Polycystic disease of kidney and liver presenting in childhood.

In congenital cystic malformations of the kidney, as in other groups of disorders, the accuracy of genetic counselling depends upon exact diagnosis. This requires the breakdown of the main heterogeneous group into specific entities, each of which is homogeneous from the genetic viewpoint and therefore carries a predictable recurrence risk within the family. It is particularly important to recog- nize the group of 'wholly genetically determined' conditions, those due to chromosomal and single gene mutations, since these may be associated with high risks for sibs or children of index patients.