There is still a significant amount of uncertainty on who gets the disease. The presence of the gene marker HLA-B27 increases your risk of the disease, but only 2% of the population with this gene marker develop the disease. This suggests there are other environmental factors which could contribute to the risk of the disease. These factors could include dysregulation of a gut microbiota, diet, and infections. Further scientific research is underway to provide further answers. In summary, genetic risk factors, along with the environmental triggers, leads to this disease.