The genetic basis of alopecia areata

Alopecia areata (AA) is a common autoimmune disorder, characterized by circle patches of hair loss, in which genetic and environmental factors influence the disease development and progression. In this chapter, we will focus on the genetic loci that have been associated with AA. Some of these loci contain genes involved in innate and adaptive immunity and are shared with other autoimmune diseases, suggesting an overlap of the genetic mechanisms involved in the development of such disorders. Linkage and association studies underline the major region of AA susceptibility coming from the HLA system (6p21.32), specifically HLA-DQB1*03 alleles coding for DQ7 heterodimers. Modern technological innovations have advanced our understanding of the genetic basis of AA. Genome wide association studies have recently identified new chromosomal regions linked to AA liability in 2q33.2 (CTLA4), 4q27 (IL-2/IL-21), 6q25.1 (ULBP), 10p15.1 (IL-2RA) and 12q13 (IKZF4). A significant association was also evident for single-nucleotide polymorphisms in 9q31.1 and 11q13, harboring genes expressed in the hair follicle (STX17 and PRDX5, respectively), and in an intronic region of SPATA5 gene. These association studies may provide mechanistic insights into the AA pathogenesis and can improve the predictive models of the genetic risk. Follow-up of individuals with a high genetic risk of AA could also help to elucidate the role of environmental factors (such as stressful events, diet, infections etc) with the general aim to develop novel clinical approaches for AA treatment. © 2012 Nova Science Publishers, Inc.