Apert syndrome

Apert syndrome is a form of acrocephalosyndactyly, a congenital disorder characterized by malformations of the skull, face, hands and feet. It is classified as a branchial arch syndrome, affecting the first branchial (or pharyngeal) arch, the precursor of the maxilla and mandible. Disturbances in the development of the branchial arches in fetal development create lasting and widespread effects.

Overview

In 1906, Eugène Apert, a French physician, described nine people sharing similar attributes and characteristics.^[1]. Linguistically, “acro” is Greek for “peak,” referring to the “peaked” head that is common in the syndrome. “Cephalo”, also from Greek, is a combining form meaning “head”. “Syndactyly” refers to webbing of fingers and toes.

In embryology, the hands and feet have selective cells that die, called selective cell death or apoptosis, causing separation of the digits. In the case of acrocephalosyndactyly, selective cell death does not occur and skin, and rarely bone, between the fingers and toes fuses.

The cranial bones are affected as well, similar to Crouzon syndrome and Pfeiffer syndrome. Craniosynostosis occurs when the fetal skull and facial bones fuse too soon in utero, disrupting normal bone growth. Fusion of different sutures leads to different patterns of growth on the skull. Examples include: trigonocephaly (fusion of the metopic suture), brachycephaly (fusion of the coronal suture), dolichocephaly (fusion of the sagittal suture), plagiocephaly (fusion of coronal and lambdoidal sutures unilaterally), and oxycephaly or turricephaly (fusion of coronal and lambdoid sutures).

Apert syndrome occurs in approximately 1 per 160,000 to 1 per 200,000 live births.^[2]

Causes

Acrocephalosyndactyly may be an autosomal dominant disorder. Males and females are affected equally; however research is yet to determine an exact cause. Nonetheless, almost all cases are sporadic, signifying fresh mutations or environmental insult to the genome. The offspring of a parent with Apert syndrome has a 50% chance of inheriting the condition. In 1995, A.O.M. Wilkie published a paper showing evidence that acrocephalosyndactyly is caused by a defect on the fibroblast growth factor receptor 2 gene, on chromosome 10.^[3]

A child with Apert syndrome

Symptoms

The cranial malformations are the most apparent effects of acrocephalosyndactyly. Cranialsynostosis occurs, with brachiocephaly being the common pattern of growth. Another common characteristic is a high, prominent forehead with a flat posterior skull. Due to the premature closing of the coronal sutures, increased cranial pressure can develop, leading to mental deficiency. A flat or concave face may develop as a result of deficient growth in the mid-facial bones, leading to a conditir prognathism. Other features of acrocephalosyndactyly may include shallow bony orbits and broadly spaced eyes. Low-set ears are also a typical characteristic of branchial arch syndromes.

The major attribute of the syndrome is syndactyly of the hands and feet. Commonly there is fusion of fingers or toes with an equal number on both sides of the body. Those with Aperts syndrome may also show Synonychia, the fusion of two or more nails of the digits. It is typical for the middle 3 fingers to be fused together. The thumb and big toe may be broad and malformed. Apert syndrome is progressive with age as the joints continue to grow, but remain immovable.

Treatments

Surgery is needed to prevent the closing of the coronal sutures from damaging brain development. Combined orthodontic and orthognathic surgery can help relieve some facial deformities, such as the flat or concave face. In particular, the LeFort III, a surgical procedure, detaches the midface from the rest of the skull in order to reposition it in the correct plane. Aggressive surgery is needed to separate as many fingers and toes as possible.

Dental significance

Common relevant features of acrocephalosyndactyly are a high-arched palate, pseudomandibular prognathism (appearing as mandibular prognathism), a narrow palate, and crowding of the teeth.

See also

• Crouzon syndrome
• Pfeiffer syndrome
• Hearing loss with craniofacial syndromes
• Saethre-Chotzen syndrome

References

1. ^ synd/194 at Who Named It?
2. ^ Kaplan, L C (1991-04). "Clinical assessment and multispecialty management of Apert syndrome". Clinics in plastic surgery 18 (2): 217–25. ISSN 00941298. PMID 2065483. 
3. ^ Wilkie, A O; S F Slaney, M Oldridge, M D Poole, G J Ashworth, A D Hockley, R D Hayward, D J David, L J Pulleyn, P Rutland (1995-02). "Apert syndrome results from localized mutations of FGFR2 and is allelic with Crouzon syndrome". Nature genetics 9 (2): 165–72. doi:10.1038/ng0295-165. PMID 7719344. 

External links

• Information from Teeter's Page at www.apert.org
• Apert Syndrome information from Seattle Children's Hospital Craniofacial Center
• cleftAdvocate - Non-profit support organization for all craniofacial conditions; on-line and in-person family support, insurance and advocacy assistance, and more.
• The National Craniofacial Association
• A resource for information and support
• Short explanation