Mapping eQTLs that affect susceptibility to Tuberculosis
Tuberculosis is a major public health problem. One-third of the population of the world is estimated to be infected with Mycobacterium tuberculosis (Mtb), the etiological agent causing tuberculosis (TB), and active disease kills nearly 2 million individuals worldwide every year. Successions of treatments of TB have quickly become ineffective as the agent rapidly becomes resistant. However, strikingly, only 10% of infected individuals develop the disease. In other words, while Mtb quickly develops resistance to new drugs, roughly 90% of individuals are naturally resistant to infection (when not co-infected by agents, which compromise the immune system, such as HIV). Several lines of evidence indicate that genetic factors contribute to inter-individual differences in susceptibility to TB, including the observation that monozygotic twins have considerably higher concordance rates for tuberculosis morbidity than do dizygotic twins. In addition, multiple rare single-gene mutations with high penetrance have also been linked with susceptibility to mycobacteria. However, although genetic studies of TB have identified important pathways involved in protective immunity, very little is known about the underlying genetic determinants or mechanisms contributing for differences in susceptibility at the population level. Here, we propose to use a combination of empirical and statistical approaches to identify genes and regulatory pathways that contribute to inter-individual and inter-population variability in the immune response to Mycobacterium tuberculosis infection. Specifically, we will study inter- individual variation in the immune transcriptional response of dendritic cells following infection with Mtb, and map the genetic loci that are associated with such variation (eQTLs). To our knowledge, this will be the first genome-wide study of variation in molecular quantitative traits and associated genetic markers that underlie inter-individual variation in immune response to infection with Mtb, and ultimately variation in susceptibility to TB.