Spondyloepimetaphyseal dysplasia with multiple joint dislocations

Abstract

We report four cases of a Spondyloepimetaphyseal dysplasia (SEMD) characterized by joint laxity and large joint dislocations, especially hips and knees. This condition was first reported as a distinct entity by Hall et al., (J Med Genet 1998; 35:566-572). They described three apparently sporadic patients. We present four unrelated patients (three males and one female) with similar radiogiaphic and clinical findings. Usually, this disorder is manifest in the neonatal period by joint dislocations but normal birth length. The children go on to have significant short stature by the time they are toddlers, as well as scoliosis and progressive joint deformities. They have normal psychomotor development. Three of our four patients also had laryngo/tracheomalacia. The radiographic findings include small irregular epiphyses and metaphyseal abnormalities of the long bones. The changes seen on hand x-rays are unique to this form of SEMD and consist of the characteristic finding of gracile metacarpals and the frequent finding of distal ulnar hypoplasia. As the radiographic findings overlapped somewhat with a severe form of multiple epiphyseal dysplasia (MED), mutation detection was undertaken in one proband. This child had normal sequence of previously established MED loci (COMP, exon 3 of COL9A2, exon 3 of COL9A3) as well as exons 8, 9, and, 10 of COL9A1 and COL2A1. Histology of a cartilage sample on this patient was mildly abnormal but not diagnostic. These four cases aid in confirming that SEMD with multiple joint dislocations is a discrete entity which is most likely inherited as an autosomal dominant trait.