A familial syndrome of aniridia and absence of the patella.

This is the first report of a syndrome of aniridia and aplasia of the patella. The origin of the defect arises spontaneously in the grandmother of the proband and must be assumed to be a de novo mutation. There is no associated chromosomal abnormality or overt biochemical or other somatic defect. This is an extremely rare mutation exhibiting a dominant autosomal form of inheritance. The gene for aniridia is a dominant gene whose penetrance here is 100%. The combination of aniridia and bone malformations in general is very rare. This linked defect probably represents one of the most rare of human genetic abnormalities. The penetrance of the combined abnormality seems to follow that of the more well-known aniridia gene.