The Immunogenetics of Systemic Sclerosis.

Systemic sclerosis (SSc) is a rare disease with a prevalence ranging from 7 to 700 cases per million. Like with most autoimmune diseases, both environmental and genetic factors are involved in the pathogenesis of the SSc. Though the incidence of SSc in the family members of those affected and the concordance rate in twins is very low, inheritance is still the strongest risk factor of SSc. Thus, multiple studies have been conducted to identify the genes responsible for this inheritance including candidate gene association studies and genome-wide analyses. Variations and mutations in the genes encoding cytokines, adhesion molecules, and signaling proteins involved in the interaction between endothelial cells, fibroblasts, and immune cells have been found to be associated with SSc susceptibility. In this chapter, these genes and their contribution to the pathogenesis of the SSc are discussed in detail. These genes are categorized into five major groups of HLA genes, genes involved in the innate immune responses, genes affecting adaptive immune responses, genes with a role in the fibrogenesis pathways, and apoptosis, autophagy, and pyroptosis-related genes.