Schematic of the WISP3 protein. Amino acid residue numbers are indicated above each domain. The number of unique mutations and the number of affected families described are indicated below the domains. WISP3 contains a signaling peptide (SP) and four conserved cysteine-rich domains: insulin-like growth factor–binding domain (IGFBP), von Willebrand factor type C module (VWC), thrombospondin domain (TSP), and carboxy-terminal cystine knot–like domain (CTCK). The * indicates where c.156C>A occurs.