Multifactorial disorders Flashcards
What is a liability distribution?
A bell curve of phenotype distribution in a population
What is the threshold of liability?
It is the number of contributing alleles needed to be considered diseased.
Which is higher in multifactorial diseases: the recurrence risk, or the occurrence risk?
Recurrence risk
Why is the recurrence risk higher for multifactorial diseases?
[1.] Because it is not known how many contributing alleles a parent has, [2.] meaning that the birth of an affected child gives more information about how many contributing alleles the parents have.
What is pyloric stenosis? What type of inheritance pattern does it follow?
Tightening of the pyloric sphincter, leading to frequent vomiting. Follows the multifactorial inheritance pattern, with males being affected (having a lower threshold) than females.
What is the general population risk for birth defects?
0.5%
If a second degree relative is affected with a birth defect, what is the new risk of developing the condition?
2%
If a first degree relative is affect with a birth defect, what is the new risk of developing that disease?
3-4%
If two first degree relatives are affected with a birth defect, what is the new calculated risk?
5-8%
If three first degree relatives develop a birth defect, what is the new calculated risk?
9-12%
If an identical twin develops a birth defect, what is the new calculated risk for the other twin?
20-30%
What are haplotypes?
When multiple alleles are contributed as a unit due to their close proximity
What arms of the HLA haplotypes are associated with DM I development?
Dr-DQ
What are susceptibilty alleles?
Alleles that make one more prone to developing a disorder (e.g. some DM I haplotypes)
What are protective alleles?
Alleles that make one less prone to developing a disorder (e.g. some DM I haplotypes)
