What is a genetic disease that begins with the letter "J"?

Jackson-Weiss Syndrome is a hereditary disease that
affects the skull, face, and feet. It is inherited in an autosomal dominant
manner.

One characteristic of JWS is an unusual skull
shape. This leads to an abnormally shaped face, usually a small midface. The toes are
also very wide and webbed between the second and third toe. Some of the bones may be
fused together as well.

The reason for the abnormally
shaped skull is due to the fact that portions of the skull fuse together too
early.

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Jackson-Weiss syndrome is inherited in an
autosomal dominant manner. This means that possession of only one copy of the defective
gene is enough to cause disease. When a parent has Jackson-Weiss syndrome each of his or
her children have a 50% chance to inherit the disease-causing mutation. JWS is believed
to have a high rate of penetrance. This means that almost all people who inherit the
altered gene will manifest symptoms. JWS has also occurred spontaneously in babies with
no family history of it or any similar disorder. This is known as a sporadic occurrence.
Most commonly, JWS is associated with changes in
FGFR2.