Variance components can be used to describe the similarities
between individuals in a pedigree. Variance components are specified
with the -w (for the null hypothesis) and -v (for
the alternative hypothesis) options. Variance components may be
combined. For example, to allow for an environmental (e)
and a polygenic (g) component under the null hypothesis
use the -weg option.
|
Value |
Description |
|
e |
Non-shared Environment. This represents the environmental
effects that are unique to each family member, including measurement
error. This component of variance is fitted using the identity
matrix. |
|
g |
Polygenic. These effects are a function of relatedness
between family members and may be due to polygenes. This component
of variance is fitted using the kinship matrix. |
|
a |
Additive Major Gene Effect. This represents the additive
effect of linkage to a major gene. This component of variance
is fitted using pi-hat measure derived from the IBD matrix between
relatives. |
|
t |
Twin Environment. This represents the environment shared
by twins, but not other types of relatives. |
|
c |
Common Environment. This represents the environment shared
by all related individuals. |
|
n |
Nuclear Family Environment. This represents the environment
shared by all members of a nuclear family. |
|
d |
Dominance Major Gene Effect. This represents the dominance
effects of linkage to a major gene, and is fitted using the probability
of sharing two alleles between relatives. |
