It may be the only manifestation of celiac disease.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. 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.A biopsy is rarely needed to make the diagnosis or aid in the management of alopecia areata. Histologic findings may include peribulbar lymphocytic infiltration resembling a "swarm of bees", a shift in the anagen-to-telogen ratio towards telogen, and dilated follicular infundibulae. Other helpful findings can include pigment incontinence in the hair bulb and follicular stelae. Occasionally, in inactive alopecia areata, no inflammatory infiltrates are found. Classification
Commonly, alopecia areata involves hair loss in one or more round spots on the scalp.
Alopecia areata, also known as spot baldness, is a condition in which hair is lost from some or all areas of the body. Often, it results in a few bald spots on the scalp, each about the size of a coin. Psychological stress and illness are possible factors in bringing on alopecia areata in individuals at risk, but in most cases there is no obvious trigger. People are generally otherwise healthy. In a few cases, all the hair on the scalp is lost (alopecia totalis), or all body hair is lost (alopecia universalis). Hair loss can be permanent, or temporary. It is distinctive from pattern hair loss, which is common among males. Alopecia areata is believed to be an autoimmune disease resulting from a breach in the immune privilege of the hair follicles. Risk factors include a family history of the condition. Among identical twins, if one is affected, the other has about a 50% chance of also being affected. The underlying mechanism involves failure by the body to recognize its own cells, with subsequent immune-mediated destruction of the hair follicle.No cure for the condition is known. Efforts may be used to try to speed hair regrowth, such as cortisone injections. Sunscreen, head coverings to protect from cold and sun, and glasses, if the eyelashes are missing, are recommended. In some cases, the hair regrows, and the condition does not reoccur. In others, hair loss and regrowth occurs over years.