Interestingly also, mutations in CTCF, another gene encoding a MER41 LTR-binding TF, are causally linked to “Mental retardation, autosomal dominant 21,” a developmental disorder characterized by significantly below-average general intellectual functioning associated with impairments in adaptive behavior (Gregor et al., 2013). The gene discussed is TF; the disease is CTCF-related neurodevelopmental disorder.