What is a marker?
A marker is a unique sequence of nucleic acids found on a strand of DNA. Geneticists are currently finding DNA markers evenly dispersed in the canine DNA. These markers are polymorphic meaning they tend to look slightly different in different individuals. This means that we can tell by looking at a particular dog which grandparent contributed a certain part of its DNA. Genes are arranged on chromosomes in a stable spatial relationship. During reduction division of the germ cells, a phenomenon called “crossing over” occurs, in which parts of analogous chromosomes are exchanged. The liklihood that two genes are separated by crossing over depends on how closely spaced they are on the chromosome. Closely spaced genes tend to stay together during the final division of the germ cells (meiosis). When 2 genes (or a marker and a gene) are close enough in their spatial arrangement on the chromosome to be transmitted together we call them “linked”. If we knew that a particular grandparent carried
A marker is a location on the Y chromosome that may be tested for genetic genealogy. These locations, or markers, have names, such as DYS #19 or DYS #385a or DYS #439. When a marker is tested, the result is reduced to a number, which represents the number of repeated patterns in the DNA at a specific location on the Y chromosome.
DNA testing for Genetic Genealogy focuses on a specific part of the y-chromosome on the DNA strand. There are particular places that the lab looks at (similar to addresses on a street) where patterns repeat over and over. The lab counts the number of times the pattern repeats, and that is your count for that marker. By comparing these counts (the number you see for each address on your test results), you can see how closely you match others who have been tested.
