Short rib polydactyly syndrome

Important diagnostic landmarks :

Severe shortening of limbs leads to the group of lethal chondrodysplasia, i.e. a chondrodysplasia with narrow thorax severe enough to induce neonatal respiratory distress. Lethal chondrodysplasias are often discovered in first or second trimester, and consists of a limited number of disorders.Dominant pattern of narrow thorax, short ribs with polydactyly.Short ribs polydactyly syndrome is part of a spectrum of 4 ciliopathies which includes, for instanceexample, Ellis Van Creveld (EVC) syndrome and Jeune's asphyxiating thoracic dysplasia.EVC shows the same pattern of short ribs + short limbs + postaxial polydactyly, and cardiac defects are a common feature.

However shortening of limbs are less severe and prognosis is not lethal.Jeune's syndrome shows also the same pattern of short ribs + short limbs, however, there is usually no postaxial polydactyly and no cardiac defect.  Prognosis is lethal in most cases.All syndromes part of this spectrum are inherited (non de novo) in an autosomal recessive fashion. This is important for genetic counselling for the next pregnancy.Important general negative signs, important to describe to a dominant pattern, which is key to diagnosis and will lead genetic testing :

• -Normal bone density, no fractures (osteogenesis imperfecta in its early and lethal form).
• -No curved limbs ("telephone handset"), especially femur (thanatophoric dysplasia)
• -No classical widened metaphyses (metatropic dysplasia).
• -No slender, pointy metaphyses, no frontal bossing (achondroplasia)
• -No hitchhiker thumb (diatrophic dysplasia).
• -Pas d’anomalie de minéralisation, ni de fractures (pour une ostéogénèse imparfaite).
• -Normal clavicles, no widened skull sutures (cleidocranial dysplasia)
• -No platyspondyly (COL2A spectrum of chondrodysplasia).