Definition:

Opsismodysplasia (OPS) is a rare, autosomal-recessive skeletal dysplasia primarily characterized by growth plate defects and delayed bone maturation. Its clinical features are rhizomelic micromelia and facial dysmorphism, including prominent brow, large fontanels, depressed nasal bridge, and small anteverted nose with long philtrum, as well as short feet and hands with sausage-like fingers. Death secondary to respiratory failure during the first few years of life was reported in the cases originally described but the outcome is now known to be highly variable with multiple long-term survivors. Typical radiographical features include short long bones with markedly delayed epiphyseal mineralization, metaphyseal cupping, short metacarpals and phalanges, and severe platyspondyly. Mutations in the gene encoding inositol polyphosphate phosphatase-like 1 (INPPL1) are found in several families with OPS. However, not all patients have INPPL1 variants suggesting that OPS exhibits genetic heterogeneity.