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Population genetics considerations by Nan Laird,
Professor of Biostatistics at the Harvard School of Public Health.
The discipline of population genetics
is concerned with the distribution of genes in a population.
In this talk, we will focus on concepts from population genetics that aid in the design,
analysis and interpretation of studies of association between diseases and genes.
We'll begin by reviewing some basic terminology.
A genetic marker's a variable which describes
the DNA sequence of an individual at a particular location on the chromosome.
Alleles refer to the different possible values
assigned to the DNA sequence at the marker.
For convenience, we often denote the different alleles at a marker by A, B, C, etc.
Genotype refers to the pair of alleles at
a locus that an individual inherits from their two parents;
one from the mother and one from the father.
Phenotype refers to any observable characteristic in an individual.
It can be used to refer to the values of an observed genetic marker.
But in this talk,
we will use the term to describe a disease related
characteristic or more commonly, a trait.
The disease susceptibility locus or DSL for short,
is a convenient construct used to denote
a particular genetic locus believed to influence the trait under study.
It may or may not coincide with an observed marker.
Finally, the genetic model is used to describe how the number of copies of
the disease allele at the DSL influences the trait.