Rough endoplasmic reticulum abnormalities in a patient with spondyloepimetaphyseal dysplasia with scoliosis, joint laxity, and finger deformities.
Iliac crest growth cartilage biopsy in spondyloepimetaphyseal dysplasia (SEMD) showed an endoplasmic reticulum storage disorder of epiphyseal and physeal chondrocytes. Biochemical analyses of iliac crest cartilage extracellular matrix showed no signs of deficits in any of the structural collagens types II, IX, or XI. The physis was abnormal by light microscopy with chondrocyte columnation replaced by clone-like cell accumulations surrounded by widened acellular cartilage septae. The rough endoplasmic reticulum (RER) of most chondrocytes was dilated. In some cells the RER contained homogeneous material but in most there were abnormal electron-dense accumulations. In some the material was seen in small amounts adjacent to the edge of the RER. In others, increasingly large amounts were seen that were randomly oriented and diffusely marginated. In many cells, assembly had progressed to well-marginated collections of wavy rod-like structures with a circular orientation parallel to the outer edges of the RER. The electron-dense accumulations measured from 34 to 40 nm in diameter. Mutations have prevented normal processing of collagen such that exit from the RER is abnormally slowed and abnormal self-assembly occurs within the dilated cisternae.
Shapiro
Frederic
F
Department of Orthopaedic Surgery, Children's Hospital Boston, 300 Longwood Avenue, Boston, MA 02115, USA. frederic.shapiro@childrens.harvard.edu
Mulhern
Howard
H
Weis
Mary Ann
MA
Eyre
David
D
D002356:Cartilage / Q000473:pathology; D002648:Child; D019902:Chondrocytes / Q000648:ultrastructure; D018870:Endoplasmic Reticulum, Rough / Q000648:ultrastructure*; D005260:Female; D005385:Fingers / Q000002:abnormalities* / Q000000981:diagnostic imaging; D006801:Humans; D016916:Joint Deformities, Acquired / Q000000981:diagnostic imaging / Q000473:pathology*; D007593:Joint Instability / Q000000981:diagnostic imaging / Q000473:pathology*; D007719:Knee Joint / Q000000981:diagnostic imaging; D046529:Microscopy, Electron, Transmission / Q000379:methods; D010009:Osteochondrodysplasias / Q000000981:diagnostic imaging / Q000473:pathology*; D011859:Radiography; D012600:Scoliosis / Q000000981:diagnostic imaging / Q000473:pathology*; D013577:Syndrome