A Novel RAB33B Mutation in Smith–McCort Dysplasia


  • Contract Grant Sponsors: Inserm, CNRS, Université Paris Diderot, Fondation Grace de Monaco, DYMension project (contract no. ANR-09-GENO-007 to V.E.G.).

  • Communicated by Mark H. Paalman

Correspondence to: Vincent El Ghouzzi; Inserm U676, Hôpital Robert Debré, 48 blvd Serurier, F-75019 Paris, France. E-mail: vincent.elghouzzi@inserm.fr


Smith–McCort dysplasia (SMC) is a rare autosomal recessive spondylo-epi-metaphyseal dysplasia with skeletal features identical to those of Dyggve–Melchior–Clausen syndrome (DMC) but with normal intelligence and no microcephaly. Although both syndromes were shown to result from mutations in the DYM gene, which encodes the Golgi protein DYMECLIN, a few SMC patients remained negative in DYM mutation screening. Recently, autozygosity mapping and exome sequencing in a large SMC family have allowed the identification of a missense mutation in RAB33B, another Golgi protein involved in retrograde transport of Golgi vesicles. Here, we report a novel RAB33B mutation in a second SMC case that leads to a marked reduction of the protein as shown by Western blot and immunofluorescence. These data confirm the genetic heterogeneity of SMC dysplasia and highlight the role of Golgi transport in the pathogenesis of SMC and DMC syndromes.