Gonadal mosaicism in pseudoachondroplasia.

We report on a family in which a brother and sister have pseudoachondroplasia and normal parents. The brother married a normal woman, and they have 2 daughters; one of them has typical changes of pseudoachondroplasia, the other is normal. The most likely explanation in this family is gonadal (germinal cell) mosaicism in one of the grandparents. Other reports of possible autosomal recessive pseudoachondroplasia are reviewed. It is likely that gonadal mosaicism is responsible for a small percentage of cases with what appears to be a new mutation for pseudoachondroplasia.