Renal findings in 40 individuals with Williams syndrome.

We tabulated the frequency of renal abnormalities in 40 Williams syndrome individuals presenting for medical and/or developmental assessment to a multi-disciplinary Williams syndrome program. The average age at time of assessment was 7 2/12 years. Seven individuals (7/40 = 18%) had abnormalities detected, including nephrocalcinosis = 2; marked asymmetry in kidney size = 2; small kidneys = 1; solitary kidney = 1; and pelvic kidney = 1. Renal function was also assessed. Two individuals had evidence of renal dysfunction, one secondary to nephrocalcinosis and the second due to hypercalcemia and interstitial nephritis of unclear pathogenesis. We examined the frequency of renal artery stenosis in 9 individuals who underwent abdominal angiography during cardiac catheterization. We found unilateral or bilateral mild renal artery narrowing in 4 individuals and normal renal arteries in the remaining 5. Persistent hypertension occurred in only 2 individuals and did not correlate with renal artery status. We conclude that intrinsic renal anomalies, as well as problems secondary to hypercalcemia, occur with sufficient frequency to warrant baseline renal screening in all individuals with Williams syndrome.