There are several types of molecular genetic markers. Until recently, microsatellites (SSR or STR) were very popular. However, microsatellites are not enough for fine mapping of individual regions of genomes; the high cost of equipment and reagents and the development of automated methods using SNP chips are pushing them out of practice.
A very convenient type of genetic marker is SNP (Single Nucleotide Polymorphisms) – SNP, in other words, single nucleotide polymorphism – these are differences in a DNA sequence of one nucleotide size in the genome of representatives of the same species or between homologous regions of homologous chromosomes of an individual. SNPs are point mutations that can occur as a result of spontaneous mutations and the action of mutagens. SNPs are widely distributed in the genome. No other type of genomic difference is capable of providing such a density of markers. In addition, SNPs have a low mutation rate per generation (~ 10-8), in contrast to microsatellites, which makes them convenient markers for population genetic analysis. The main advantage of SNPs is the ability to use automatic methods for their detection, for example, the use of DNA templates.
In order to increase the number of SNP markers, a number of foreign companies have recently been joining their efforts, creating a unified database in order to be able, by testing a large number of animals tested for productivity for polymorphism, to reveal the presence of links between known point mutations and productivity.
Currently, a large number of polymorphic variants of genes and their mutual influence on the productive traits of pigs have been identified. Several genetic tests using production markers are publicly available and used in breeding programs. Using these markers, you can improve some of the performance indicators.
Examples of productivity markers:
- fertility markers: ESR (estrogen receptor gene), EPOR (erythropoietin receptor gene);
- markers of resistance to diseases: a gene for the receptor ECR F18;
- markers of growth efficiency, meat productivity – MC4R, HMGA1, CCKAR, POU1F1.