Polydactyly preaxial type 1

Polydactyly Preaxial Type 1

Polydactyly Preaxial Type 1, also known as thumb duplication or preaxial polydactyly, is a congenital anomaly characterized by the duplication of the thumb. This condition is a type of polydactyly, which refers to the presence of extra digits on the hands or feet. Preaxial polydactyly specifically involves the radial or thumb side of the hand.

Etiology

Polydactyly Preaxial Type 1 is often caused by genetic mutations that affect limb development. It can occur as an isolated condition or as part of a syndrome. Mutations in the GLI3 gene, which plays a crucial role in limb patterning, have been associated with this condition. In some cases, it may be inherited in an autosomal dominant pattern, meaning a single copy of the altered gene in each cell is sufficient to cause the disorder.

Clinical Presentation

Patients with Polydactyly Preaxial Type 1 typically present with a duplicated thumb, which can vary in size and functionality. The duplication may involve only the distal phalanx or extend to include the entire thumb, including the metacarpal bone. The extra digit may be fully functional or may lack normal movement and sensation.

Diagnosis

Diagnosis of Polydactyly Preaxial Type 1 is primarily clinical, based on physical examination of the hand. Imaging studies, such as X-rays, can be used to assess the extent of the duplication and to plan surgical intervention if necessary. Genetic testing may be performed to identify any underlying genetic mutations, especially if the condition is part of a syndrome.

Treatment

The treatment of Polydactyly Preaxial Type 1 often involves surgical intervention to remove the extra digit and reconstruct the thumb. The timing of surgery depends on the severity of the duplication and the presence of any functional impairment. Early intervention is usually recommended to improve hand function and appearance.

Prognosis

The prognosis for individuals with Polydactyly Preaxial Type 1 is generally good, especially when surgical correction is performed early. Most patients achieve good functional and cosmetic outcomes. However, the specific prognosis can vary depending on the complexity of the duplication and the presence of any associated syndromes.

Also see

• Polydactyly
• Syndactyly
• Congenital limb deformities
• GLI3