We would like to thank Diane, of New Zealand, for giving permission for anyone to use this letter and for getting permission from Dr. Spier to use it wherever she thought it may help.
Letter From Dr. Sharon Spier, DVM, PhD
From :  Sharon J Spier <sjspier@ucdavis.edu>
Sent :  Sunday, 14 December 2003 3:08:03 p.m.
To :  "Diane" <>
Subject :  Re: HYPP Testing

Dear Diane, Thank-you for your question.  I will try to explain.  The
genetic test is not specific for Impressive or any other bloodline. 
The test is 100% accurate for the mutation that causes HYPP, and to
date, only this mutation, and  the disease,

HYPP, have been
identified in descendants of Impressive.  The test was validated in
this bloodline, because that is the bloodline where veterinarians and
horse owners world-wide were seeing disease.  We have not been able
to trace the mutation further in the QH breed, but if the mutation
arose from parents of Impressive, then we would be able to detect it.

In humans, and theoretically in horses, other mutations in the sodium
channel could cause HYPP.  We have not experienced this in horses
(that  veterinarians have seen HYPP in other bloodlines)  If this
occurs in the future, then sequencing studies could reveal another
mutation and another test could be developed.  The test identifies
the specific genetic mutation that causes an amino acid
in an important portion of the skeletal muscle sodium channel.

I hope this helps.  Let me know if anything needs to be clarified
further.  This disease is not good for the overall health of the
horse.  If people would just see this, then I don't think there would
be so much controversy.  Sharon Spier, DVM, PhD
Diane is a member of the NN Alliance
The last part was highlighted by the Bringing Light Group