PTLS-associated duplication types and the STR markers used for the parent-of-origin study. Schematic representation of 17p11.2 and partial 17p12 (centromere-cen, to the right) with LCRs (not to scale). The red horizontal bars depict the portions of the duplicated genomic intervals. LCR-mediated recurrent PTLS duplications: CR duplication between SMS-REPs, uncommon recurrent (Type I, UR1) duplications between LCR17pA and LCR17pD, uncommon recurrent (Type II, UR2) duplications between two LCRs of 24 kb in length. Nonrecurrent (NR) duplications have variable sizes and locations, some of which can have complex structures, for example, the triplicated intervals shown by blue bars. Three nonrecurrent duplications are chosen arbitrarily to represent the 16 NR duplications. The positions of seven STR markers are shown by green arrows.