Primary Hyperoxaluria: Type 2

Primary hyperoxaluria type 2 (PH2) is an inherited disorder that is caused by the deficiency of an enzyme named glyoxylate reductase/hydroxypyruvate reductase (GR/HPR). People with PH2 have excessive accumulation of insoluble calcium salts in various tissues of the body, especially the kidney. PH2 causes recurrent kidney stones, which, if untreated, can cause life-threatening kidney failure. Age of onset of symptoms is typically in childhood. Affected individuals may also experience problems in their bones, eyes and heart due to the accumulation of calcium salts in these tissues. Intellect is not affected by PH2. There is no cure for PH2. People with this condition need to drink plenty of water and take medications to minimize kidney injury. Kidney transplantation may be needed at the time of kidney failure. PH2 is caused by pathogenic variants in the GRHPR gene.

PH2 is inherited in an autosomal recessive manner. This type of inheritance requires the presence of two copies of a pathogenic variant in the gene for a person to have the genetic disease. Both parents must be carriers of a pathogenic variant in the gene in order to be at risk to have an affected child. The child must inherit a pathogenic variant from each carrier parent in order to be affected. There is a 1 in 4 chance that a baby will inherit two mutated copies of the gene and be affected when both parents are carriers.

There are generally no signs or symptoms associated with being a carrier for PH2. However, the risk to have a child affected with PH2 is increased. Testing of reproductive partners is recommended for carriers of PH2.

PH2 is thought to be less common than primary hyperoxaluria type 1, but the exact occurrence is unknown.

Genetics Home Reference: Primary hyperoxaluria (http://ghr.nlm.nih.gov/)
Genetic Alliance: Primary hyperoxaluria type 2 (http://www.diseaseinfosearch.org/)
Oxalosis & Hyperoxaluria foundation (http://www.ohf.org/)

OMIM [HYPEROXALURIA, PRIMARY, TYPE II: 260000] (http://www.ncbi.nlm.nih.gov/omim)
Gene Reviews: Primary hyperoxaluria type 2 (http://www.ncbi.nlm.nih.gov/books/NBK1116/)

• Full gene sequencing