biomed

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Polydactyly is the most commonly observed congenital digital anomaly of the hands and feet appearing in 1 in every 500 live births. The condition is characterized by an abnormal amount of digits per hand in which the extra digits may develop bilaterally, or it may occur on both or just one hand, foot, or some other combination. Usually the extra digits that develop are either small pieces of soft tissue or fully formed in appearance. It is noted that in around 80% to 90% of cases involve the peripheral digits, although it is possible that all digits may be affected. Depending on the location of the extra digit, polydactyly can be further classified into three types: pre-, post-, and central axial forms. Polydactyly can occur as an isolated disorder (non-syndromic) or alongside other symptoms or disease. Isolated polydactyly is typically caused by the inheritance of an autosomal dominant gene mutation, meaning the cause is not due to a multifactorial trait. However, most cases of polydactylism are linked to specific syndromes that cause congenital anomalies through a variety of gene mutations.
Genetic research has linked the cause of two types of polydactylism, post-axial and pre-axial, to several gene mutations. One particular example is a frameshift mutation in the GLI3 gene on chromosome 7. GLI3 stands for GLI family zinc finger 3 and it is a transcription factor that is vital for proper early development, since it plays a role in the patterning of tissues and organs during embryonic development. Therefore, many congenital anomalies, such as polydactyly, can be linked to the improper expression of this gene.
Post-axial polydactyly (PAP) is characterized by the development of an extra digit adjacent to the pinky finger or toe...

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... at the base of the pedicle. This would clearly be preferable to performing surgery, but may be more applicable in cases of type B than type A polydactyly. Of a total of 21 cases which were examined, this procedure resulted in a slight complication in only one case, where the digit had to be removed surgically due to failure of removal by suture ligation. The only real side effect of this simple treatment is that there was found to be a small bump remaining at the site in 43 percent of cases.
Although there has been some work into the genetic basis of polydactyly, advances in examination of the human genome may create a better understanding of the condition in the future. A large amount of the work done so far has been focused on animal models, and there is still room for further work to discover the genetic basis of the different types of polydactyly in humans.

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