Chromosomal synteny analyses of regions harboring large orphan gene clusters. Collinear sequences between 3D7 and IPO323 are shown by red segments. Light to dark red shades indicate levels of sequence identity (90 to 100%). Inverted sequences are shown by blue segments, and shades of blue indicate sequence identity (90 to 100%). For each genome, the locations of genes and transposable elements (TE) are shown as independent tracks. (A) A cluster of 12 consecutive orphan genes (ZT3D7_g619 to ZT3D7_g630) located on chromosome 1. An inversion polymorphism affecting 19 kb and 9 genes was located in proximity. The orphan gene cluster was also in proximity to a large TE cluster. (B) On chromosome 5, subtelomeric clusters contained 3 and 12 orphan genes, respectively. Gene ZT3D7_g6501 encodes a peptidase C19. (C) On chromosome 10, a total of 13 orphan genes were clustered with interspersed core genes that have homologs in IPO323. Synteny between 3D7 and IPO323 was interrupted multiple times by nonsyntenic TE clusters.