Polysyndactyly type 4

Polysyndactyly type 4 (PSD4), also known as Haas type polysyndactyly, is a rare genetic disorder characterized by the combination of syndactyly (the fusion of digits) and polydactyly (the presence of extra digits) in the hands and feet. This condition is one of several types of polysyndactyly, which vary in their specific features and genetic causes.

Symptoms and Characteristics

Individuals with Polysyndactyly type 4 typically present with both syndactyly, where two or more fingers or toes are fused together, and polydactyly, where extra fingers or toes are present. The severity and specific characteristics of these features can vary widely among affected individuals. In some cases, the extra digits are fully formed and functional, while in others, they may be rudimentary.

Genetics

Polysyndactyly type 4 is believed to be inherited in an autosomal dominant manner, meaning that only one copy of the altered gene in each cell is sufficient to cause the disorder. However, the specific genetic mutations responsible for PSD4 have not been fully identified, and it is possible that multiple genetic factors may contribute to the condition.

Diagnosis

Diagnosis of Polysyndactyly type 4 is primarily based on physical examination and the observation of characteristic symptoms. In some cases, genetic testing may be used to confirm the diagnosis or to differentiate PSD4 from other types of syndactyly and polydactyly. Imaging studies, such as X-rays, can also be helpful in assessing the extent of bone involvement and planning for surgical treatment.

Treatment

Treatment for Polysyndactyly type 4 typically involves surgical intervention to separate fused digits and/or to remove or reconstruct extra digits. The goals of surgery are to improve the function and appearance of the hands and feet, and to address any associated complications. The timing and specific approach to surgery may vary depending on the individual's age, the severity of their condition, and other factors.

Prognosis

The prognosis for individuals with Polysyndactyly type 4 is generally good, especially with early and appropriate surgical treatment. Most affected individuals are able to achieve good functional outcomes and lead normal, active lives.

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