Hair color is determined by a single nucleotide substitution
Blondes differ from brunettes in one DNA letter
Alexander Khramov, Infox.ru
Geneticists have found out that blondes and blondes appear due to a single mutation. It does not affect any other body functions, except for hair color.
The results of a study conducted by American scientists from the Howard Hughes Medical Institute are published in the journal Nature Genetics: Guenther et al., A molecular basis for classic blonde hair color in Europeans (a press release Subtle change in DNA, protein levels determines blonde or brunette tresses is published on the Stanford School of Medicine – VM website).
Scientists have been investigating the genetic mechanisms that regulate the coloring of animals and humans for many years. Previously, they were able to detect several DNA segments that affect hair color. However, the authors of the article showed that in reality, blondes and brunettes are distinguished by only one mutation occurring in the regulatory region of the KITLG gene.
In this gene, the KIT receptor tyrosine kinase ligand is encoded, that is, the protein under the influence of which this receptor is activated. The development of many cell types depends on the activity of this ligand, for example, blood cells, progenitors of germ cells and melanocytes. Therefore, mutations in the KITLG gene usually cause severe diseases, including infertility and anemia.
By modifying the KITLG gene in various ways, the researchers noticed that the activity of one of its versions decreases by about 20% in the cells of the hair follicles of mice. At the same time, the mutation does not affect the work of KITLG in other tissues. It turned out that such a mutation occurs in one of the regulatory regions of the gene and consists in replacing the nitrogenous base adenine (A) with the nitrogenous base guanine (G).
After experiments with cell cultures, scientists raised genetically identical mice that differed from each other by only one letter (A or G). It turned out that mice homozygous for this mutation, that is, in which A has changed to G in both chromosomes from a pair, become completely white. Heterozygous rodents (their mutation occurred only in one of the two chromosomes) are significantly lighter than their normal relatives.
According to the authors of the article, there is a similar genetic "switch" that allows people to change their hair color with one "click". Most likely, there are many more "switches" in our genome, replacing a single letter in which you can change certain characteristics of the organism without affecting its other properties.
Portal "Eternal youth" http://vechnayamolodost.ru03.06.2014