JUVENILE RENAL DYSPLASIA (JRD)

                                           Discovery of the Mutation and development of a direct DNA test for JRD.

                                                                         What is JRD?

Juvenile renal dysplasia (JRD) is an important category of kidney diseases incanines. Dysplasia is defined as abnormal growth    or development of cells ororgans. In the case of JRD the kidney fails to develop properly during embryogenesis in the womb.

At birth immature structures consisting of undifferentiated fetal cells or tissue types are found in the kidney, and are persistent     throughout the life of the animal.JRD can present itself with a wide range of symptoms and pathological findings. Definitive           diagnosis of JRD is done by a wedge biopsy which revealsdysplastic lesions, including abnormal ducts, and glomeruli.           Individuals with anabnormal biopsy can be asymptomatic, showing no signs of the disease. On the other hand, they may            present  classic signs of chronic end stage renal failure, or somewhere between these two extremes. Given this broad

            spectrum of symptoms affected individuals often go unnoticed, and remainin the breeding population.

        This is why development of a genetic test was necessary for the management and elimination of this disease.

                                                                    JRD a Closer Look

What you see is not always what you get. For those breeders that deny that JRD is a problem in their kennel, you would see it    if you had done biopsies on your dogs.     Below is a summary of an article by Dr. Kenneth C. Bovee.  In October of 2003,

Dr. Kenneth C. Bovee from the University of Pennsylvania published his findings in the Shih tzu from a 10 year study involving  143 dogs and 52matings. His findings clearly show that the majority of breeding stock had some level of fetal glomeruli, and estimates from this study indicated that the prevalence of this defect (meaning biopsy positive fetal glomeruli) was probably about 85% in the breed, however the actual clinical cases that manifested severe renal dysfunction was low.  Other critical conclusion from this 10 year study was that animals with a low percentage of fetal glomeruli could produce those with renal disease and even the breeding of 0% fetal glomeruli (biopsy negative) adults resulted in offspring with 1-3% fetal glomeruli.

  The apparent low incidence of disease was a danger to the breeding population as seemingly normal adults could go undetected in the breeding population, and produce clinically affected offspring. Further, while using biopsy data to try and          control this disease in the breeding population limited to some degree the production of severely affected progeny, this was        not entirely successful in eliminating the transmission of biopsy positive offspring from the parents.   Further Dr. Bovee speculated, based on these findings that the mode of inheritance was not a simple recessive, and could follow a pattern of dominant with incomplete penetrance.Thus the development of a genetic test was imperative to control this disease in this breed as well as others. Truer words were never spoken! The following is a quote from an article by Susan L Fleisher.

While Susan was a lay person, her personal tragedy with the death of her Standard poodle puppy with JRD led her on a quest to discover everything that she could about the disease. She wrote several of the most comprehensive and probably the most cited articles on JRD on the internet. Her article is not only well referenced from the scientific literature, but her quote below best summarizes the main problem with JRD that exists to this day. Even though this was written over a decade ago, the frustration with this disease and the failure of recognition of this disease as genetic remains today. Susan passed away in 2007, but her legacy remains in her articles on JRD. Everyone needs to read her article(s) that are available on the internet on many sites (see for example http://www.vetprof.com/clientinfo/juvenilerenal.html ).

"The information I have gathered since then leads me to believe that most individual cases of JRD are treated by owners and veterinarians as isolated occurrences rather than as the manifestation of a genetic disease. If the breeder is informed about a medical problem in a puppy she has sold, and often she is not, or, if just the owner of the dam is informed, and it is only one puppy in a litter about whom she is informed, it is again treated as an isolated incident. Unless there are multiples in a litter it

goes largely unrecognized, and no recognition is made nor thought given to those littermates who are carriers."