Syndactyly type 3

Alternate names

SDTY3; Syndactyly of the ring and little finger; Syndactyly of fingers four and five; Ring and little finger syndactyly

Definition

Syndactyly type 3 (SD3) is a limb abnormality present at birth that is characterized by complete fusion of the 4th and 5th fingers on both hands.

Cause

• SD3 is caused by mutations in the GJA1 gene, which has also been implicated in a condition called oculodentodigital dysplasia.
• The GJA1 gene provides instructions for making a protein called connexin 43, which is one of 21 connexin proteins.
• Connexins play a role in cell-to-cell communication by forming channels, or gap junctions, between cells.
• Gap junctions allow for the transport of nutrients, charged particles (ions), and other small molecules that carry necessary communication signals between cells.
• In addition, connexin 43 attaches (binds) several signaling molecules that can relay communication signals inside the cell.
• Connexin 43 is found in many tissues such as the eyes, skin, bone, ears, heart, and brain, and it plays a role in their normal development and function.

Inheritance

Autosomal dominant pattern, a 50/50 chance.

SD3 is inherited in an autosomal dominant manner.

Signs and symptoms

It is characterized by complete fusion of the 4th and 5th fingers on both hands. In most cases only the soft tissue is fused, but in some cases the bones of the fingers (distal phalanges) are fused.

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

• Finger syndactyly

30%-79% of people have these symptoms

• Camptodactyly of finger(Permanent flexion of the finger)

5%-29% of people have these symptoms

• Short toe(Short toes)

Diagnosis

An infant with webbing may have other symptoms that together may be signs of one syndrome or condition. That condition is diagnosed based on a family history, medical history, and physical exam. The following tests may be done:

• Chromosome studies
• Lab tests to check for certain proteins (enzymes) and metabolic problems
• X-rays

Treatment

Surgery may be done to separate the fingers.

NIH genetic and rare disease info

• NIH info on Syndactyly type 3

Syndactyly type 3 is a rare disease.

Syndactyly type 3 Resources
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