Re: [pyrnet] recessives

[Patric Lundberg <pyrsrgr8@yahoo.com>]

Carol,

> Using the same premise, would not indeed the number of carriers
> reduce in the overall population causing a decrease in the numbers
> having the disease?
> 
> Or is there some biological anomaly that will prevent this from
> happening?

You are entirely correct - the same principle applies (and yes, fewer
dwarfs should be the outcome).  To get back to the probability
scenario, it is quicker to raise a low percentage by adding more
carriers than it is to lower that percentage by adding non-carriers.

For example, if you buy one lottery ticket out of a hundred sold you
have the obvious 1% chance of winning.  Buy another and you chance
nearly doubles - you now have 2 of 101 tickets (1.98%).  Now, by adding
tickets to the pool (bought by others), say 10 more, you now hold 2 of
a total 111, or 1.80%.  So, by adding one more ticket, you doubled your
chances (+98%), yet when 10 more tickets were subsequently bought by
others, your overall chance barely dropped (-9.1%) from before.

This is what I meant by the number of carriers in the overall
population increasing until you get to a steady-state level where
influx and efflux pretty much match each other.  Without a direct
genetic test for the carrier allele, we can never eliminate such a
defect from the population - that is, breeding presumed clear to
presumed clear won't do it.

Even if you may be whittling away at the overall numbers by this
approach, all it takes is one popular sire to be a carrier and years of
slow reduction in total carrier frequency is undone.

Hope this wasn't too muddled...

Patric



=====
"Sage Advice Improves with Thyme"

Patric Lundberg, PhD
patric@pyrealm.com
Department of Virology
City of Hope National Medical Center
(626)359-8111 x2612

__________________________________________________
Do You Yahoo!?
Yahoo! Shopping - Thousands of Stores. Millions of Products.
http://shopping.yahoo.com/