Identification of shared genetic susceptibility loci for sarcoidosis and tuberculosis

Sarcoidosis and tuberculosis are both complex granulomatous diseases, which mainly affect the lung. The inflammatory processes in the diseases are very similar, suggesting a common etiopathology and most probably also a shared genetic background. In order to identify such shared genetic factors, a combined dataset with imputed Affymetrix 6.0 genome-wide genotype data of a German sarcoidosis cohort and a Ghanaian tuberculosis cohort was analyzed for association. Four different statistical approaches were used to build hypotheses on associated single nucleotide polymorphisms (SNPs), leading to the selection of 53 markers for validation in independent populations. Validation suggested 9 SNPs to be associated of with both diseases with almost equal effect sizes. One variant was identified as a novel potential risk factor specific for tuberculosis. The candidate SNPs will be subjected to replication in additional independent sarcoidosis and tuberculosis populations.