Alopecia Areata: Genetic and Immunological Insights

The 2017 document discusses Alopecia Areata (AA), an autoimmune condition causing hair loss, and its severe forms, alopecia totalis (AT) and alopecia universalis (AU). It identifies genetic links to immune system genes and pathways, with T-cell activation, JAK-STAT signaling, and viral defense responses being significant. The collapse of hair follicle immune privilege, increased HLA expression, and immune cell infiltration, particularly by CD8+NKG2D+ T cells, are central to AA's pathogenesis. The document also notes altered cytokine levels, suggesting immune imbalance, and the unclear roles of NK cells, mast cells, and macrophages. Interferons, especially IFN-y, and cytokines like IL-2 and IL-15 are implicated in AA. While there are no FDA-approved treatments, JAK inhibitors have shown potential in small patient trials and animal models, but larger studies are needed to confirm their efficacy and safety. The document concludes that understanding the genetic and immunological aspects of AA has been crucial in identifying new therapeutic targets, with JAK inhibitors being a promising avenue for treatment.