pulmonary disorders
Sarcoidosis
Etiology of Sarcoidosis
Sarcoidosis is thought to be due to an exaggerated inflammatory response to an environmental antigen in a genetically susceptible person. Proposed triggers include Propionibacterium acnesand mycobacteria (potentially theMycobacterium tuberculosiscatalase-peroxidase [mKatG] protein) Mold or mildew and certain unidentified substances present in workplaces with musty odors Pesticides, particularly those containing aluminum compounds Tobacco use is inversely correlated with sarcoidosis. Evidence supporting genetic susceptibility includes the following: Higher rate of disease concordance in monozygotic than dizygotic twins Increased prevalence of sarcoidosis (about 3.6 to 9.6%) among 1st- or 2nd-degree relatives of patients who have sarcoidosis Fivefold increase in relative risk of developing sarcoidosis in siblings of patients who have sarcoidosis Identification of several possible human leukocyte antigen (HLA) and non-HLA genes associated with sarcoidosis risk, course, and phenotypes For example the HLA-DRB1*03/DQB1*02 haplotype is associated with Löfgren syndrome and predicts excellent prognosis, in contrast to HLA-DRB1*15/HLA DQB1*0602, which predicts persistent disease. 