Alopecia areata is a/ an -

Ans. is 'a' i.e., Autoimmune disorder Pathogenesis of alopecia areata1. Autoimmunityo Current evidence suggests that alopecia areata is caused by an abnormality in the immune system. This particular abnormality leads autoimmunity. As a result, body's own immune system attacks the hair follicles and disrupts normal hair formations. Autoimmune pathogenesis is supported by -The germinative zones of hair follicles are surrounded by T-lvmphocytes, where they are not normally present.Sometimes alopecia areata is associated with other autoimmune disorders, e.g. vitiligo, IL4, ulcerative colitis, hypothyroidism.# Frequency of type 1 DM is increased in relative of patients with alopecia areata but not in patient themselves --> alopecia areata may be protective against type 1 DM.2. Genetic factorso Besides autoimmunity genetic factors also have pathogenic role10-20% Patients give family historyfThere is polygenic inheritenceStrong association between alopecia areata and MHC class II, i.e. HLA-DR4, HLA DR-5, HLA DQ-3Genetic disorders like autoimmune polyglandular syndrome type I and Down s syndrome have high incidence of alopecia areata.