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July 5, 2017

Mysterious genetics of vitiligo skin disease

There are not only the disease, seriously life threatening, but also the disease that damage the image of the person rather than his health. Such ailments include vitiligo – “mysterious disease”, in which the skin surface is covered with white (devoid of pigmentation) spots, increases with time, and merging with each other.

On the nature of this phenomenon is known very little – basically, only that it is related to autoimmune processes. An international consortium of scientists conducted a large-scale genetic scan, which revealed several genes, with no regular work, which may be due to progression of the disease. However, this is only the first step – treatment and even the precise molecular and cellular mechanisms of the researchers is to say cannot do anything.

Vitiligo (vitiligo from the Latin -. Cutaneous disease, psoriasis) – a chronic disease, which is expressed primarily in the appearance of depigmented areas of skin, hair which also becomes gray. This phenomenon is caused by disruption of melanocytes – cells that produce skin pigments (primarily melanin) – due to their dysfunction or even death. Vitiligo is an autoimmune nature – that is, the melanocytes die because of the failure detection system of cellular immunity when their own “fabric guards” (macrophages, lymphocytes) are starting to attack the melanocytes and remove them from the system. Other autoimmune diseases – such as thyroiditis and systemic lupus erythematosus, often accompany vitiligo. Preliminary studies have shown that genetic defects that cause vitiligo mainly refer to the genes of the immune system, as well as genes melanocytes themselves.

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This disease, in general, is not dangerous, but it spoils the appearance of the person. A well-known story, when the King of Pop Michael Jackson, originally black, is gradually transformed into the “white man”. This metamorphosis long sucking tabloid press, but, apparently, the transformation was not caused by racial beliefs or something more extravagant, namely vitiligo, the first signs of which appeared in the singer in the early 1980s. The famous white glove with sequins that has become the object of imitation of numerous simulators, served to conceal the beginning of the disease, when the palm of a black actor began to turn white. Later, when the glove and make-up stopped to help, Jackson did plastic surgery to align the overall skin tone – at that time, almost white. In the diagnosis of the “king” and was listed as systemic lupus erythematosus.

The treatment of vitiligo is not there; there are only partial measures to slow down the progression of the disease or reduce its symptoms. First, the patient must use a strong sunscreen because skin is devoid of natural photo filter, quickly burn in the sun, and in it under the influence of UV rays can even begin to develop oncology. However, ultraviolet ranges and A and B are used for the treatment of vitiligo, but, of course, in a controlled clinical setting. In addition to conventional cosmetic formulations, skin tone only leveling, often with the use of corticosteroid ointment, which in some cases can partially restore pigmentation. In addition, there are cases of successful therapy by “cicatrization” in the affected area “their” area of melanocytes from healthy skin cells multiplied in vitro. In addition, there is evidence of healing disease weight drugs derived from natural sources – black pepper, ginkgo, and even human placenta, but these results cannot be considered generally accepted and widespread in the medical and cosmetic practice.

Obviously, a truly effective treatment will not, pending the exact mechanisms of the disease – that is what is happening at the level of individual cells, are destroyed when their own melanocytes, and that is the reason for this “civil strife”. In this era of post-genomic technologies adopted approach to the study of genetic diseases underlying reason quite formal – genotyping large groups of patients with this disease, and comparing the results with the “control” group (consisting of healthy individuals). At the same time, to miss nothing, looking for defects throughout the genome, comparing the differences in the hundreds of thousands of locations around the chromosomes.

The approximate size of the human genome – three billion base pairs, but most of this material is identical not only for any two people, but also, say, the human and chimpanzee (or mouse). The bulk of the difference lies in the so-called single-nucleotide substitutions (or SNIP – from the SNP, single nucleotid polymorphism) – differences in individual “letters” that make up the “word” (gene). Thus variants of the gene differ in one (or more) in the “letters” are called alleles.

By the way, the vast number of SNPs is not within the genes coding for proteins (which are only a little more than 20 thousand), and the “intergenic spaces” that make up the basic DNA mass. The role of this “dark matter” until recently seemed so strange that these areas are even called “junk DNA”, but to date has accumulated a mass of evidence that the “ballast” is actually performs an important regulatory function. By the way, it is possible that it is this DNA plays a crucial role in the evolution of organisms and determines the difference, for example, between a man and the other primates.

Anyway, despite the slow but inexorable approach of the era of “personalized genomics”, when everyone with a birth certificate will receive and medical record with complete sequence of its genome, are now medical genetics compared with each other than whole genomes and only SNPs sets corresponding to the differences between the individuals themselves. This operation is called genotyping, and may be, for example, using DNA microarrays, can provide information immediately about the hundreds of thousands (up to one million!) Single nucleotide substitutions. Such research is much cheaper than a full reading of the DNA of an individual, and a large number of SNPs investigated allows the calculation that results point to differences in the chromosome, presumably associated with a particular disease.

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