Autoimmune diseases affect up to approximately 10% of the population. While rare Mendelian autoimmunity syndromes can result from monogenic mutations, disrupting essential mechanisms, and peripheral tolerance the more common human autoimmune diseases are complex. These complex disorders arise from the interaction between polygenic risk factors and environmental factors. In the past, genome-wide associated studies have identified loci underlying human diseases, but the causal nucleotide changes and mechanisms are still largely unknown. Learn from Dr. Alex Marson, Sandler Faculty Fellow at the University of California, San Francisco, as he provides insights into his development of a fine-mapping algorithm to identify candidate causal variants for autoimmune diseases from genotyping data.