Making causative connections between genotypic and phenotypic variation is a major challenge for geneticists engaged in the study of human disease. A study drawing this connection for a type 1 diabetes risk locus now demonstrates the importance of focusing on specific quantitative traits and studying them in normal subjects.


Over the last few years, genome-wide association studies (GWAS) have reported an extraordinary harvest of new genetic associations. This productivity has been particularly rich in the area of human autoimmune disorders, where in the aggregate well over 100 confirmed associations have been reported in diseases including type 1 diabetes1, inflammatory bowel disease2 and rheumatoid arthritis, among many others3.