by some.

The main consideration with any type of acrofacial dysostosis remains airway management. Preparation for difficult tracheal intubation is essential. A nasopharyngeal approach (fiberoptic) and/or laryngeal mask airway should be ready for use. Special intubation devices, such as fiberoptic laryngoscope, Bullard laryngoscope, and light wand, must be readily available. Spontaneous ventilation should be maintained until the airway is secure. The presence of an otorhinolaryngologist who can perform emergency tracheostomy must be planned in case all other attempts to secure the airway fail. Venous access can be difficult because of limb defects. The potential presence of cardiovascular and pulmonary problems must be assessed prior to induction of anesthesia.

Treacher Collins Syndrome is characterized by underdevelopment of the malar, mandibular, and maxillary bones, slanted eyes, notching of lower eyelids, and a receding chin. Underdevelopment of the jaw may cause problems in swallowing or breathing in the newborn. Malformed ear pinna usually is present. The presence of a normal face with a beak-like nose, receding chin, and acute deafness are characteristic of people with Treacher Collins syndrome.

Goldenhar Syndrome is a rare congenital disorder that includes partial absence of the upper eyelid or an unusual slant of the eyelid, asymmetry of the skull, sharply prominent forehead, absent or closed nostrils, and cleft palate.

Oral-Facial-Digital Syndrome (OFD) is a rare genetic disorder characterized by episodes of neuromuscular disturbances, split tongue, splits in the jaw, midline cleft lip, overgrowth frenulum, broad-based nose, epicanthic folds, polydactyly, and clinodactyly.

Juberg-Hayward Syndrome is a rare hereditary disorder characterized by cleft lip/palate, a smaller-than-normal-size head, deformities of the thumbs and toes, and growth hormone deficiency resulting in short stature.

Hemifacial Microsomia (HFM) Syndrome affects 1:5000 births. It can be confused with a Treacher Collins-like syndrome. However, it is not genetic. The syndrome can cause abnormalities that are always uneven on both sides of the face, whereas both sides of the face appear equally affected in Treacher Collins syndrome. The facial nerve is frequently paralyzed in hemifacial microsomia. Features include mandibular underdevelopment, microtia, facial nerve paresis in 40% of patients, macrostomia, and underdevelopment of the cheek and eye on the affected side of the face. Less common are abnormalities of the vertebrae and ribs, cleft lip/palate, and heart and kidney abnormalities, which are very rare.