Abstract
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.
