Is Vitiligo Genetic
Vitiligo is a type of skin disorder in which there are patches of depigmented skin resulting from progressive autoimmune loss of melanocytes from the areas involved. When vitiligo usually appears as white patches, they can show on any part of the body. However, the areas exposed to the sun are more commonly affected by vitiligo, including the face, arms, neck, and legs. We often get asked, "is vitiligo genetic?" Genetic almost certainly has something to do with it, and in this post, we'll dig deeper into the relationship between vitiligo and genetic.
Vitiligo Thought to Be Associated with Autoimmune Diseases
While the primary cause of vitiligo is currently unknown, it is thought to be associated with autoimmune diseases. Vitiligo is an autoimmune order, which means the immune system identifies the body's healthy tissues and cells as an intruder and attacks it, eventually destroying them. One of the leading underlying causes of vitiligo is the immune system attacking the pigment-producing cells known as melanocytes.
The melanocytes produce melanin, responsible for the skin, hair, and eyeball color. When the immune system attacks the melanocytes, it results in melanin loss in different parts of your body, causing vitiligo. As earlier discussed, genetics has been identified as one of the primary reasons behind the immune mechanism.
Complex Interaction of Several Factors
Vitiligo results from a complex interaction of several factors, including genetic, environmental, and immune systems. They all ultimately contribute to the destruction of melanocytes, which result in depigmented lesions. The studies of the genetic epidemiology of vitiligo have led to the recognition that it is part of a more comprehensive, autoimmune, and genetically determined diathesis. Attempts to determine the genes involved in vitiligo exposure have involved gene expression studies and genome-wide linkage analyses in discovering new genes. These studies and more have begun to shed light on vitiligo pathogenesis.
Discovering Genetic Signals
1. A significant number of genes associated with vitiligo genes have been discovered through candidate gene studies and linkage analysis over the past decades.
2. Candidate gene studies are carried out to discover genetic signals representing fairly common fundamental variants with modest effect sizes.
3. While these studies are relatively easy to carry out, they are often subject to false positives. This usually happens because of the differences in ethnicity, insufficient statistical data, case-control analyses, and insufficient correction for several testing both within and across vitiligo studies.
Define the Locus of the Genetic Marker
Genome-wide linkage studies identify vitiligo genetic loci in families. These studies of vitiligo help define the locus of the genetic marker that is inherited with certain diseases. These studies of vitiligo carried out on the Caucasians identify eight suggestive linkages on chromosomes 7, 8, 9, 11, 13, 17, 19, and 22.
Similarly, the studies were also carried out by the Chinese, and linkage signals on chromosomes 1, 4, 6, 14, and 22 were identified. Generally, genetic loci discovered through these studies encompass many megabases. However, the diversity of the proposed regions has made it quite challenging when in fine mapping.
There is NO Vitiligo Gene
Research has shown certain genetic differences between people with vitiligo and those without. And more than 10 genes associated with vitiligo were found. Some of these genes are associated with melanocytes, while others with the immune system. It is important to note that there is no vitiligo gene, which means those people with vitiligo don't have genes that other people don't have.
However, a slightly different protein may be developed, and they may look or act differently than those made by people without vitiligo. And these minor differences may lead to the destruction of melanocytes. Let's look at a few of the identified genes and observe how they may cause vitiligo.
MHC (Major Histocompatibility Complex): These genes play a significant part in the immune system, and they identify cells for the immune system to either attack or pass. For instance, when bacteria infect a cell, MHC releases bits of bacterial proteins on the outer part of the cell – something like a red flag.
When the immune system sees these signs, it attacks the cell, including the bacteria. However, people with an immune system have a slightly different version of these MHC genes. Research shows that there is sometimes something about a melanocyte that MHC sees as a red flag, making the immune system consider it an invader and then attack. And the result is vitiligo.
TYR (Tyrosinase): Tyrosinase makes a protein called TYR, whose function is to pigment melanin in melanocytes. Those with vitiligo have a slightly different version of the TYR gene. Experts think that the immune system attacks melanocytes because TYR looks like an intruder. This is more like a case of mistaken identity that leads to melanocytes destruction, which in turn leads to vitiligo.
On some occasions, a gene in an immune cell trick it to attack the melanocyte, and in another case, the gene in the melanocyte convince the immune system to attack it. Most of the other genes found by scientists act similarly.
MC1R (Melanocortin 1 Receptor): These genes encode the receptor for a melanocyte-stimulating hormone, regular melanogenesis, and associate with hair and skin color. Research shows that MC1R is a significantly marked difference between people with vitiligo and those without it.
NLRP1 (NLR Family Pyrin Domain Containing 1): These genes provide instructions for the production of a protein that is associated with the immune system, helping you regulate the inflammation process. Inflammation occurs due to the immune system reacting to foreign intruders by sending white blood cells and signaling molecules in the areas of disease or injury, facilitating cell or tissue repair. After controlling the issues, the body usually stops the response of inflammatory to prevent damage to its tissues and cells.
PTPN22 (Protein Tyrosine Phosphatase Non-Receptor Type 22): These genes provide instructions for proteins involved in signaling that helps in controlling the activity of the immune system cells known as T cells. These cells identify the foreign bodies in the body and defend against infection.
References
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3521835/
https://www.frontiersin.org/articles/168861#:~:text=Vitiligo%20is%20an%20autoimmune%20disease,association%20studies%20and%20family%20studies.
https://rarediseases.info.nih.gov/diseases/10751/vitiligo
https://vitiligosociety.org/about-vitiligo/
