|What is it?|
Marker analysis is a genetic technique whereby the sequence of the gene is not directly analyzed, but the mutant copy (allele) of the gene is inferred through analysis of a genetic marker. Genetic markers are polymorphic genetic sequences, such as microsatellites or RFLPs, which allow differentiation of the chromosomal alleles. Inheritance patterns within a family are traced and the mutant allele identified by comparing the alleles of affected and unaffected individuals.
When is it used?
Marker analysis would be used, rather then direct examination of the gene, for several reasons:
How Does it Work?
The figure on the right illustrates the relationship between the components of marker analysis. The gene and marker are located very close to each other on the same chromosome (sometimes the marker is located within the gene). The gene is mutated, but we do not analyze that mutation directly, but rather use the marker to identify which copy of the chromosome has the mutant gene on it.
|The colorized representation of the gel corresponds to chromosome diagram above. The affected individuals share the green allele, thus we infer that the mutant gene is on the green allele. Offspring that inherit the green allele are at risk for developing the disease, while those who inherit the pink allele do not have an increased risk for the developing the disease.|