Narcolepsy Forum Posting

Posted by Sebastiaan Overeem on March 01, 2001 at 03:08:59:

In Reply to: Re: ? mutation found posted by PHILIP on February 28, 2001 at 19:28:05:

Philip,

I assume you are referring to a recent
study in Neurology.

In that study the studied the promotorregion
of the hypocretin gene. As you said, that
part of the gene regulates the amount of
hypocretin product that is being produced.

A polymorphism is not exactly the same
as a mutation. Normally, you refer to a
mutation as a DNA change that leads to an
obvious problem with the gene, leading
to disease. That means that you won't
find such a mutation in the healthy population.

However, not every one's DNA is the same. Every
person differes a lot in the exact contents
of it's DNA. Those 'letter-differences' are
not really mutations, because you find them
a lot in the whole population, but they
don't directly, on their own lead to disease. Thse differences are what you call polymorphisms.

What you DO see now and then, is that the frequency of such a polymorphism is increased
in the population with a certain disease, compared
to the healthy population. You then say that
a polymorphism is ASSOCIATED with a disease, but
needs other factors to result in the disease (it's
pretty much the same as the association of
a specific HLA-type with narcolepsy).

In the neurology paper, they found a polymorphism
in 6 out of 180 (!) patients, but also in
one control. The frequency is increased if you
look at these numbers, but the exact role
of the change is not very clear. Additionally,
this polymorphism only seems to play a (small)
role, in a very small subgroup of narcoleptic
patients.

Oof, sorry for the long story. Maybe I should
have emailed it, instead of posting...

Follow Ups:

• Re: ? mutation found PHILIP 13:02 3/01/01 (7)
  • Re: ? mutation found Sebastiaan Overeem 00:06 3/02/01 (6)
    • Re: ? mutation found PHILIP 12:48 3/02/01 (2)
      • Re: ? mutation found Crissy 21:32 3/03/01 (1)
        • Re: ? mutation found PHILIP 12:15 3/09/01 (0)
    • Re: ? mutation found "FUZZY BRAIN STUFF" rip van winkel 03:36 3/02/01 (2)
      • Re: ? mutation found "FUZZY BRAIN STUFF" DANY 12:36 3/05/01 (1)
        • Re: ? mutation found "FUZZY BRAIN STUFF" rip van winkel 13:52 3/05/01 (0)
• Re: ? mutation found Pat 06:17 3/01/01 (0)

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