Alopecia areata

Typical first symptoms of alopecia areata are small bald patches. The underlying skin is unscarred and looks superficially normal. Although these patches can take many shapes, they are usually round or oval. Alopecia areata most often affects the scalp and beard, but may occur on any part of the body with hair. The hair tends to fall out over a short period of time, with the loss commonly occurring more on one side of the scalp than the other. These hairs are very short (), and can be seen surrounding the bald patches. Nails may have pitting or trachyonychia. == Causes ==

Alopecia areata is thought to be a systemic autoimmune disorder in which the body attacks its own anagen hair follicles and suppresses or stops hair growth. It is recognized as a type 1 inflammatory disease. Alopecia areata is not contagious. In addition, alopecia areata shares genetic risk factors with other autoimmune diseases, including rheumatoid arthritis, type 1 diabetes, and celiac disease. It may be the only manifestation of celiac disease. Lifestyle factors such as smoking, sleep quality, and obesity may also contribute to the onset and progression of alopecia areata. Studies indicate that smokers have a higher risk of developing the condition, potentially due to tobacco-induced Th17-mediated inflammation in hair follicles. While some research suggests a link between sleep disorders and alopecia areata, findings remain inconclusive. Additionally, obesity is associated with an increased risk of alopecia areata, likely due to adipokine dysregulation, which promotes chronic low-grade inflammation and alters immune response, as seen in other inflammatory skin conditions. Endogenous retinoids metabolic defect is a key part of the pathogenesis of the alopecia areata. In 2010, a genome-wide association study was completed that identified 129 single nucleotide polymorphisms that were associated with alopecia areata. The genes that were identified include those involved in controlling the activation and proliferation of regulatory T cells, cytotoxic T lymphocyte-associated antigen 4, interleukin-2, interleukin-2 receptor A, and Eos (also known as Ikaros family zinc finger 4), as well as the human leukocyte antigen. The study also identified two genes, PRDX5 and STX17, that are expressed in the hair follicle. There is emerging evidence suggesting a possible link between AA and vaccinations, including influenza, zoster, and human papillomavirus (HPV) vaccines. One possible explanation is that vaccinations could trigger immune system activation, which has been observed to exacerbate preexisting autoimmune or autoinflammatory conditions in at-risk populations. A small study observed hair loss exacerbation in three patients following COVID-19 mRNA vaccinations (Pfizer-BioNTech and Moderna). These patients, who were younger on average (30.6 years) compared to unaffected individuals (37.2 years), experienced worsening hair loss within two weeks post-vaccination. However, AA flares have also been linked to SARS-CoV-2 infection, either as an exacerbation of preexisting disease or a new diagnosis. == Diagnosis ==

Alopecia areata is usually diagnosed based on clinical features. Trichoscopy may aid in establishing the diagnosis. In alopecia areata, trichoscopy shows regularly distributed "yellow dots" (hyperkeratotic plugs), small exclamation-mark hairs, and "black dots" (destroyed hairs in the hair follicle opening). Oftentimes, however, discrete areas of hair loss surrounded by exclamation mark hairs is sufficient for clinical diagnosis of alopecia areata. Sometimes, reddening of the skin, erythema, may also be present in the balding area. • Hair may also be lost more diffusely over the whole scalp, in which case the condition is called diffuse alopecia areata. == Treatment ==

Determining if a treatment is effective is difficult because of spontaneous remission. If the affected area is patchy, the hair may regrow spontaneously in many cases. None of the existing therapeutic options are curative or preventive. For more severe cases, studies have shown promising results with the individual use of the immunosuppressant methotrexate or adjunct use with corticosteroids. When alopecia areata is associated with celiac disease, treatment with a gluten-free diet allows for complete and permanent regrowth of scalp and other body hair in many people, but in others, remissions and recurrences are seen. Deuruxolitinib (Leqselvi) was approved for medical use in the United States in July 2024. Another JAK inhibitor, Ritlecitinib (Litfulo), was approved for medical use in the United States in June 2023. Fecal matter transplants (FMT) have been shown to reverse AA and support hair growth, with long lasting results, even going as far as growing additional hair on arms and face while grey hairs even regained colour. This supports the idea of a connection between gut microbiota having a part in hair loss. Hair transplantation may be an alternative for patients with chronic local alopecia areata. The fact that the disease is autoimmune and progresses with relapses is one of the biggest question marks before surgery. There have been case reports in the literature since the early 2000s. However, in an article published long-term follow-up; It is reported that the hair transplanted to the eyebrow area falls out again due to the recurrence of the disease. A similar situation was not mentioned in previous studies on this subject. Perhaps the long-term follow-ups of other studies were not sufficient. == Prognosis ==

In most cases that begin with a small number of patches of hair loss, hair grows back after a few months to a year. == Epidemiology ==

The condition affects 0.1%–0.2% of the population, with a lifetime risk of 1%-2%, and is more common in females. Alopecia areata occurs in people who are otherwise healthy and have no other skin disorders. Initial presentation most commonly occurs in the early childhood, late teenage years, or young adulthood, but can happen at any ages. Studies indicate that people of Asian descent have the highest risk, with nearly 6 cases per 100 people, compared to fewer than 2 cases per 100 people among White individuals. People living in urban or economically disadvantaged areas face a higher likelihood of developing AA. The effects of the condition also differ by ethnicity: individuals of Black descent with AA are more likely to experience anxiety and require medical leave from work. These findings suggest that genetic, environmental, and social factors may influence both the likelihood of developing AA and its broader personal and professional impact. == Society and culture ==

The term "alopecia", used by physicians dating back to Hippocrates, originates from the Greek word for fox, "alopex", and was so-named due to fur loss seen in fox mange. "Areata" is derived from the Latin word, "area", meaning a vacant space or patch. Alopecia areata and alopecia barbae have been identified by some as the biblical condition that is part of the greater family of skin disorders; the said disorders are purported to being discussed in the Book of Leviticus, chapter 13. Notable people NASCAR driver Joey Logano, obstacle athlete Kevin Bull, politicians Peter Dutton and Ayanna Pressley, K-pop singer Peniel Shin of BtoB, actors Christopher Reeve, Anthony Carrigan, Greg Grunberg and Alan Fletcher, and actresses Jada Pinkett Smith, May Calamawy, and Lili Reinhart all have some form of alopecia areata. Molly Tuttle is a spokesperson for the National Alopecia Areata Foundation. == Research ==

Many medications are being studied. In 2014, preliminary findings showing that oral ruxolitinib, a drug approved by the US Food and Drug Administration (FDA) for bone marrow disorder myelofibrosis, restored hair growth in three individuals with long-standing and severe disease. In March 2020, the US FDA granted breakthrough therapy designation to baricitinib for the systematic treatment of alopecia areata and granted approval in June 2022, It acts as an inhibitor of janus kinase (JAK), blocking the subtypes JAK1 and JAK2. == References ==