Interest in the transcription function of cohesion proteins heightened when heterozygous mutations NIPBL, the human homolog of Nipped-B, were found to cause the human developmental disease, Cornelia de Lange Syndrome (CdLS; OMIM 122470; Krantz et al., 2004; Tonkin et al., 2004). The gene discussed is BRIP1; the disease is Cornelia de Lange syndrome.