Autophagy as an important process in gut homeostasis and Crohn’s disease pathogenesis

Crohns disease (CD) is a complex polygenic trait whereby multiple genetic and non-genetic risk factors contribute to disease susceptibility. Association testing is a statistical approach commonly used for identifying genetic risk factors for complex/multigenic disease, which typically compares the allele frequency of a selected marker, most often a bi-allelic single nucleotide polymorphism (SNP), for differences between patient and control populations. SNPs represent most of the common genetic variation, with an estimated 10 million SNPs found in the human genome.1 Although a powerful statistical approach, until recently the majority of association studies were limited to the examination of a small number of candidate genes, the selection of which will inevitably be biased by the current knowledge of disease pathogenesis. Following some key developments in our understanding of genetic variation within the human genome, as well as technological advances that have enabled affordable genotyping of 300 000–1 000 000 SNPs per study subject (and, therefore, ∼1 billion genotypes or more per genetic study), association testing can now be applied genome wide in order to search for genetic risk factors in an unbiased manner. [...]