Susceptibility to vesicoureteral reflux in Japanese is linked to HLA-DR antigen

A genome scan in affected sib-pairs with familial vesicoureteral reflux identifies a locus on chromosome 5

The basis for vesicoureteral reflux (VUR) is considered to be primarily genetic, with a 30-50% incidence of VUR in first-degree relatives of patients. The search for the causative gene or genes has been elusive, likely because of VUR being genetically heterogeneous with complex inheritance patterns. In this study, a genome-wide analysis of VUR with high-density single nucleotide polymorphisms was conducted with the aim of identifying susceptibility loci for VUR in 98 families with two or more affected children. Using the affected sib-pair method of analysis in 150 sib-pairs, we identified a genome-wide statistically significant linkage peak with an LOD score greater than 4 on chromosome 5 and two linkage peaks with LOD scores greater than 3.6 on chromosomes 13 and 18 were identified in these 98 families. These results suggested that multiple genes are likely to contribute to the formation of VUR phenotype. Further mapping of these linkage peaks may help identify the causative genes.

Vesicoureteral reflux

Vesicoureteral reflux (VUR), the retrograde flow of urine from the bladder toward the kidney, is common in young children. About 30% of children with urinary tract infections will be diagnosed with VUR after a voiding cystourethrogram. For most, VUR will resolve spontaneously; 20% to 30% will have further infections, but few will experience long-term renal sequelae. Developmentally, VUR arises from disruption of complex signaling pathways and cellular differentiation. These mechanisms are probably genetically programmed but may be influenced by environmental exposures. Phenotypic expression of VUR is variable, ranging from asymptomatic forms to severe renal parenchymal disease and end-stage disease. VUR is often familial but is genetically heterogeneous with variability in mode of inheritance and in which gene, or the number of genes, that are involved. Numerous genetic studies that explore associations with VUR are available. The relative utility of these for understanding the genetics of VUR is often limited because of small sample size, poor methodology, and a diverse spectrum of patients. Much, if not all, of the renal parenchymal damage associated with end-stage disease is likely to be congenital, which limits the opportunity for intervention to familial cases where risk prediction may be available. Management of children with VUR remains controversial because there is no strong supportive evidence that prophylactic antibiotics or surgical intervention improve outcomes. Furthermore, well-designed genetic epidemiological studies focusing on the severe end of the VUR phenotype may help define the causal pathway and identify modifiable or disease predictive factors.

Linkage study of 14 candidate genes and loci in four large Dutch families with vesico-ureteral reflux

Vesico-ureteral reflux (VUR) is a major contributing factor to end-stage renal disease in paediatric patients. Primary VUR is a familial disorder, but little is known about its genetic causes. To investigate the involvement of 12 functional candidate genes and two reported loci in VUR, we performed a linkage study in four large, Dutch, multi-generational families with multiple affected individuals. We were unable to detect linkage to any of the genes and loci and could exclude the GDNF, RET, SLIT2, SPRY1, PAX2, AGTR2, UPK1A and UPK3A genes and the 1p13 and 20p13 loci from linkage to VUR. Our results provide further evidence that there appears to be genetic heterogeneity in VUR.