MECP2 and Pelizeaus-Merzbacher spectrum disorder: In MECP2 duplication syndrome (MIM 300260) at Xq28 [93, 94] and Pelizaeus-Merzbacher disease (MIM 312080) due to increased PLP1 copy number at Xq22 [94–96], specific CGRs account for up to 30% of the pathological SVs.