What are the other Names for this Condition? (Also known as/Synonyms)

• Ring and Little Finger Syndactyly
• Syndactyly of Fingers Four and Five
• Syndactyly of the Ring and Little Finger

What is Syndactyly Type 3? (Definition/Background Information)

• 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
• In most cases only the soft tissue is fused, but in some cases the bones of the fingers (distal phalanges) are fused
• There is evidence that SD3 is caused by mutations in the GJA1 gene, which has also been implicated in a condition called oculodentodigital dysplasia. SD3 is the characteristic digital abnormality in this condition. SD3 is inherited in an autosomal dominant manner
• Syndactyly Type 3 has been shown to be inherited in an autosomal dominant manner. This means that having only one mutated copy of the causative gene is sufficient to cause the condition

(Source: Syndactyly Type 3; Genetic and Rare Disease Information Center (GARD) of National Center for Advancing Translational Science (NCATS), USA.)

Who gets Syndactyly Type 3? (Age and Sex Distribution)

• Syndactyly Type 3 is a rare inherited disorder involving the fingers. The onset of symptoms may occur at birth or in infancy
• Both males and females may be born with this disorder
• Worldwide, individuals of all races and ethnicities may be affected

What are the Risk Factors for Syndactyly Type 3? (Predisposing Factors)

• A positive family history may be an important risk factor, since Syndactyly Type 3 can be inherited
• Currently, no other risk factors have been clearly identified for Syndactyly Type 3

It is important to note that having a risk factor does not mean that one will get the condition. A risk factor increases one’s chances of getting a condition compared to an individual without the risk factors. Some risk factors are more important than others.

Also, not having a risk factor does not mean that an individual will not get the condition. It is always important to discuss the effect of risk factors with your healthcare provider.

What are the Causes of Syndactyly Type 3? (Etiology)

• Syndactyly Type 3 may be caused by mutations(s) in the GJA1 gene
• The condition is inherited in an autosomal dominant manner

Autosomal dominant inheritance: Autosomal dominant conditions are traits or disorders that are present when only one copy of the mutation is inherited on a non-sex chromosome. In these types of conditions, the individual has one normal copy and one mutant copy of the gene. The abnormal gene dominates, masking the effects of the correctly function gene. If an individual has an autosomal dominant condition, the chance of passing the abnormal gene on to their offspring is 50%. Children, who do not inherit the abnormal gene, will not develop the condition or pass it on to their offspring.

What are the Signs and Symptoms of Syndactyly Type 3?

The signs and symptoms of Syndactyly Type 1 may include:

• 4-5 finger syndactyly
• Absent middle phalanx of 5th finger
• Short 5th finger

Based on the frequency of symptoms observed, the following information may be noted:

• Very frequently present symptoms in 80-99% of the cases include finger syndactyly
• Frequently present symptoms in 30-79% of the cases include camptodactyly of finger
• Occasionally present symptoms in 5-29% of the cases include short toe

(Source: Syndactyly Type 3; Genetic and Rare Disease Information Center (GARD) of National Center for Advancing Translational Science (NCATS), USA.)

How is Syndactyly Type 3 Diagnosed?

Syndactyly Type 3 is diagnosed on the basis of the following information:

• Complete physical examination
• Thorough medical history evaluation
• Assessment of signs and symptoms
• Laboratory tests
• Imaging studies
• Biopsy studies, if necessary

Many clinical conditions may have similar signs and symptoms. Your healthcare provider may perform additional tests to rule out other clinical conditions to arrive at a definitive diagnosis.

What are the possible Complications of Syndactyly Type 3?

The complications of Syndactyly Type 3 may include:

• Impaired functioning of hands
• Failure of surgery to result in stable, functional and mobile fingers

Complications may occur with or without treatment, and in some cases, due to treatment also.

How is Syndactyly Type 3 Treated?

There is no cure for Syndactyly Type 3, since it is a genetic condition.

• The treatment is usually given to manage the signs and symptoms and any complication that develops. This may be achieved by surgical separation of the joined fingers
• The separation of fused fingers may require multiple surgeries, if the fusion is not limited to the soft tissue, but involves the bones

How can Syndactyly Type 3 be Prevented?

Syndactyly Type 3 may not be preventable, since it is a genetic disorder.

• If there is a family history of the condition, then genetic counseling will help assess risks, before planning for a child
• Active research is currently being performed to explore the possibilities for treatment and prevention of inherited and acquired genetic disorders

Regular medical screening at periodic intervals with tests and physical examinations are recommended.

What is the Prognosis of Syndactyly Type 3? (Outcomes/Resolutions)

• The prognosis of Syndactyly Type 3 is dependent upon the severity of the signs and symptoms and associated complications, if any
• In some cases, surgical separation of the joined fingers may not result in fully functional fingers, and compromise the function of an affected individual’s hands

Additional and Relevant Useful Information for Syndactyly Type 3:

The following DoveMed website link is a useful resource for additional information:

http://www.dovemed.com/diseases-conditions/rare-disorders/