The syndrome of caudal dysplasia: a review, including etiologic considerations and evidence of heterogeneity.

The syndrome of caudal dysplasia (CDS) and the wide spectrum of associated skeletal and other anomalies are reviewed, and a further case of this disorder is presented. The syndrome of CDS should be distinguished from the familial forms of sacral dysgenesis, three forms of which are tentatively identified. Two of these usually involve some degree of "hemi-sacrum." The third is usually manifested as partial sacral agenesis with absent distal segments. All these familial types are probably genetic dominants, and none is associated with maternal diabetes. Usually CDS is not familial, but it often is associated with a tendency toward diabetes in the mother. The suggestion is advanced here that CDS is the result of a combination of two principal factors represented by (a) a maternal diabetic tendency and (b) separate nondiabetogenic genes. Determination of the human leucocyte antigen (HLA) haplotypes involved in CDS is suggested to investigate the possibility of genetically distinctive factors in this condition.