Split Hand or Foot Malformation (SHFM)
Description
Split hand/foot malformation (SHFM), also known as ectrodactyly, is a congenital condition characterized by malformations of the hands and/or feet. This condition affects the development of the bones and tissues in these extremities, leading to various degrees of splitting or missing fingers and toes. SHFM can range in severity from mild to severe, and individuals with the condition may experience functional limitations and social challenges. This blog will delve into the details of SHFM, exploring its causes, signs and symptoms, diagnosis, management strategies, and resources for individuals living with this condition.
Genes Involved
Several genes have been linked to SHFM, including:
- TP63: Mutations in this gene are associated with a variety of developmental disorders, including SHFM.
- DLX5: This gene plays a role in limb development and mutations can lead to SHFM.
- WNT10B: Mutations in this gene are linked to various skeletal abnormalities, including SHFM.
- HOXD13: This gene is involved in the development of the hands and feet, and mutations can cause SHFM.
- GLI3: This gene regulates limb development, and mutations can lead to SHFM.
Further research is ongoing to understand the complex genetic mechanisms underlying SHFM and identify additional genes involved.
Recognizing the Signs and Symptoms
The most common sign of SHFM is the presence of a split hand or foot, with missing or partially formed fingers or toes. Other symptoms may include:
- Missing or fused fingers or toes: This can range from a single digit to all fingers or toes.
- Shortening of fingers or toes: The remaining digits may be shorter than normal.
- Webbing between fingers or toes: This occurs when the digits are partially joined.
- Deformities of the hands or feet: This can include unusual angles or positions of the digits.
- Limited mobility in the hands and/or feet: This can affect dexterity and grip strength.
The specific symptoms of SHFM vary depending on the severity of the condition. Some individuals may have only minor malformations, while others may have more significant impairments.
Causes
The exact cause of SHFM is not fully understood, but it is believed to be a combination of genetic and environmental factors.
- Genetic factors: Mutations in certain genes involved in limb development can increase the risk of SHFM. These mutations can be inherited from a parent or occur spontaneously.
- Environmental factors: While less understood, some environmental factors may also play a role in SHFM. These may include exposure to teratogens (substances that can cause birth defects) during pregnancy or other unknown factors.
The precise interplay of these factors is still being investigated.
Inheritance/recurrence risk
The inheritance pattern of SHFM can vary depending on the specific gene involved. In some cases, it can be inherited in an autosomal dominant pattern, meaning that a single copy of the mutated gene from one parent is sufficient to cause the condition. In other cases, it may follow an autosomal recessive pattern, where two copies of the mutated gene, one from each parent, are necessary for the condition to develop.
The risk of recurrence depends on the inheritance pattern and the specific gene involved. If both parents carry the mutated gene, there is a 25% chance of their child inheriting SHFM. However, in many cases, the cause is unknown, and the risk of recurrence is difficult to predict.
