PAX2 Polymorphisms and Congenital Abnormalities of the Kidney and Urinary Tract in a Brazilian Pediatric Population: Evidence for a Role in Vesicoureteral Reflux

Abstract

Congenital anomalies of the kidney and urinary tract (CAKUT) are common genetic malformations. Since the PAX2 gene has a role in kidney organogenesis, this study investigated the association of PAX2 gene polymorphisms with CAKUT in general and with specific phenotypes of CAKUT in a Brazilian pediatric population. This study included 241 individuals with antenatal hydronephrosis and 259 healthy controls. For genotyping and allelic discrimination we used the probes to rs2077642, rs4244341, rs6421335, rs11190698, and rs11190693. No statistical differences in allele and genotype frequencies were observed for the single nucleotide polymorphism (SNP) rs11190693. At the SNPs rs4244341 and rs11190698, the frequencies of the ancestral alleles were significantly higher among CAKUT patients (rs4244341 allele G: 0.86 vs. 0.78; rs11190698 allele A: 0.85 vs. 0.79). At the SNP rs4244341, the genotype GG was increased in CAKUT group (0.72 vs. 0.61, P = 0.013), while the TT was higher in controls (0.01 vs. 0.05, P = 0.001). At the SNP rs11190698, the genotype CC was increased in controls (0.02 vs. 0.06, P = 0.01). The most frequent CAKUT phenotypes were vesicoureteral reflux (VUR), multicystic dysplastic kidney (MCDK), and ureteropelvic junction obstruction (UPJO). In patients with VUR, the frequencies of the monozygotic ancestral alleles decreased at the SNP rs11190693 (AA 0.13 vs. 0.26, P = 0.04) and increased at the SNP rs4244341 (GG 0.77 vs. 0.61, P = 0.03). No statistical differences were detected between controls and patients with UPJO and with MCDK for all SNPs. The PAX2 gene seems to be involved with the pathogenesis of VUR in our sample.