INPPL1 (gene that encodes SHIP2) mutated in OPS (MIM 258480). The INPPL1 sequence is accessible as NCBI reference sequence NM_001567.3. SHIP2 domains in the human sequence (1258 amino acids) are shown in Fig. 1. Homozygous or compound heterozygous mutations have been reported in p.E654del(Ho) (97); p.R691W(Ho), p.P659L(Ho), p.T563Gfs*(He), and p.E258Afs*45(Ho) (63); p.F722I(He), p.W688K(He), p.P659S(He), p.T443Ifs*23(He), and p.I616Yfs*14(Ho) (64); and p.Y777*(He) and p.R372Lfs*40(He) (98). So far, most mutations have been shown in the N-terminal and catalytic domain. No mutations have yet to be found in the C-terminal PR and SAM domain. He, heterozygous; Ho, homozygous; OPS, opsismodysplasia; PH-R, PH-related; PR, proline-rich; SH2, Src homology 2.