Polycystic kidney disease re-evaluated: a population-based study.

A genetic register of all known cases of autosomal dominant polycystic kidney disease occurring in South and Mid-Wales has been established. In a population of 2.1 million, 209 families with affected members were identified, 303 of whom are currently alive, 70 on renal replacement therapy. An additional 551 cases would be predicted amongst family members at 50 per cent and 25 per cent risk, giving an apparent prevalence of 1:2459 in the general population. Five possible new mutations were seen where adults with phenotypic autosomal dominant polycystic kidney disease had both parents alive, age greater than 55 years with no cysts visible on ultrasound. The take-on rate for renal replacement therapy increased during 1970-79 but has apparently reached a plateau of 4.8 cases per million population per year over the last 8 years, despite a rapidly increasing acceptance of uraemic patients as a whole (72/10(6)/year in 1988-89). Considerably more patients with autosomal dominant polycystic kidney disease aged over 50 years were started on treatment in 1980-89 than in 1970-79, but the survival overall improved with time. All cases of autosomal dominant polycystic kidney disease reaching end-stage renal disease are now being treated, but the apparent clinical prevalence of this condition in our region is less than half the supposed gene frequency, suggesting that undiagnosed cases have a benign prognosis.