Apert's Syndrome - observation

Historical Overview

• Acrocephalosyndactyly, commonly known as Apert’s syndrome, is a rare craniofacial syndrome with an autosomal dominant pattern and a broad clinical spectrum with complex upper and lower limb anatomical deformities.¹
• In 1896, Eugene Apert encountered a child with severe congenital craniofacial and limb anomalies. He subsequently collected similar previously reported cases in the literature, and referred to the anomalies as “hereditary acrocephalosyndactyly,” publishing 9 cases in 1906. Eventually, this condition would become known as Apert’s syndrome.²
• Since Apert’s initial 1906 report, several papers have discussed classification systems and treatment strategies for the complex syndactylies present in Apert’s syndrome. In 1991, Upton provided the most detailed description of the anatomy of limbs in these patients, and this classification system is still commonly used today due to its simplicity, immediacy, and close correlation with the type of mutation.^2,3

Description

• Apert’s test is a component of the clinical examination performed on children with suspected Apert’s syndrome to confirm the diagnosis and classify it appropriately.

Pathophysiology

• The chromosomal anomaly in Apert’s syndrome, on the, has been demonstrated to involve a missense substitution in fibroblast growth factor receptor-2 at two specific amino acid positions on chromosome 10q (Ser252Trp and Pro253Arg) in almost all cases. Several studies have demonstrated that while less common than the serine substitution, the proline substitution may be associated with more severe hand deformities.⁴
• The estimated incidence of Apert’s syndrome is one per 65,000-100,000 live births.⁴
• Apert’s syndrome occurs with equal frequency among males and females subjects, and has been linked to elevated paternal age. The highest prevalence has been found in Asian populations, and lowest prevalence among Hispanics.⁴

Instructions

1. Obtain an accurate and complete patient history.
2. Perform a thorough physical examination of the entire body, with a particular focus on the patient’s hands.
3. Note if syndactyly is present, and if so, its degree and involvement of the digits and web spaces of the hand.

Related Signs and Tests

• X-ray
• Genetic testing

Diagnostic Performance Characteristics

• Upton’s classification system includes three types based on the degree of syndactyly:
  • Type I (spade hand): the thumb is separated from the index finger by a shallow web space, the syndactyly is simple in the fourth interdigital space, and the transverse metacarpal arch is normal
  • Type II (spoon hand): there is partial or complete simple syndactyly of the first web space, the simple syndactyly in the fourth interdigital space is usually complete, the border digits are in marked rotation, and the palm is concave 
  • Type III (rosebud hand): there is complex syndactyly with distal synostosis between the thumb and index finger, and a broad, conjoined nail overlies the bony fusion among the thumb, index, long, and ring fingers; the little finger is usually not included in the osseous union but is joined in a complete, tight, simple syndactyly⁴

• A positive result occurs when the clinician observes syndactyly of the hand(s) that can be classified according to Upton’s system, as well as other craniofacial abnormalities.

• A negative result occurs when the clinician does not observe any signs of syndactyly in the patient’s hands.i.e. the hands are normal.

• Most children with Apert’s syndrome are referred to major craniofacial centers for treatment, where they typically focus on the calvarial and midfacial anomalies and relegate management of the hands and feet to secondary status. Consequently, these children usually undergo multiple small procedures on their hands, which take place between procedures scheduled by the craniofacial team.⁴

1. Raposo-Amaral, CE, Denadai, R, Furlan, P, et al. Treatment of Apert Hand Syndrome: Strategies for Achieving a Five-Digit Hand. Plast Reconstr Surg 2018;142(4):972-982.PMID: 29994846
2. Guero, SJ. Algorithm for treatment of apert hand. Tech Hand Up Extrem Surg 2005;9(3):126-33. PMID: 16175115
3. Oishi, SN and Ezaki, M. Reconstruction of the thumb in Apert syndrome. Tech Hand Up Extrem Surg 2010;14(2):100-3.PMID: 20526163
4. Fearon, JA. Treatment of the hands and feet in Apert syndrome: an evolution in management. Plast Reconstr Surg 2003;112(1):1-12. PMID: 12832871