Polycystic Kidney Disease

Polycystic kidney disease is an autosomal dominant inherited condition characterized by the formation of renal cysts, which can lead to renal failure and usually manifest before the age of seven years in most cases. This disease mainly affects breeds such as the Persian and its variants, altering the normal function of the primary cilia in the renal tubular cells.

Symptoms

The disease is characterized by renal insufficiency and the presence of cysts in the kidneys from birth, which increase in number and size with the age of the cat, generally manifesting clinically at around seven years of age. Symptoms include apathy, loss of appetite, weight loss, lethargy, increased water intake and urination, as well as gastrointestinal problems. The disease may also present with hepatic manifestations, such as liver cysts, although this is less common.

Disease Management

There is no curative treatment, but symptoms can be alleviated with palliative care.

Genetic basis

This disease follows an autosomal dominant mode of inheritance. Autosomal dominant inheritance means that cats only have to inherit one copy of the mutation or pathogenic variant to be at risk of developing the disease. Each kitten born to a parent carrying one copy of the mutation has a 50% chance of inheriting one copy of the mutation and being at risk for the disease. Breeding between cats carrying genetic variants that can cause disease is not recommended, even if they do not show symptoms.

Technical report

Polycystic kidney disease is an inherited condition characterized by the progressive development of cysts in the kidneys, which deteriorate the renal tissue and lead to an irreversible decrease in renal function. In cats, this disease is common, mainly affecting breeds such as the Persian and its variants, although it can also be seen in other breeds such as Ragdoll and Scottish Fold. The gene involved, PKD1, encodes the polycystin-1 protein, which is essential for the structure and function of the primary cilia in renal tubular epithelial cells. These cilia participate in the perception of fluid flow and cell orientation, influencing processes such as polarity, cell differentiation and response to growth signals. It is estimated that the loss of cilia polarization alters the water reabsorption function favoring the development of cysts in the parenchyma, although the etiology of the disease is not yet fully understood. The causative variant, identified in the PKD1 gene, involves a transversion that generates a stop codon in exon 29, resulting in the loss of approximately 25% of the C-terminal end of the protein.

Most affected breeds

American Shorthair
Exotic Shorthair
Maine Coon
Munchkin
Persian
Ragdoll
Scottish Fold
Siberian

Bibliography

Lyons LA, Biller DS, Erdman CA, et al. Feline polycystic kidney disease mutation identified in PKD1. J Am Soc Nephrol. 2004 Oct