Drs. Alexander and Campbell (Pediatrics, 45: 1024) rightly mention the similarity between Medullary Cystic disease and familial juvenile nephronophthisis. It is now clear that the separation of these disorders on the basis of familial occurrence, age of onset, and presence of medullary cysts is not possible.
I, however, disagree with these authors' recommendation to refer to these conditions as "Familial Uremic Medullary Cystic disease." The disorder is not always familial and the cystic changes are not confined to renal medulla.
Familial Juvenile Nephronophthisis
