Detection of WT1 mRNA in urine from patients with kidney diseases

Detachment of glomerular epithelial cells (GEC) from glomerular basement membrane (GBM) could account for a part of the pathogenic mechanism of proteinuria seen in primary and secondary renal diseases. The Wilms' tumour suppresser gene (WT1) is strictly expressed in GEC in the adult kidney. Mutations of WT1 gene have been implicated in progressive renal damage. Utilizing nested RT-PCR we detected mRNA of WT1 in the urine of patients with renal diseases. Seven of 20 (35%) chronic glomerulonephritis (CGN), eight of 20 (40%) diabetes mellitus (DM) with proteinuria, and two of 24 (8.3%) rheumatic diseases were WT1 positive. Interestingly, only one of 51 (2%) DM without proteinuria was WT1 positive. None of the healthy volunteers or cystitis patients were WT1 positive. This is the first report describing the detection of endogenous WT1 mRNA, an important gene in progressive renal failure, from patients' urine. This technique could be a powerful tool in the search for information about glomerular damage in clinical settings as well as for WT1 mutations or isoform imbalance at the research level without renal biopsy.