This includes TRAPPC2, the only subunit associated with skeletal dysplasia (spondyloepiphyseal dysplasia tarda (SEDT); OMIM #313400) [13], and nine other TRAPP subunits (TRAPPC2L, TRAPPC4, TRAPPC6A, TRAPPC6B, TRAPPC9, TRAPPC10, TRAPPC11, TRAPPC12 and TRAPPC14) associated with neurodevelopmental disorders [12,14–24]. This evidence concerns the gene TRAPPC9 and neurodevelopmental disorder.