Primary Hyperoxaluria Type 2

Primary hyperoxaluria type 2 is a genetic disease that mainly affects young felines, characterized by the accumulation of oxalate crystals in the kidneys leading to renal failure along with dehydration, anorexia and even muscular and neurological problems. This condition is caused by a mutation in the GRHPR gene, which encodes a crucial enzyme in the degradation of glycolate and glycerate.

Symptoms

The development of hyperoxaluria leads to acute onset of renal failure in the first year of life. Clinical signs include dehydration, anorexia, depression and weakness. As the disease progresses, azotemia (increased levels of nitrogenous compounds) develops and neurological signs may appear. In addition, generalized muscle atrophy is observed due to improper functioning of motor neurons and accumulation of neurofilaments in these neurons.

Disease Management

Treatment of this disease focuses on decreasing oxalate production and preventing the formation of kidney stones through dietary changes. In addition, it is important to maintain good hydration.

Genetic basis

This disease follows an autosomal recessive mode of inheritance. Autosomal recessive inheritance means that the cat, regardless of sex, must receive two copies of the mutation or pathogenic variant to be at risk of developing the disease. Both parents of an affected cat must carry at least one copy of the mutation. Animals with only one copy of the mutation are not at increased risk of developing the disease, but may pass the mutation on to future generations. Breeding between cats carrying genetic variants that may cause disease is not recommended, even if they do not show symptoms.

Technical report

Primary hyperoxaluria type 2 in cats is a genetic disease that mainly affects young cats, causing acute renal failure due to the accumulation of oxalate crystals in the renal tubules. This condition is characterized by increased levels of L-glyceric acid in the urine. The gene affected in this disease is GRHPR, which encodes an enzyme involved in the glycolate and glyceric acid degradation pathway. The causative variant in the GRHPR gene is a point mutation in intron 4, which results in the deletion of exon 5 and leads to the production of an abnormally short and non-functional protein.

Most affected breeds

Burmese
Himalayan
Persian

Bibliography

Goldstein RE, Narala S, Sabet N, et al. Primary Hyperoxaluria in Cats Is Caused by a Mutation in the Feline GRHPR Gene, Journal of Heredity, Volume 100, Issue suppl_1, July-August 2009, Pages S2-S7.

McKerrell RE, Blakemore WF, Heath MF, et al. Primary hyperoxaluria (L-glyceric aciduria) in the cat: a newly recognised inherited disease. Vet Rec. 1989 Jul 8