Thesis (Ph.D.) - Cairo University - Faculty of Medicine - Department of Dermatology and Venerology

Background:Alopecia areata (AA) is a common autoimmune disorder that targets anagen hair follicles. The exact pathophysiology of AA remains unknown. The most widely accepted hypothesis is that it is a T-cell{u2013}mediated autoimmune condition that is most likely to occur in genetically predisposed individuals. Concerning the genetic basis of AA; immune genes have been identified as CTLA4 on chromosome 2q33.2, IL2/IL21 on chromosome 4q27, HLA on chromosome 6p21.32. AA preferentially affects pigmented hairs. Finally the role of micro RNA in AA is established in 2017 which can be a possible marker of severity. MicroRNAs (miRNAs) account for 1-5% of the human genome and regulate at least 30% of protein-coding genes. 940 distinct miRNAs molecules have been identified within the human genome. They are a large family of post-transcriptional regulators of gene expression, formed of a class of small, endogenous RNAs of 21{u2013}25 nucleotides in length and are implicated in disease etiology and treatment. Interestingly, miRNAs 31, 155 and 29c have shown an important role in alopecia areata. Since miRNA can be easily detected in different sample types such as tissues, serum, plasma and other body fluids so it can be used as serum biomarker in autoimmune diseases as alopecia areata

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