The urinary system in Down syndrome: a study of 124 autopsy cases.

We examined 124 autopsy cases of Down syndrome for the presence of renal and urinary tract abnormalities. The cases were divided into three groups: (I) fetuses of 16-22 weeks gestation (n = 18), (II) stillborns or newborns who died on the first day of life (n = 9), and (III) Down patients 1 day to 25 years of age (n = 97). Kidney weight was reduced by a mean of 14.4% compared with expected values. Renal hypoplasia, defined as kidney weight less than two-thirds expected, was found in 18 cases. Glomerular microcysts were found in 23 of 97 cases in group III. Focal dilatation of tubules was found in 10, simple cysts in 7, and immature glomeruli deep in the renal cortex in 18 cases. Obstructive uropathy occurred in 2 of 18 (11.1%) in group I, 2 of 9 (22.2%) in group II, and 4 of 97 (4.1%) in group III. Obstructive uropathy with bilateral cystic dysplastic kidneys resulted in Potter's sequence. We suggest that obstructive uropathy is associated with Down syndrome. When severe, it results in Potter's sequence and an early perinatal death. A chromosomal analysis is recommended in any case of obstructive uropathy in the fetal or neonatal period.