PLP1 and Intellectual disability: A few of those gains serve as pathogenic duplication hotspots, comprising Xp11.22 (Xp11.22 microduplication syndrome; OMIM #300705), Xq21q22 (PLP1 locus; OMIM *300401, Pelizaeus–Merzbacher disease; OMIM #312080), Xq27 (SOX3 locus; OMIM *313430, Mental retardation, X‐linked, with isolated growth hormone deficiency; OMIM #300123), and Xq28 (MECP2 locus; OMIM *300005, Mental retardation, X‐linked syndromic, Lubs type; OMIM #300260) (Gécz et al., 2009).