Ankylosing spondylitis (AS) is a highly heritable disease for which there is a great unmet need for improved therapies. Genetics research has identified several major pathways involved in the disease, from which treatments have either now entered clinical practice or are in development. In particular, therapies targeting the IL-23 pathway were repositioned for use in AS following the discovery of multiple genes in the pathway as determinants of AS risk. Discovery of the association of aminopeptidase genes with AS , and subsequently with psoriasis, inflammatory bowel disease and other conditions, has triggered research into therapies targeting this pathway. The AS -genetic associations point to involvement of gut mucosal immunity in driving disease, and metagenomic studies have provided strong support that AS is a disease driven by interaction between the gut microbiome and host immune system, providing a rationale for the exploration of gut-targeted therapies for the disease.