What if there was a DNA test for epilepsy?

[I wrote the following in November 2014 for the Norwich breeders list.]

During the recent discussion about epilepsy, I noted that various people made the following comments:

1. It is a health problem that affects quality of life.

2. Breeders should avoid spreading the mutation or mutations that cause the problem.

3. Breeders should be open about the problem.

4. There was a wish for a DNA test for the problem.

Epilepsy is almost certainly a polygenetic disease (meaning that several genes are involved). If epilepsy was a single gene disease, that gene - and the mutation causing epilepsy - almost certainly would have been discovered by now. So assuming epilepsy is polygenetic, what will most likely happen is that some - but not all - of the causative genes will initially be discovered. So most likely initially there will be a DNA test for epilepsy that will identify mutations highly correlated with the problem, but not all the genes involved.

What if there was such a DNA test for epilepsy? Would you use it? (I hope you would say "yes" ...)

Or would you find acceptable one of the following:

1. Epilepsy is not in my line. I have never seen it.

2. Epilepsy is a small problem for the breed. (According to the Norwich OFA health survey, only 3.3 percent of Norwich were reported with a neurological or muscular disorder.) What we need is a DNA test for a major problem like UAS.

3. The DNA test does not definitely show epilepsy as not all of the genes have been discovered.

Do you find these acceptable reasons for not DNA testing for epilepsy? (I hope you would say "no" ...)

Now what about primary lens luxation (PLL) and degenerative myelopathy (DM)? Both these health issues affect quality of life. I assume all breeders would say that we should not spread their causitive mutations. Yet, I have heard these exact same excuses made as reasons for not PLL and DM testing.

We currently do not have a DNA test for epilepsy. I will do the happy dance - and use such a test - when it becomes available.

But we do have DNA tests for PLL and DM. Why are most Norwich breeders not using them? Why are some Norwich owners not being open about their dogs' PLL and DM status on the OFA web site?

If there is something different about epilepsy as opposed to PLL and DM - other than one is something about which we can do very little, and the other two have DNA tests that change them from problems into minor faults that we can breed around - someone please explain it to me.