EXOME SEQUENCING IN MEDULLARY SPONGE KIDNEY

Medullary sponge kidney is a rare, underdiagnosed renal pathology, characterized by precalyceal dilatation of the renal tubes associated with active and recurrent stone disease with nephrocalcinosis, hypercalciuria and tubular dysfunction with, for example, acidification and urinary concentration defects.

The pathophysiology is poorly understood The prevalence and etiopathogenesis of the disease is not known Medullary sponge kidney is often characterized as a congenital pathology with delayed expression due to reported cases occurring in early childhood and associations with other congenital renal and extra-renal malformative pathologies, such as Wilms tumors, horseshoe kidney, contralateral renal hypoplasia, Beckwith-Wiedemann syndrome, Caroli disease, or congenital hepatic fibrosis, for example. However, no clear demonstration of the congenital nature has been established so far, and it is considered a sporadic disease.

However familial cases have been reported with an autosomal dominant mode.

The pathophysiology may involve disruptions in renal organogenesis, which depends on reciprocal inductive interactions necessary to coordinate nephrogenesis between the ureteric bud and the metanephric blastema during the 5th week of embryonic development. Some authors suggested that the GDNF and RET genes may be involved in the physiopathology of the disease.

For instance 12% of heterozygous patients for rare GDNF variants were identified in an Italian cohort of 57 medullary sponge kidney patients.

Other genes have been suggested to be involved in the pathophysiology based on reported cases, with no direct relationship demonstrated and their role remain putative Medullary sponge kidney disease is a debilitating condition, with the main symptoms being recurrent kidney stones and urinary infections.

Additional data are needed to determine the involvement of genetic anomalies in the pathophysiology of the condition.

The aim of the study is to describe the genetic variants identified with exome sequencing in medullary sponge kidney patients, in order to optimize management, especially for familial forms, and therapeutic interventions.