PAX2 Expression in Renal Dysplasia

ABSTRACT

BACKGROUND: Renal dysplasia is the abnormal development of the kidney. The condition is usually detected in childhood along with other urinary tract anomalies, but can remain unnoticed until adulthood. It was recently reported that a PAX2 gene mutation plays a major role in the development of renal dysplasia. The aim of this study was to examine the expression of PAX2 in dysplastic kidneys of children and adults. METHODS: A total of 30 cases diagnosed with renal dysplasia after a nephrectomy were examined. PAX2 expression was evaluated using immunohistochemistry. Apoptosis was detected using an Apop Tag detection kit. RESULTS: In the dysplastic kidneys, there was strong PAX2 expression in the epithelia of the primitive ducts in both children and adults, but the degree was significantly lower in adults (p=0.007). However, the mesenchyme surrounding the primitive ducts of children showed stronger staining for the smooth muscle actin antibody and trichrome than the adults. The apoptosis index was significantly higher in the primitive duct epithelia than in the surrounding normal collecting duct epithelia (p=0.000). CONCLUSIONS: PAX2 is overexpressed in the primitive ducts of renal dysplasia, which is sustained until adulthood and is associated with increased apoptosis. However, a decrease in PAX2 expression in the dysplastic epithelia and mesenchymal cuff of adults suggest a gradual regression of the dysplastic elements with time.