The Pathogenesis of Alopecia Areata
October 1996
in “
Dermatologic Clinics
”
alopecia areata genetic predisposition HLA haplotypes HLA-DR4 HLA-DR5 chromosome 21 Down syndrome cytokines interleukin 1 receptor antagonist gene autoimmunity autoimmune disorders autoantibodies corticosteroids cyclosporin A hair regrowth atopy psychological stress trauma infection immune system dysfunction hair follicle physiology alopecia areata genetic predisposition HLA-DR4 HLA-DR5 Down syndrome cytokines interleukin 1 receptor antagonist gene autoimmunity autoimmune disorders autoantibodies corticosteroids cyclosporin A hair regrowth atopy psychological stress trauma infection immune system dysfunction hair follicle physiology
TLDR Alopecia areata is likely caused by a combination of genetic factors and immune system dysfunction, and may represent different diseases with various causes.
The 1996 document examines the causes of alopecia areata, highlighting genetic predisposition as a key factor, with 10% to 20% of cases having a family history and links to specific HLA haplotypes like HLA-DR4 and DR5. It also notes a genetic component on chromosome 21 due to the association with Down syndrome. The role of cytokines is discussed, with a particular allele of the interleukin 1 receptor antagonist gene being associated with disease severity. Autoimmunity is suggested as a likely cause, with a common co-occurrence with other autoimmune disorders, although the role of autoantibodies is unclear. Treatments that affect the immune system, such as corticosteroids and cyclosporin A, have been shown to stimulate hair regrowth. The document also mentions that alopecia areata can be more severe in individuals with atopy and that psychological stress, trauma, and infection might trigger the condition in genetically susceptible individuals. It concludes that alopecia areata may involve both immune system dysfunction and changes in hair follicle physiology, and it may actually represent a group of diseases with varying causes. Animal models are suggested as useful tools for further research into the genetic basis and treatment of alopecia areata.
