Genetic heterogeneity in spondyloepiphyseal dysplasia congenita.

Two unrelated infants seen for evaluation of short stature at 14 and 27 months, respectively, had clinical and radiographic findings consistent with the diagnosis of spondyloepiphyseal dysplasia congenita (SED congenita). No other anomalies were noted. Both sets of parents were normal, both family histories were unremarkable, and neither couple was consanguineous. Both families were counseled that SED congenita is an autosomal dominant disorder and that sporadic cases probably result from new mutations; a low recurrence risk was given. Both families subsequently produced a second affected child. Our experiences suggest that genocopies of autosomal dominant SED congenita exist that are clinically and radiographically indistinguishable, at least within the first 3 years. Autosomal recessive inheritance seems most likely, although alternative explanations are possible. Genetic heterogeneity should be considered when providing genetic counseling for sporadic SED congenita in young children.