a, Burden-contributing variants across cases of the Discovery cohort (n= 102), Replication cohort (n= 175), and Meta-analysis of all BBS cases (n= 277) across four population-based minor allele frequency (MAF) cutoffs (1%, 0.5%, 0.1%, and 0.001%). b, Values of burden-contributing variation between BBS cases of the Discovery cohort (n= 102) and the cohort of NEU controls (n= 384) showing a 2.5-fold enrichment for ultra-rare (MAF < 0.001%) alleles in cases compared to controls. c, BBS cases of the Replication cohort (n= 175) and the Replication control cohort (n= 488) showing a 2.5-fold enrichment for ultra-rare (MAF < 0.001%) alleles in cases compared to controls. d, Collapsed case, control and “non-BBS recessive” cohorts. e, f, Distribution of individuals with burden-contributing alleles with MAF < 1% (e) and with MAF < 0.001% (f) in control individuals (blue bars) and BBS cases (orange bars).