You might have seen them, crossing the street or buying groceries next to you. Recorded as affecting 0.5-1% of the general population, women and men alike, Vitiligo is a pigmentary skin condition wherein affected individuals develop milky-white patches on their body, due to progressive loss of melanin pigment in their body.
What we know is quite patchy
You probably know it’s called “autoimmune disease”. Let us learn how it is caused, shall we? Disrupted signaling of proteins leads to the destruction of the body’s own cells, i.e., the melanocytes, by the immune system. However, one of the most well-accepted theories is that vitiligo may occur due to multiple mechanisms such as autoimmunity, neural dysfunction, infections, genetic deficiency, and more. Environmental factors such as stress, trauma, free radical exposure, and toxin build-up could aggravate pathology in susceptible individuals. Internal changes in cellular repair, epidermal turnover, and regeneration can be a root cause of dermatological issues such as vitiligo. Studies show that vitiligo patient samples exhibit increased levels of hydrogen peroxide and reactive oxygen species (ROS), which is a hallmark for impaired antioxidant defense.
Spotting the (a)chromatic
Vitiligo does not just cause reduced color or skin patches. There are several forms of this disorder, reported in mild to clinically severe cases. A common manifestation is physical discoloration seen in skin and hair follicles. However, a detailed classification of vitiligo cases looks like this:
- Generalized (common) vitiligo (GV) with symmetrical, bilateral patches or lesions, typically on the hands and face. Larger body parts can develop GV too, if exposed to external trauma.
- GV can progress to universal vitiligo in adulthood, wherein up to 80% of the body surface is affected with lesions.
- Less common forms such as acrofacial and mucosal vitiligo have been documented too. The former affects the digital extremities, face, head, fingers, and the feet. The latter develops in the mucosae of the mouth and genital areas.
- While the above forms are grouped under Non-Segmented Vitiligo, the disease can develop in children in either one (such as the midline) or different segments of the body. This is called Segmented Vitiligo and is seen in 10% of vitiligo cases.
DNA colors the dermis
There are more than fifty genetic regions which have been linked with vitiligo susceptibility and development. Results from genomic studies show that there are common genes which cause (or increase the risk for) inflammatory and autoimmune diseases. Rheumatoid arthritis, psoriasis, lupus, and Addison’s disease may coexist in people suffering from vitiligo.
- Genes that produce cytokines (such as interleukins and tumor necrosis factors) and that regulate melanocortin pathways are among the top candidates. Increased expression of cytokine proteins is observed in the skin cells (lesions) of vitiligo patients. Another important finding is that the 𝞪-MSH (Melanocyte Stimulating Hormone-alpha) is present in lower levels in vitiligo lesions, which means there is reduced binding to the stimulation of melanin production by the melanocortin-1-receptor (MC1R).
- Genetic variation in the in the Major Histocompatibility Complex (MHC) locus (class I, II, III peptides), FOXP1 (forkhead box P1 for lymphoid cell development), TYR (tyrosinase enzyme for melanin biosynthesis) and RERE (regulates apoptosis).
- Tumour Necrosis Factor-alpha (TNF-𝞪), is an important regulatory cytokine that has been implicated in many autoimmune mechanisms, including those of vitiligo. Macrophages, T-cells, and fibroblasts secrete TNF-𝞪, which mediates inflammatory, apoptotic, and immune pathways.
Familial studies have established a significant genetic component and polygenic inheritance for vitiligo. First-degree relatives such as children and siblings have up to 20 times the likelihood of manifesting the disease, at an earlier age (average onset for vitiligo is 20-30 years). Given the shared physiology, affected families may have cases of not just vitiligo, but other related disorders. Inter-individual variation in disease morphology and physical symptoms has been attributed to genetic architecture in different populations. Some Indian studies reported 46% heritability for vitiligo, which confirms its genetic influence.
Care is not just cosmetic
- Treatment for vitiligo ranges from topical applications such as customized make-up, corticosteroid creams, immunosuppressant formulations to phototherapeutic techniques such as UV- and monochromatic light based irradiation.
- Another physical technique is dermal pigmentation also known as micropigmentation. This camouflages the affected areas by micro insertion of pigment into the dermis.
- Surgical intervention by punch grafting is done for patients who do not benefit from standard therapy and are “stable”, i.e., have not reported disease progression in the last 1-2 years.
- Oral administration of antioxidants (e.g., Gingko Biloba extract, zinc, and vitamin supplementation) is also recommended.
- Due to the stark representation on their body, people affected with vitiligo may experience considerable emotional stress, especially in severe cases. This calls for psychological counseling and behavioral therapy.
About the author
Rasika is the product specialist and scientific liaison for Mapmygenome’s personal genomics portfolio. With eight years of experience in sequencing, molecular biology, genetic data analysis and reporting, she currently works in the product team at Mapmygenome. Her key responsibilities include genomics product development, data curation, scientific content creation and management, data analysis and technical support for business development. Her key strength is a robust understanding of consumer genomics, including specialized areas such as pharmacogenomics, nutrigenomics and sports genomics. Rasika is also a certified group fitness trainer and Pilates (Balanced Body) Mat instructor.
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Genetic test for vitiligo
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