Hi, I've just create an account and wondering if you could help me with a question. I'm currently studying genetics and undergraduate level and very confused.
I understand that genetic linkage = "Linked genes sit close together on a chromosome, making them likely to be inherited together".
However, what is the difference between genetic linkage and genetic association?
Thank you! Hope this is posted in the correct place.
Genetic linkage is a neutral concept, it is don't depend on phenotype or traits, and it means nearby allele were linked together and then pass to next generation. Genetic association were trait dependent concept, for which, some kinds of allele or genotype are more likely linked to some phenotype or traits. On the other way, genetic linkage is to indicate the genetic-genetic linkage while gene association indicate genetic-phenotype linkage. Just my opinion, welcome to criticize.
Another interesting concept should be also discussed here, that is, linkage analysis. Genetic linkage analysis is a powerful tool to detect the chromosomal location of disease genes. This analysis is also one of most important analysis method to identify disease genes, along with Association Study. It is based on the observation that genes that reside physically close on a chromosome remain linked during meiosis.These analysis usually should be conducted in family/pedigree based genetic data with software of MERLIN, LINKAGE,ALLEGRO.
Genetic association: condition existing between a set of genes and phenotypes (or even among a set of phenotypes) that occurs when such genes/phenotypes are co-present in single individuals with a higher frequency than it would be expected by chance.
Linkage disequilibrium: condition existing among a set of genes that occurs when such genes are co-present in single individuals with a higher frequency than it would be expected by chance.
Genetic linkage: the component of linkage disequilibrium that occurs when two or more genes, because they are physically located on the same chromosome, are co-present in single individuals with a higher frequency than it would be expected by chance. Genetic linkage exists because at meiosis chromosomes are the units of transmissions: recombination among alleles located on the same chromosome only occur as an effect of crossing over (the frequency of which depends, in fact, on physical distance). In turn, alleles located on different chromosomes are said to segregate through independent assortment.
