TRAPPC2 and osteoarthritis: X-linked spondyloepiphyseal dysplasia tarda (X-linked SEDT) is an X-linked skeletal dysplasia typically affecting male subjects.[1] X-linked SEDT is a rare cause of childhood short stature characterized by defective structures of vertebral bodies and/or of epiphyses of the long bones, leading to short trunk and precocious osteoarthritis.[2] Trafficking protein particle complex subunit 2 (TRAPPC2) is the causative gene, encoding a 140-amino acid protein called transport protein particle complex subunit 2 (TRAPPC2).