The cranio-facial and dental features were studied by means of roentgencephalometry and anthropometry in 24 patients with cartilage-hair-hypoplasia. Data pertaining to the cranial base were considered indicative of subnormal growth in some of the cranial synchondroses. The width of the neurocranium was slightly below the values of the controls, whereas neurocranial length and circumference appeared unaffected. Facial height was larger than in the controls and facial index values were high. The chin was receding, but the other values of facial depth were relatively large. No abnormalities were observed in tooth morphology, dental age, or dental occlusion. The neurocranial morphology in CHH and achondroplasia show some similarities; the skull base, however, is clearly less bent in the CHH-syndrome. This, together with the virtually normal face and dentition in CHH-patients, is, perhaps, of differential diagnostic value.
The Dyggve-Melchior-Clausen (DMC) syndrome includes short stature, dwarfism, mental retardation, and skeletal abnormalities especially in the spine and the extremities resembling the findings in the mucopolysaccharidoses. A particular abnormality is the "lace border" found on radiological examination of the iliac crest. The three original cases have been followed for 15--20 years and the course is characterized by increasing mental retardation and motor disability whereas the "lace border" is less pronounced than before. A survey of 17 other cases is given and similarities and differencies to the mucopolysaccharidoses are pointed out. Patients with the DMC syndrome have been suggested to be deficient in an enzyme cleaving glycoprotein-acid mucopolysaccharide (AMP) linkage. We have previously found in DMC patients, an abnormal excretion of urinary AMP's of which some were undersulfated and some were oversulfated. Lysosomal acid proteinase, i.e., cathepsin D and neutral proteinases: elastase and cathepsin G were found to be normal in DMC patients. However, alfa2-macroglobulin in serum was raised. This increase may cause an inhibition of the neutral proteinases. An increased level of chondroitin sulfate N-acetylgalactosamine-6-sulfate-sulfatase and decreased enzymic levels of aryl sulphatase A and B (assayed with p-nitrocatecholsulfate as a substrate) were found in leucocytes of DMC patients. Metabolic studies have revealed an unbalanced incorporation of glycoprotein AMP-precursors in DMC lymphocytes. All in all the data suggests the DMC syndrome to be an inborn error of glycoprotein-AMP-metabolism.