syndactyly type 5

Syndactyly Type 5 (SD5) Description

Syndactyly type 5, also known as Dowd type syndactyly, is a rare congenital limb malformation characterized by the fusion of adjacent digits. Specifically, it involves the postaxial syndactyly of hands and feet, associated with metacarpal and metatarsal fusion of the fourth and fifth digits.

• Hands: The condition affects the hands, causing the fourth and fifth fingers to be fused together.
• Feet: Similarly, in the feet, the fourth and fifth toes are affected, resulting in their fusion.
• Soft tissue syndactyly: In some cases, soft tissue syndactyly may also be present, involving the third and fourth fingers and the second and third toes.

Syndactyly type 5 is a rare condition, with less than ten reports described in the literature. It is inherited in an autosomal dominant manner, meaning that a single copy of the mutated gene is enough to cause the condition.

References:

• [1] Syndactyly type V (Dowd type; fusion of 4/5 metacarpals) - A hallmark of this type is the fusion of fourth and fifth metacarpals.
• [3] A very rare congenital limb malformation with characteristics of postaxial syndactyly of hands and feet, associated with metacarpal and metatarsal fusion of fourth and fifth digits.
• [8] Syndactyly type 5 (SD5) is a very rare congenital limb malformation characterized by postaxial syndactyly of hands and feet, associated with metacarpal and ...
• [9] Syndactyly type 5 (SD5)​​ SD5 (MIM 186300) is a rare limb anomaly, also known as the Dowd type syndactyly.

Symptoms of Syndactyly Type 5

Syndactyly type 5, also known as soft tissue syndactyly of the 3rd and 4th fingers and the 2nd and 3rd toes associated with metacarpal and metatarsal fusion of the 4th and 5th digits, is a rare non-syndromic subtype of syndactyly.

• Soft tissue webbing: The 3rd and 4th fingers and the 2nd and 3rd toes are joined by soft tissue, creating a webbed appearance [12].
• Metacarpal and metatarsal fusion: The 4th and 5th digits have metacarpal and metatarsal fusion, which can further restrict finger and toe movement.
• Limited mobility: The fused fingers and toes may not move well, affecting overall hand and foot function [1].

It's essential to note that syndactyly type 5 is a rare condition, and its symptoms may vary from person to person. A proper medical evaluation by a healthcare professional is necessary for an accurate diagnosis and treatment plan.

References: [12] - A rare non-syndromic syndactyly characterized by soft tissue syndactyly of the 3rd and 4th fingers and the 2nd and 3rd toes associated with metacarpal and ... [1] - Children with syndactyly are born with 2 or more fingers or toes that are joined. The joined digits may look webbed, and they may not move well. For some ...

Diagnostic Tests for Syndactyly Type 5

Syndactyly type 5 (SD5) is a rare congenital limb malformation that requires accurate and proper diagnosis to determine the best course of treatment. The following diagnostic tests are commonly used to diagnose SD5:

• Clinical Evaluation: A thorough clinical evaluation by a qualified healthcare professional, such as an orthopedic surgeon or geneticist, is essential for diagnosing SD5 [5].
• Radiography: Radiographic imaging may be necessary to confirm the diagnosis and assess the extent of the limb malformation [5].
• Surgical Release: Surgical release of the affected digits at 6 months of age is a common treatment approach for SD5 [5].

In addition to these tests, genetic analysis may also be performed to identify any underlying genetic mutations that may contribute to the development of SD5. This can include:

• Sequence Analysis: DNA sequence analysis can help identify specific mutations in genes such as HOXD13 [4].
• Deletion/Duplication Analysis: MLPA (Methylation-Sensitive PCR) has greater than 99% sensitivity for detecting deletion and duplication variants, which may be relevant in the case of SD5 [2].
• Cytogenetic/Fluorescent In Situ Hybridization (FISH): This test can help identify any chromosomal abnormalities that may contribute to the development of SD5 [7].

A 21-gene panel that includes assessment of non-coding variants is also ideal for patients with brachydactyly and/or syndactyly, including SD5 [8].

Syndactyly type 5 (SD5) is a rare form of syndactyly, which involves the fusion of the fourth and fifth metacarpals. To determine the differential diagnosis for SD5, let's consider the following possibilities:

• Other types of syndactyly: While SD5 is distinct from other types of syndactyly, such as SD1 (complete cutaneous syndactyly) or SD7 (partial cutaneous syndactyly), it's essential to rule out these conditions through a thorough clinical examination and radiographic evaluation [3].
• Polydactyly: Polydactyly is a congenital anomaly characterized by the presence of extra fingers or toes. In some cases, polydactyly can be associated with syndactyly, including SD5 [7].
• Cleft hands: Cleft hands are a rare congenital anomaly that involves a cleft in the hand, which can be associated with syndactyly, including SD5 [4].
• Ring constrictions: Ring constrictions are a type of limb malformation that can be associated with syndactyly, including SD5 [4].

It's also worth noting that syndactyly can be an isolated finding or it can be found in association with other abnormalities. Therefore, a comprehensive evaluation is necessary to determine the underlying cause and differential diagnosis for SD5.

References:

• [3] Syndactyly type 5 (SD5) is another rare form of syndactyly. This syndactyly is usually complete and involves fusion of both cutaneous and bony tissue.
• [4] Syndactyly can be an isolated finding, or it can be found in association with other abnormalities (eg, polydactyly, cleft hands, ring constrictions).
• [7] The syndactyly is described as complete, affecting the fingers of both hands, with associated polydactyly, generally involving 6 metacarpals and 6 digits.