True or False..
It is difficult to predict recurrence for polygenic traits?
true
Define Empiric Risk and what it's based on
predictions of recurrence based on trait's incidence in specific population
based on observations/epidemiological studies
Define Heritability
% of phenotypic variation due to genes
H=1 genes only
H=0 environment only
Heritability is a component of phenotype attributed to genes
Define Correlation coefficient
proportion of genes relatives share
Heritability example:
-Mendelian trait: expect it in 50 sibling pairs
-Trait is only observed in 37 pairs
What is the heritability?
.37/.50= .74
State the degree and percent of shared genes for each:
1. Siblings
2. Parent and child
3. Uncle/aunt and niece/nephew
4. Grandparent and grandchild
5. First cousin
1. degree 1, 50%
2. degree 1, 50%
3. degree 2, 25%
4. degree 2, 25%
5. degree 3, 12.5%
Adoption Studies
adopted people share environement, but not genes
share genes but not environment with biological parents
Twin Studies
better info than adoption studies
Concordance-percent (%) of pairs in which both twins express the trait
Define SNP
stands for: single nucleotide polymorphism
a nucletoide site with more than one allele is a polymorphism
site is polymorphic is allele is present in >1% of the population
on average, between two random individuals, there is one SNP every 1000 bases
--> ~3 million differences
Association Studies
studies which compare group of interest
controls are matched: age, ethnicity, gender, enviornment
if SNP is present more often in cases then controls, it is associated with trait and implies SNP may be near gene impacting trait
