Epilepsy: Genetic Research on Poodles
Subject: Epilepsy in Poodles: Part 2C: Current Status of Research on Epilepsy in Poodles
Date Tue, 11 Nov 1997 14:46:56 -0500
From: Barbara Licht
CONTINUED FROM PART 2B
Hopefully, the example I presented in Part 2B illustrates the importance of obtaining information on SPs who are related to those with seizures. In this example, information on those mated to affected SPs and all their offspring were used to help test the hypothesis that the disorder was autosomal dominant. Information on the parents, grandparents, littermates, other siblings, and half-siblings of an affected individual also are needed to test various hypotheses. IMPORTANTLY, if the mode of inheritance is complex, as we expect is true for epilepsy, it also will be necessary to include more distant relatives, such as aunts, uncles, cousins, great aunts, etc. Hopefully, this example also has illustrates how much time, energy, and detective work goes into computing one simple percentage.
My choice of an autosomal dominant disorder may have surprised some of you because we usually expect disorders/diseases to be recessive rather than dominant. Indeed, there are many who believe that primary epilepsy in dogs is recessive. However, it is important to also test the possibility that at least some "subtypes" of primary epilepsy in dogs are dominant, perhaps with incomplete penetrance. With human epilepsy, there are some "subtypes" of primary epilepsy whose genetic basis has been studied fairly successfully. In each case, the disorder is autosomal dominant with incomplete penetrance. In contrast, there are some human "secondary" epilepsies whose genetic basis has been studied fairly successfully. These tend to be recessive. Unlike primary epilepsy, these secondary epilepsies involve neurological deterioration and mental retardation in addition to seizures.
_Progress in Phase #2._
As of December, 1998 (one year after this post was originally written), we have received pedigrees from 70 owners of SPs with seizures and 35 pedigrees of non-seizing SPs who are related to those with seizures. We did not request pedigrees from owners/breeders whose SPs were not known to seize or to be related to an SP with seizures. However, a number of these owners/breeders graciously volunteered these pedigrees.
Phase #3.
We currently (December, 1998) are beginning Phase #3 of our research. In Phase #3, we will be collecting information that will help us differentiate between cases of seizures that are due to primary epilepsy and cases of seizures that are symptomatic of another disorder. We also will begin collecting information that will help us determine if there are different subtypes of primary epilepsy.
More specifically, we are asking owners and breeders to complete a more detailed written questionnaire on selected SPs and complete a follow-up telephone interview. We also are requesting copies of veterinary records for selected dogs with seizures.
When appropriate, we will request blood samples of selected Poodles with seizures and their relatives so that we can search for the gene(s) that cause epilepsy. With the necessary help of poodle owners and breeders, we are optimistic that we will have some useful answers in the next couple years.
Barbara
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Barbara G. Licht, Ph.D. Phone: (850) 644-6272
Department of Psychology FAX: (850) 644-7739
Florida State University email: blicht@psy.fsu.edu
Tallahassee, FL 32306-1270