Whole genome sequence data from 1000 genomes and other sources (http://www.ensembl.org), and the recent human exome paper [135] also reveal the existence of numerous likely loss-of-function alleles, with allele frequencies of 1/1000 or more, within the intracellular tyrosine kinase domain of CSF1R. So, there may be rare/private mutations in CSF1R that impact on IBD susceptibility. Here, CSF1R is linked to inflammatory bowel disease.