Opsismodysplasia (OPSMD; MIM 258480) is an autosomal recessive chondrodysplasia caused by mutations in the inositol polyphosphate phosphatase-like 1 gene (INPPL1).  It is generally non-lethal, and is characterized by severe delay in skeletal ossification, short limbs, small hands and feet, severe platyspondyly with hypoplastic vertebral bodies, metaphyseal cupping, squared iliac bones, horizontal acetabular roofs, hypoplastic ischia and pubis. Additional clinical features include narrow, bell shaped thorax, macrocephaly with large fontanelles, frontal bossing, short nose with anteverted nostrils and depressed nasal bridge, long philtrum and abnormally shaped ears. Schneckenbecken dysplasia (MIM 269250) clinically overlaps with OPSMD and it can be caused by mutations in the SLC35D1 or INPPL1 genes. It is an autosomal recessive perinathal lethal chondrodysplasia. The most characteristic radiological finding in Schneckenbecken dysplasia is small ilia with a snail-like appearance.  Primary differential diagnoses include achondrogenesis, type 1A (ACG1A; MIM 200600), metatropic dysplasia (MIM 156530) and thanatophoric dysplasia, type I and II (TD1; MIM 187600 and TD2; MIM 187601). INPPL1 is a phosphatase involved in the regulation of phosphoinositides. INPPL1 also seems to act as a noncatalytic docking protein for cytoskeletal adhesion proteins, phosphatases and tyrosine kinase-associated receptors.