Genetic Research Strategies:
The Example of Canine Epilepsy

Barbara G. Licht, Ph.D.
Mark H. Licht, Ph.D.
Kathleen M. Harper, DVM, Ph.D.
Department of Psychology
Florida State University
Tallahassee, FL 32306-1270

Introduction

The first step in understanding a genetic disease is determining the mode of inheritance. Geneticists and statisticians examine the patterns of inheritance for the disease to determine if the disease is influenced by several genes or primarily by one gene. They also try to determine if the disease is recessive (both parents must be carriers in order for an offspring to have the disease) or if it is dominant (only one parent needs to be a carrier for an offspring to have the disease).

To determine the mode of inheritance, information is needed on which individual dogs have the disease and which of their relatives did and did not inherit the disease. In most studies, these relatives include littermates, parents, grandparents, and offspring. However, if the pattern of inheritance is complex, as we believe it is for epilepsy, information also must be collected on other relatives, such as aunts, uncles, and cousins. Sometimes, the people collecting these data are scientists, sometimes they are dedicated dog lovers, and sometimes they are both at the same time. What is important to know is that this is a long tedious, but crucial process. What is even more important to know is that it is the breeders and owners that possess the very valuable information that is needed for this research. All the scientists in the world can not find the genes that are responsible for diseases in dogs without the information possessed by owners and breeders.

With respect to our research on the mode of inheritance for primary epilepsy in Poodles, I will begin with a fairly standard line that you have heard from many other researchers. That is, on a general level, we have made considerable progress, but we have a long way to go. Below, I will be more specific. I have joked before that I am not capable of giving a short answer to any question. However, I think it is important to explain the reasons for our procedures as well as our findings.

For each phase of our research, I will describe our goals, the importance of these goals, and the degree to which we have reached our goals. This report will include Standard Poodles (SPs) only because we are focusing on Standards first. Later, we also will focus on Miniatures and Toys. Importantly, we welcome new participants who own any variety. The data we collect on Miniatures and Toys at this time will give us a "head start" for when we focus on those varieties.


Phase 1 Goals

During Phase 1, our goal was to collect short "preliminary" questionnaires from ALL owners and breeders of Poodles (all varieties), even if they never had problems with seizures. The purposes of the preliminary questionnaire are:

  1. To identify SPs with seizures and non-seizing SPs who are related to those with seizures,
  2. To obtain a rough estimate of the prevalence of primary epilepsy in the breed.
  3. To identify potential participants for later research which will focus on environmental determinants of seizures.

Importance of Phase 1 Goals

It should be pretty clear why we want to identify Poodles with seizures. After all, how can we study seizures in Poodles without a large and representative sample of Poodles that have had seizures? Many of you also understand why we need to identify NON-seizing SPs who are related to SPs with seizures. (This is explained below.) However, it is least obvious why we wish to receive questionnaires from those who own Poodles that are unrelated to ones with seizures. First, in order to obtain a more accurate estimate of the prevalence of primary epilepsy in Poodles, we also need responses from those who have not had problems with seizures. Otherwise, we might overestimate the prevalence of epilepsy. Although it is impossible to avoid this problem entirely, we are making a strong effort to minimize it by repeatedly encouraging broad participation.

It also is important to obtain questionnaires from those who have not have problems with seizures because for our later research on the environmental determinants of seizures (e.g., vaccines, pesticides, etc.), we will need to compare the environments of Poodles with and without seizures to see if their environments differ. Last, and importantly, some individuals who own Poodles who are related to those with seizures may not realize it. Thus, if those owners are already in our database, we will not have to spend time and money tracking down their address and phone.

Progress in Phase 1

Phase 1 has been successful. However, it is NOT too late to become a participant. Thus far, we are pleased to report that more than 250 owners/breeders of SPs have filled out our preliminary questionnaire and have indicated a willingness to provide further information. Our respondents own an average (mean) of approximately 4 SPs, with a range of 1 SP to 25 SPs. The most common number owned was 1; and the higher numbers reflect breeders who had a litter on the ground at the time they filled out the questionnaire. Our Phase 1 findings include information on almost 1,000 SPs that are spread across a wide range of ages.

Thus far, we have identified owners of 87 SPs with seizures. Additionally, 24 respondents reported that a current SP has produced at least one offspring that has had seizures, and 31 reported that they know of a parent or grandparent of a current SP that has had seizures. Thus, Phase 1 data helped us identify a significant number of SPs with seizures and a significant number of relatives.

As an aside, conducting research on a disease puts one in a strange psychological position. Every time I receive information on a new Poodle with seizures, I am deeply saddened by the suffering of both the owner and Poodle. Because one of our own SPs has epilepsy, I know exactly what the owner is feeling, and it is heartbreaking. However, at the same time, I know that every time we identify another potential participant, we get one step closer to our goal of determining the mode of inheritance for primary epilepsy in SPs. This, in turn, can bring us closer to our long-term goal of identifying the gene(s) that influence primary epilepsy in all varieties of Poodles and other affected breeds.

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