Brachydactyly type A4

Alternate names

BDA4; Brachydactyly Temtamy type; Temtamy type brachydactyly; Brachymesophalangy II and V

Definition

A rare congenital limb malformation characterized by short middle phalanges of the 2nd and 5th fingers and absence of the middle phalanges of toes 2 to 5. Occasionally, the 4th digit may be affected and manifests with an abnormally shaped middle phalanx which causes radial deviation of the distal phalanx. Other hand/foot malformations, such as syndactyly, polydactyly, reduction defects and symphalangism, may be associated.

Epidemiology

This type is apparently rare. Only few pedigrees were reported.

Cause

• Mutations in the homeobox containing gene (HOXD13) can give rise to limb malformations with variable expressivity and a wide spectrum of clinical manifestations including synpolydactyly and brachydactyies types D and E. .
• Zhao et al. found a link between HOXD13 and two additional limb phenotypes – syndactyly type V and brachydactyly type A4, and suggested the term "HOXD13 limb morphopathies" for the spectrum of limb disorders caused by HOXD13 mutations.

Signs and symptoms

• The main features were brachymesophalangy affecting mainly the 2nd and 5th digits.
• When the 4th digit was affected, it showed an abnormally shaped middle phalanx leading to radial deviation of the distal phalanx.
• The feet also showed absence of middle phalanges of the lateral four toes.
• The propositus had congenital talipes calcaneovalgus.

For most diseases, symptoms will vary from person to person. People with the same disease may not have all the symptoms listed. 80%-99% of people have these symptoms

• Short middle phalanx of the 2nd finger(Short middle bone of index finger)
• Short middle phalanx of the 5th finger(Short middle bone of the little finger)
• Shortening of all middle phalanges of the toes(Shortening of all the middle bones of the toes)

30%-79% of people have these symptoms

• Short stature(Decreased body height)
• Symphalangism affecting the phalanges of the hand(Fused finger bones of the hand)

5%-29% of people have these symptoms

• Talipes equinovarus(Club feet)

Diagnosis

Clinical evaluation of digits. Radiological examination and pattern profile analysis for the length of the phalanges..

Treatment

• There is no specific management or treatment that is applicable to all forms of brachydactyly. .
• Plastic surgery is only indicated if the brachydactyly affects hand function or for cosmetic reasons, but is typically not needed.
• Physical therapy and ergotherapy may ameliorate hand function.

Prognosis

Prognosis for the brachydactylies is strongly dependent on the nature of the brachydactyly, and may vary from excellent to severely influencing hand function. If brachydactyly forms part of a syndromic entity, prognosis often depends on the nature of the associated anomalies.

NIH genetic and rare disease info

• NIH info on Brachydactyly type A4

Brachydactyly type A4 is a rare disease.

Brachydactyly type A4 Resources
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