Renal Cysts and Associated Malformations in Pediatric Autopsy Material

Abstract

Autosomal recessive polycystic kidney disease (ARPKD), also known as infantile polycystic kidney disease (or Potter type I), and autosomal dominant polycystic kidney disease (ADPKD), an adult form of polycystic kidney disease (or Potter type III), are the two main types of genetic polycystic kidney diseases encountered in infants and children. The clinical spectrum of ARPKD is variable, however, it presents mainly in infancy and most affected viable neonates die within the first few hours of extrauterine life. Some of the clinical variability is accounted for by differences in the genotypes responsible for the clinical syndrome of ADPKD. At least three different gene codes for the development of ADPKD have been identified, with loci mapped to chromosome 16 (polycystic kidney disease or PKD1), 1,2 to chromosome 4 (PKD2), 3 and recently a small number of families with ADPKD that are not linked to the PKD1 and PKD2 loci. 4,5 A single ARPKD gene is identified and is linked to chromosome 6. 6 The morphologic criteria applied to make distinctions among the different types of chronic renal disease (CRD) involve the cyst size, number, cyst distribution within the kidney, the site along the nephron from which the cysts arise, and the possible involvement of other organs. CRD may present as a non-syndromal heritable and sporadic form, or as a component of a malformation syndrome. 7 The aim of this study was to determine the relative frequency of the different types of CRD, and to study the frequency of associated extrarenal disorders and congenital malformations. In this report, we emphasize the latter as an important consideration in cases presenting in the neonatal period.