UC Davis Labs DNA Test
What is HCM?
Hypertrophic cardiomyopathy is the most common cardiac disease in cats. Affected cats are at risk of sudden cardiac death due to defects that produce increased left ventricular heart muscle thickness. In Ragdolls, the condition is inherited due to breed specific mutations in the cardiac myosin binding protein C gene (MYBPC3).
The Ragdoll HCM mutation, known as R820W, is a single base pair change in MYBPC3 that is thought to alter the shape and function of this essential protein for normal heart muscle development. The same R820W mutation has been found to be associated with HCM and left ventricular non-compaction in humans (see reference below, Ripoll et al. 2010). Recent studies show cats that are heterozygous (1 copy) for the mutation are not likely to show signs of the disease and may live a normal lifespan. Homozygous (2 copies) cats for the mutation are at high risk of developing severe HCM signs, usually between 1-2 years of age and have a greater likelihood of early cardiac death. Infrequently, homozygous cats do not show clinical signs of HCM.
Breedings between 2 heterozygous cats are expected to produce 25% high risk kittens. It is not recommended to use cats homozygous for the R820W mutation in a breeding program.
Testing for the Ragdoll HCM mutation to helps owners and breeders identify the Ragdoll HCM status of their cats.
What is PKD1 ?
Polycystic Kidney Disease (PKD) is a well documented abnormality in domestic cats. Cystic kidneys can sporadically occur in any population of cats. PKD is not a new disease and has been reported in the literature for over 30 years. The heritable form of PKD1 may not have initially occurred in Persians as a new mutation, but perhaps in random bred cats. Unfortunately, PKD1 does not have a strong clinical presentation. The presentation of PKD1 is similar to one of the most common causes of death for any cat, renal failure. Thus, PKD1 has gone unnoticed for many years and has spread throughout the Persian breed. Any breed that has used Persians in their foundation or propagation should have concerns for PKD1.
Early onset, bilateral presentation (both kidneys), and multiple cysts are all traits of the heritable form of the disease. The kidney cysts for PKD1 present early, often before 12 months of age. Renal failure, however, usually occurs at a later age. Thus, PKD1 is considered a late onset renal disease. In the fancy cat breeds, PKD1 is inherited as an autosomal dominant condition. This implies that only one copy of the altered version of the gene is required to produce PKD1. Generally, 50% of PKD1 positive cats’ offspring will inherit PKD1. A positive cat could potentially be homozygous for PKD1 and all offspring produced would have PKD1. It is suspected that cats that are homozygous for PKD1 are not abundant and the homozygote form could be lethal in utero or severely affected at a very early age. Further research is required to determine the effects of the homozygous condition.
It is estimated over 37% of Persians have PKD1, a breed that accounts for nearly 80% of the cat fancy. Many lines and catteries have been able to greatly reduce this frequency by using ultrasound screening methods and improved breeding practices.