Polydactyly and Syndactyly
What is polydactyly?
Polydactyly, a congenital abnormality, is the
presence of more than the normal number of
fingers or toes. the condition is usually
inherited as an autosomal dominant characteristic
and can usually be corected by surgery. If
recommended, the surgery is usually done while
the child is about 1 year of age. Also called
polydactylia, polydactylism or hyperdactyly.
Polydactyly can vary from an unnoticeable
rudimentary finger or toe to fully developed
extra digits. Polydactyly and syndactyly (fusion
of the fingers or toes) can occur simultaneously
when extra digits are fused. This condition is
known as polysyndactyly.
What is syndactyly?
Syndactyly is the webbing or fusing together
of two or more fingers or toes. It varies in
degree of severity from incomplete webbing of the
skin of two digits to complete union of digits
and fusion of the bones and nails. the fusion can
be simple with the digits connected only by skin,
or it can be complicated with shared bones,
nerves, vessels, or nials. Also called
syndactylia or syndactylism.
What are the causes and symptoms?
Polydactyly is due to errors in the process of
fetal development. For example, syndactyly
results from the failure of the programmed cell
death that normally occurs between digits. Most
often these errors are due to genetic defects.
Polydactyly and syndactyly can both occur by
themselves as isolated conditions or in
conjunction with other symptoms as one aspect of
a multi-symptom disease. There are several forms
of isolated syndactyly and several forms of
isolated polydactyly; each of these, where the
genetics is understood, is caused by an autosomal
dominant gene. This means that since the gene is
autosomal (not sex-linked), males and females are
equally likely to inherit the trait. This also
means that since the gene is dominant, children
who have only one parent with the trait have a 50
percent chance of inheriting it. However, people
in the same family carrying the same gene can
have different degrees of polydactyly or
syndactyly.
Polydactyly and syndactyly are also possible
outcomes of a large number of rare inherited and
developmental disorders. One or both of them can
be present in more than 100 different disorders
where they are minor features compared to other
characteristics of these diseases. In some
isolated cases of polydactyly or syndactyly, it
is not possible to determine the cause. Some of
these cases might nevertheless be due to genetic
defects; sometimes there is too little
information to demonstrate a genetic cause. Some
cases might be due external factors like exposure
to toxins or womb anomalies.
Diagnosis
Polydactyly and syndactyly can be diagnosed by
external observation, X-ray, or fetal sonogram.
Treatment
Polydactyly can be corrected by surgical
removal of the extra digit or partial digit.
Syndactyly can also be corrected surgically,
almost always with the addition of a skin graft
from the groin.
Prognosis
The prognosis for isolated polydactyly and
syndactyly is excellent. When polydactyly or
syndactyly are part of a syndrome or group of
medical conditions, the prognosis depends on the
syndrome. Some of these syndromes can be quite
serious.
This information has been designed as a comprehensive and quick reference
guide written by our health care reviewers. The health information written
by our authors is intended to be a supplement to the care provided by your
physician. It is not intended nor implied to be a substitute for
professional medical advice.
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