Primary hyperoxaluria is a rare genetic inherited disorder that is present at birth. It comes in many forms, of which only two, Type I and Type II, are well characterized. Type I and Type II are autosomal recessive diseases. Type I is more common, with an estimated frequency of somewhere between 1 in 100,000 and 1 in 1 million.

In Type I and Type II, the enzyme in the liver is defective, creating a deficiency of the enzyme AGT. The organ that suffers most is the kidney. Patients typically present kidney stones anywhere from birth to the mid-20s. When very large amounts of oxalate are present in the urine, such as in primary hyperoxaluria, the kidneys can be damaged to the point that they stop working. When excess oxalate build up in the blood it can also spread to the eyes, bones, blood vessels, heart and other major organs.