Overview

Introduction Alopecia areata (AA) is a complex inflammatory disease characterized by cellular infiltration of T- lymphocytes targeting hair follicles, disrupting the anagen phase, with spontaneous remission, recurrence, and exacerbation, making it very unpredictable and emotionally disturbing . It affects nearly 1-2% of the general population with a lifetime risk of 2%, The onset of AA might be at any age; however, most patients develop the disease before 40 years of age . Early-onset AA (a mean age of onset at 5-10 years) predominantly presents as a more severe subtype, such as alopecia universalis . Alopecia areata presents clinically as a non-scarring patchy hair loss primarily on the scalp, and/or other hairy areas and may progress to total scalp hair loss (alopecia totalis, AT ) or complete body hair loss (alopecia universalis, AU ) . Approximately 5- 10% of AA patients will progress into AT/AU . The course of AA varies greatly, the strongest predictors of a poor prognosis include AT, AU, or ophiasis pattern hair loss, as well as earlier age of onset . Severe and recurrent AA disturbs quality of life of patients and may also lead to depression, changed self-image,and interferes with social activities . Currently, the hypotheses for AA development mostly focus on the collapse of immune privilege properties of the hair follicles(HFs) and the nature of self-antigen presentation (follicular antigens) that result in the induction and subsequent attack of activated lymphocytes . Activation of the lymphocytes mainly CD8+NKG2D+induces release of severalTh1 cytokines; interleukin (IL)-1α , IL-1β , and tumor necrosis factor (TNF) alpha, capable of inhibiting (HF) growth with early termination of anagen . AA is a polygenic disorder in which several major genes dictate susceptibility to disease, up to 28% of patients report at least one affected family member, monozygotic twins have exhibited similar times of onset and patterns of hair loss.

Genes loci for Human leucocyte antigens (HLA)DRB1 1104 and DQB1 03 are detected in patients with AA. The Janus kinases (JAKs) and signal transducer and activator of transcription (STAT); (JAK/STAT) pathway play an important role in inflammatory processes as they are involved in signaling for over 50 cytokines and growth factors. The JAK/STAT pathway transduces multiple extracellular signals involved in cell proliferation, differentiation, migration, and apoptosis .

The JAK family is constituted by four types of cytoplasmic tyrosine kinases:

JAK1, JAK2, JAK3, and TYK2 . STAT, of which there are seven different subtypes (STAT1, STAT2, STAT3, STAT4, STAT5a, STAT5b, and STAT6) (17), is the other fundamental component of the cascade . After being phosphorylated by JAK, STAT translocates to the nucleus to induce the transcription of specific genes. Alterations in the JAK/STAT pathway have been related to the pathophysiology of atopic dermatitis (AD), vitiligo, and AA.

Eligibility

Inclusion Criteria:

• All types of AA.

Exclusion Criteria:

• 1. Pregnancy . 2. Lactation . 3. Systemic diseases . 4. Dermatological disease as vitiligo , psoriasis , atopy . 5. Patient on skin medication affect hair growth as chemotherapy , antithyroid drugs .