What is the definition of Split Hand Foot Malformation?
Split hand foot malformation (SHFM) is a type of birth defect that consists of missing digits (fingers and/or toes), a deep cleft down the center of the hand or foot, and fusion of remaining digits. The severity of this condition varies widely among affected individuals. SHFM is sometimes called ectrodactyly; however, this is a nonspecific term used to describe missing digits. SHFM may occur by itself (isolated) or it may be part of a syndrome with abnormalities in other parts of the body. At least six different forms of isolated SHFM have been described. Each type is associated with a different underlying genetic cause. SHFM1 has been linked to chromosome 7, and SHFM2 is linked to the X chromosome. SHFM3 is caused by a duplication of chromosome 10 at position 10q24. Changes (mutations) in the TP63 gene cause SHFM4. SHFM5 is linked to chromosome 2, and SHFM6 is caused by mutations in the WNT10B gene. SHFM may be inherited in an autosomal dominant, autosomal recessive, or X-linked manner.
What are the alternative names for Split Hand Foot Malformation?
What are the causes for Split Hand Foot Malformation?
Split hand foot malformation may occur as an isolated feature or it may be associated with a genetic syndrome. Researchers believe that a large number of mutations can cause split hand foot malformation. A few of which have been identified: FBXW4 and TP63. Most commonly the conditions are passed through families in an autosomal dominant fashion with reduced penetrance. In autosomal dominant inheritance an affected parent would have a 1 in 2 or 50% chance with each pregnancy of passing the genetic defect to his/her offspring. In conditions with “reduced penetrance” a person who inherits the underlying genetic defect, may never develop the condition.
More rarely other forms of inheritance have been reported (e.g., autosomal-recessive, X-linked, chromosome deletions, chromosome duplications).