18. Gene Mapping Flashcards
Unit for measuring percentage of recombination.
Centimorgan
Describe the linkage phase with gene mapping.
Using an allele known to be “linked” with a mutation in a gene in order to screen for a disease.
Explain the LOD scores presented in lecture.
LOD score indicates liklihood that genes are linked.
- Score of 3 or above means two genes 1000x more likely to be linked.
- Score of -2 or less means two genes 100x less likely to be linked
Common markers used for mapping genes to locate linked genes.
Microsatellites
When is the information obtained mapping genes not useful as data or considered “uninformative mating”? (2 instances)
- Same marker allele on both chromosomes
2. Cannot follow through subsequent generation
Describe linkage disequilibrium.
Normally mutations can be detected by looking for markers of alleles that are linked to the gene that is mutated. Over time enough recombinations occur that can separate these genes. What was once a 100% linkage eventually drops off to 25% or lower. Closer genes take longer to recombine but eventually you need to find a new marker to detect the mutation.
Example presented in class of a disorder that has undergone linkage disequilibrium.
Hemochromatosis and the linked HLA-A3 gene
Term meaning prediction of a patient having a disorder when linkage is not known or may not be a factor. Some specific allele significantly increases risk of a person being affected.
Genetic Association
Example of genetic association presented in class.
Ankylosing spondylitis and HLA-B27. People with B27 90x more likely than others to have ankylosing spondylitis
Technique used to locate genes using micro arrays and SNP analysis.
Genome Wide Association Studies
Collection of data containing gene copies for specific tissues.
cDNA library
DNA sequences that MAY be responsible for a given trait.
Candidate Genes
