Vitiligo (Vitiligo) - Genes NLRP1 and PTPN22.
Vitiligo is a disease that causes loss of pigmentation regular. Although it can occur at any age, the average age of onset of the disease is mid-20s and tends to progress over time, growing larger areas of the skin with loss of pigmentation. Some people have also affected areas of pigment loss that affects hair on the scalp or body.
They have identified several forms of vitiligo. Widespread Vitiligo, also called non - segmental vitiligo, which is the most common form involves the depigmentation in skin areas throughout the body. This discoloration typically occurs in the face, neck and scalp, and around the openings of the body such as the mouth and genitals. Sometimes the depigmentation affects the mucous membranes such as the lips. Loss of pigmentation also seen frequently in areas exposed to friction, impact or other trauma, such as hands, arms and bony prominences. Another form of the disease called segmental vitiligo is associated with smaller patches of skin depigmented displayed in a limited area of the body and occurs in about 10% of affected individuals.
Overall, the disease is considered an autoimmune disorder. In individuals with vitiligo, the immune system appears to attack the melanocytes in the skin. About 15% to 25% of people with vitiligo are also affected by at least another autoimmune disorder, such as autoimmune thyroid disease, rheumatoid arthritis, type 1 diabetes, psoriasis, pernicious anemia, Addison 's disease, or systemic lupus erythematosus. In the absence of other autoimmune diseases, vitiligo does not affect the general health or physical functioning.
The development of vitiligo, has been linked to variations in 30 genes. Two of these genes are NLRP1 and PTPN22.
The NLRP1 gene, located on the short arm of chromosome 17 (17p13.2), encodes a member of a family of proteins called nucleotide binding domain and leucine rich repeat containing proteins (NLR). These proteins are involved in the immune system, helping to regulate the process of inflammation. Inflammation occurs when the immune system sends signaling molecules and leukocytes to a site of injury or disease to combat microbial invaders and facilitate tissue repair. The body then inhibits the inflammatory response to prevent damage to its own cells and tissues. The NLRP1 protein is involved in the formation of a molecular complex called inflammasome, which helps trigger the inflammatory process in response to the presence of bacteria or viruses. NLRP1 is likely that the protein may also play a role in apoptosis. Variations in NLRP1 gene have been associated with increased risk of vitiligo. One variation replaces the amino acid leucine by the amino acid histidine at position 155 in the sequence NLRP1 (Leu155His or L155H) protein. This and other variations are likely to affect the activity of the protein, making it more difficult for the body control inflammation and prevent the immune system attacks its own tissues. Although pigment loss associated with vitiligo from the immune system attacks the melanocytes in the skin, it is unclear what specific circumstances trigger the immune system to do so. The disease probably results from a combination of genetic and environmental factors, most of which have not been identified.
The PTPN22 gene, located on the short arm of chromosome 1 (1p13.2), encodes a protein belonging to the PTP (protein tyrosine phosphatase) family. PTP proteins play a role in regulating signal transduction. These signals instruct the cell to grow and divide or to mature and take on specialized functions. The PTPN22 protein is involved in signaling that helps control the activity of T cells immune system. It has been associated PTPN22 R620W variation in the gene with a higher risk of vitiligo. As with other autoimmune disorders, this variation probably affects the activity of the PTPN22 protein, making it more difficult for the body to control the immune system and prevent it from attacking its own tissues. Although pigment loss associated with vitiligo from the immune system attacks the melanocytes in the skin, it is unclear what specific circumstances trigger the immune system to do so. The disease probably results from a combination of genetic and environmental factors, most of which have not been identified.
Vitiligo sometimes occurs in families, but the pattern of inheritance is complex because multiple causal factors are involved. About one fifth of those affected have at least one close relative with the disease.
Tests in IVAMI: in IVAMI perform detection of mutations associated with vitiligo, by complete PCR amplification of the exons of NLRP1 and PTPN22, respectively, and subsequent sequencing genes.
Samples recommended: EDTA blood collected for separation of blood leukocytes, or impregnated sample card with dried blood (IVAMI may mail the card to deposit the blood sample).