Crossed polysyndactyly

Crossed polysyndactyly is a rare genetic disorder characterized by the combination of polysyndactyly (the presence of extra fingers or toes) and its manifestation across both hands and feet in a crossed manner. This means that if the condition affects the left hand, it will also affect the right foot, or vice versa. The condition is a subtype of syndactyly, which refers to the fusion of digits, and polydactyly, the condition of having more than the usual number of digits.

Causes

Crossed polysyndactyly is primarily caused by genetic mutations. The exact genes involved can vary, but mutations in the gene GLI3 are often implicated. These mutations are inherited in an Autosomal dominant manner, meaning only one copy of the altered gene in each cell is sufficient to cause the disorder. However, cases have been reported where the condition appears without a known family history, suggesting the possibility of new mutations or a more complex genetic mechanism.

Symptoms

Individuals with crossed polysyndactyly typically present with:

• Extra digits on one hand and the opposite foot
• Possible fusion of the extra digits to other digits
• Varied functionality of the affected digits, ranging from fully functional to purely cosmetic

The severity and presentation can vary widely among affected individuals. In some cases, the extra digits are fully formed and functional, while in others, they may be rudimentary.

Diagnosis

Diagnosis of crossed polysyndactyly involves a physical examination and a detailed family history. Imaging tests, such as X-rays, can be used to assess the extent of the condition, including bone structure and the presence of any fused digits. Genetic testing may also be recommended to identify specific mutations, especially in families with a history of the condition.

Treatment

Treatment for crossed polysyndactyly is highly individualized and may include:

• Surgical removal of extra digits, especially if they interfere with function
• Reconstruction of fused digits to improve functionality and appearance
• Physical therapy to enhance mobility and function of the affected digits

The timing and approach to surgery depend on the severity of the condition and the overall health of the individual. Early intervention is often recommended to ensure the best possible outcome.

Prognosis

The prognosis for individuals with crossed polysyndactyly is generally good, especially with early and appropriate treatment. Surgical interventions can significantly improve the functionality and appearance of the hands and feet, allowing individuals to lead normal, active lives.