In terms of degree of pulmonary involvement and clinical course of disease, almost no phenotypic similarities between the siblings were detected regardless whether the full-sibling and half-sibling pairs were analyzed together or only the full-sibling pairs were examined. Sibling pairs were not significantly concordant in baseline radiographic stage, changes in spirometry, number of organ systems involved, chest radiograph, or overall clinical assessment over time. The only statistically significant concordance found concerned the need for treatment. Although this concordance was detected in both the full-sibling and half-sibling pair and the full sibling pair groups, the level of agreement was poor (к = 0.14 and к = 0.15, respectively). starlix medication
There are very few previously published reports of phenotypic similarities among siblings, and these are all case reports. Sharma and colleagues reported four siblings with sarcoidosis in which three siblings presented with parotid enlargement and liver involvement. Two of the four siblings had erythema nodosum at presentation. Brennan et al identified 13 siblings of sarcoidosis cases in Ireland and noted no significant difference in the mode of presentation or sex distribution between the sibling pairs and the sarcoidosis patients without an affected sibling. Nas-sif and coauthors described 22 French families in which two or three members had sarcoidosis. Sixteen families were white, and 6 were mixed Caribbean. There was a tendency, especially in monozygotic twins, for the dates of revelation of the disease to be very close to each other, and for the clinical and radiologic features to be similar. Human leukocyte antigen polymorphisms were examined, but the study was vastly underpowered to detect any possible relationships.
The cause of sarcoidosis remains unknown, but it is thought to result from by an interplay between environmental exposures and abnormal host re-sponses. Evidence suggests that the immunologic process that leads to sarcoidosis begins when an antigen is presented to a T-lymphocyte by an antigen-presenting cell via an human leukocyte antigen class II molecule. This induces a T-helper type 1 response, whereby cytokines are released that result in cellular recruitment and granuloma formation. Scandinavian investigators have demonstrated a strong association of a specific class of lung T-cells bearing Va^2,3 T-cell antigen receptors in patients with clinically active sarcoidosis having Lofgren syndrome-type phenotype.