Congenital Contractural Arachnodactyly

Congenital contractural arachnodactyly (Beals syndrome) is an autosomal dominant condition caused by FBN2 variants, with crumpled ears, long thin digits, multiple joint contractures and kyphoscoliosis. The cardiac and aortic features seen in Marfan syndrome are uncommon.

Pathophysiology. Fibrillin-2 forms microfibrils of the extracellular matrix, especially in embryonic tissue. Variants, mostly in exons 24 to 35, disrupt microfibril assembly and cause contractures and skeletal changes.

Most cases are inherited, and a severe infantile form with cardiac and gastrointestinal anomalies is rare.

Contractures often improve with age, but scoliosis can progress.

• Crumpled (folded) helix of the ears
• Arachnodactyly and tall, slender build
• Contractures of elbows, knees, hips, fingers and ankles, camptodactyly
• Kyphoscoliosis, often progressive
• Pectus deformity and talipes
• Muscular hypoplasia and hypotonia
• Mitral valve prolapse and, rarely, aortic root dilatation
• Severe infantile form: cardiac defects and gastrointestinal anomalies

• Clinical diagnosis: crumpled ears with arachnodactyly and contractures in a patient with a normal lens position.
• Genetic testing of FBN2, and FBN1 to exclude Marfan syndrome.
• Echocardiography for aortic root and mitral valve.
• Spine radiographs to measure the Cobb angle.
• Eye examination: lens position (ectopia lentis is not typical).
• Family examination for ear and digit findings.

Differential diagnosis.

• Marfan syndrome
• Loeys-Dietz syndrome
• Shprintzen-Goldberg syndrome
• Homocystinuria
• Distal arthrogryposes
• Stickler syndrome

• Contractures: physiotherapy with stretching and serial splinting or casting from infancy. Surgical release is rarely needed, since improvement is common.
• Scoliosis: bracing for curves of about 25 to 40 degrees in a growing child, and spinal fusion for progressive curves over 45 to 50 degrees or those affecting breathing.
• Pectus and foot deformity: orthotics, and surgery when symptomatic or severe.
• Cardiac care: baseline echocardiography. If aortic root dilatation develops, use losartan 25 to 100 mg orally daily (children 0.4 to 1.4 mg/kg daily, maximum 100 mg) or a beta blocker, with echocardiography every 6 to 12 months.
• Hearing and ears: audiological assessment if hearing is a concern. Ear shape does not need treatment.
• Severe infantile form: neonatal cardiac and gastrointestinal care with surgery as needed.
• Genetic counselling: recurrence risk of 50%.

Special groups.

• Children: orthopaedic follow up through growth, with early physiotherapy to prevent fixed deformity.

Monitoring. Spine review every 6 months during growth. Echocardiography at baseline and every 2 to 3 years when normal. Review joint range of motion yearly.

Referral and escalation. Refer to clinical genetics, orthopaedics, physiotherapy and cardiology. Urgent for rapid curve progression, respiratory compromise or aortic dilatation.