 Primary Hyperoxaluria type 2 is caused by any one of several mutations to the GRHPR gene and results in the accumulation of calcium oxalate in the kidneys, bones, and many other organs.The mutations to GRHPR prevent it from converting glyoxylate to glycolate, leading to a build-up of glyoxylate.This excess glyoxylate is then oxidized by lactate dehydrogenase to produce the oxalate that is characteristic of hyperoxaluria.