“…Consistent with this, Harmston et al (2017) recently reported that clusters of CNEs predict the span of domains, suggesting that CNEs might be involved in chromatin folding. For example, since some UCEs embody enhancer activity (Bejerano et al, 2004; Bhatia et al, 2013; Lampe et al, 2008; McBride et al, 2011; Pauls et al, 2012; Pennacchio et al, 2006; Poitras et al, 2010; Poulin et al, 2005; Sandelin et al, 2004; Vavouri et al, 2007; Visel et al, 2008; War-nefors et al, 2016; Woolfe et al, 2005) and, thus, are likely to participate in enhancer-promoter interactions, might that activity help define chromosomal contacts? Separately, but not exclusively, might selection against changes that disrupt chromosomal domains promote sequence invariance and, thus, ultraconservation?…”