The Immunogenetics of Morphea and Lichen Sclerosus

Morphea and lichen sclerosis et atrophicus (LSA) are two distinct immune-mediated diseases with a dominant presentation of dermal fibrosis and sclerosis. The two diseases have many similar clinical and histological features and tend to co-occur. Both diseases are thought to result from a derailment of the normal response to environmental triggers. Positive family history is more common in LSA than morphea but individuals with morphea have a higher frequency of concomitant and familial autoimmunity. These findings hint at the involvement of inheritance in susceptibility to LSA and morphea and thus provide a rationale for exploring the disease genetics. This chapter contains a comprehensive review of the pathogenesis of the two diseases and their known genetic associations including HLA class I and II genes.