Medullary cystic disease and juvenile nephronophthisis in separate members of the same family.

The clinical and pathological findings in three sibs dying in renal failure at 9, 15, and 21 years of age respectively are presented. The three sibs showed a similar clinical presentation with an insidious onset of azotaemia without hypertension in association with obligatory dilute urine virtually free of albumin and formed elements. There was renal osteodystrophy in all cases with tertiary hyperparathyroidism in one case. Necropsies were performed on the boy dying at 9 years of age and the girl dying at 21 years of age. In the former the renal histology most closely corresponded to that described in juvenile nephronophthisis while in the latter the appearances were those of medullary cystic disease. We hence affirm that familial juvenile nephronophthisis and medullary cystic disease are basically the same disease and suggest that the development of cysts may be a secondary process, possibly consequent upon interstitial fibrosis and basement membrane thickening, becoming more pronounced with length of survival. The diagnosis in life may be suggested by the familial incidence and characteristic clinical presentation supported by renal biopsy.