Medullary sponge kidney associated with primary distal renal tubular acidosis and mutations of the H+-ATPase genes.

Methods and results. We report two patients presenting with dRTA, late sensorineural hearing loss and MSK, in whom molecular investigations demonstrated the presence of mutations of the H+ proton pump ATP6V1B1 and ATP6V0A4 genes. Conclusions. These observations, including a previous description of a similar case in the literature, indicate that MSK could be a consequence of the proton pump defect, thus can potentially provide new insights into the pathogenesis of MSK.