Down's syndrome, renal manifestations

(John Down, 1828 - 1896, English physician). For a general description of the syndrome, see Downs syndrome.

Reduced kidney size is the commonest renal manifestation of Down's syndrome, and is believed to be due to a developmental global reduction in the total number of nephrons. Renal size is decreased by 10 - 15% in patients with Down's syndrome, when compared to age- and weightmatched controls. Glomerular microcysts are common pathological findings in Down's syndrome, but are not usually evident radiologically. However, the incidence of simple cysts is increased, and may represent the macroscopic correlate of glomerular microcysts. Up to 6% of children with Down's syndrome have radiologically detectable simple renal cysts (see cyst renal). Obstructive uropathy has been reported in Down's syndrome, although the exact prevalence and pathogenesis is unclear. However, recognition of the association of obstructive uropathy with Down's syndrome is especially important in perinatal pathology. Obstructive uropathy with or without dysplastic changes of the kidneys may be detected by an ultrasound examination during the second trimester of pregnancy. The characteristic features of Down's syndrome may be subtle at this point in development. Chromosomal analysis should be done in any case of obstructive uropathy or Potter's sequence in a fetus or neonate to rule out Down's syndrome or other chromosomal aberration. Other renal disorders associated with Down's syndrome include horseshoe kidney, duplication of the renal pelvis and ureter, mesangiocapillary glomerulonephritis and cystinuria. Renal involvement in Down's syndrome may be incidental as in any healthy individual. Acute renal failure may follow surgical correction of congenital heart malformations in Down's syndrome. Overall, the prevalence of renal insufficiency does not seem to be higher than in the normal population.

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