In addition to this primary analysis, subsets of genetically unrelated individuals were selected from each family-based cohort (i.e. the most severe case in each family, by symptom count, was selected, followed by selection of unrelated/married-in controls) and used to perform a conventional case/control GWAS using logistic regression. This was used in place of the family-based GWAS for estimation of effect sizes and LD score regression analyses (Supplementary Table S2).
