baal-nf identifies motif-disrupting variants that decrease transcription factor binding affinity

Human traits vary in part due to genetically-determined change of transcription factor binding affinity within gene regulatory regions. However, few trait-causal variants or mechanisms are known. Here we propose 1,935 variants as strong candidates for causally altering human traits. We discover these through baal-nf which uses chromatin immunoprecipitation-sequencing data to identify allelic imbalance at heterozygous sites for affinity-concordant positions within transcription factor- and co-factor binding motifs. These allele-specific binding sites are evolutionarily conserved and enriched for trait and gene expression associations. baal-nf and these high-quality allele-specific binding sites allow trait variation due to altered transcription factor binding to be investigated.