Posted by Scott R. King on January 24, 2000 at 19:33:19:
In Reply to: Re: Blood test to predict diabetes in children posted by Conrado Sánchez López on January 22, 2000 at 12:54:45:
Conrado--
I will try to answer your original question. In you situation, what is that chance of another child developing diabetes?
As you posted:
Risk of to develop DMID
Normal population 0.4%
Father or mother diabetic 3.0%
A brother diabetic
Identical twin 33%
Identical HLA 15%
Half Identical HLA 5%
Different HLA 1%
When the child is conceived, the genetic makeup goes from a probability spectrum to something actual. The probabilty at that point will be: (Obviously identical wtin is out of the question.) The probability of identical HLA is close to 1:4, half identical 1:2, different 1:4.
So:
25% probability HLA 15%
50% probability Half Identical HLA 5%
25% probability Different HLA 1%
So the probability of diabetes BEFORE CONCEPTION is:
((0.25 X 15%) +
(0.5 X 5%) +
(0.25 X 1%)) / 4 +
6.5%.
After conception it would be possible to do an HLA test and determine the revised probability.
This is only approximate because you know the actual alleles in play. A genetic counselor can give you more precise probabilities.
Scott R. King