Here, we explored these relationships using novel engineered mouse models carrying a deletion (Del/+) or a duplication (Dup/+) of the Sult1a1-Spn region homologous to the human 16p11.2 BP4-BP5 locus.     ///     The 16p11.2 600 kb BP4-BP5 deletion and duplication syndromes have been associated with developmental delay. 