Abstract
Extract: The microchemical study of growth cartilage biopsies may improve the classification and the genetic advice of some types of growth disturbances and contribute to the understanding of biochemical defects.
Small tibial growth cartilage biopsies were performed during orthopedic surgery in cases with achondroplasia, pseudoachondroplasia (three cases), Kniest's disease (two cases), diastrophic dwarfism (two cases), parastrematic dwarfism, pycnodysostosis, mucolipidosis type III, Blount's disease, and in three normal growing children. Five human fetal cartilages were also studied.
The proteoglycans were extracted with 4 M guanidinium chloride. After dialysis against 8 M urea at pH 7, the proteoglycans were obtained by ion chromatography in urea on DEAE-cellulose and submitted to gel electrophoresis on polyacrylamide-agarose gels. The gel electrophoresis of the proteoglycans of growth cartilage of normal growing children gave two metachromatic bands situated close one to another. The proteoglycans extracted from fetal growth cartilage gave a single band with a slightly slower migration. An abnormal gel electrophoretic pattern was found in pseudoachondroplasia and in Kniest's disease. In pseudoachondroplasia a single wide band was found; in overcharged tubes several thin, more rapid bands appeared in addition to the main band. In Kniest's disease three bands were found.
In all of the other syndromes studied two normally or almost normally situated bands were present. Small differences in the width and intensity of the bands observed in several cases were difficult to assess. In all cases except mucolipidosis III and Kniest's disease the collagen was extracted by using limited cleavage and solubilization with pepsin, purified and analyzed by polyacrylamide gel electrophoresis. A type of collagen with a single α band was found.
Speculation: Pseudoachondroplasia and Kniest's disease are due to genetic alterations of proteoglycans. These abnormalities produce the growth disturbance and the skeletal dysplasia. It is likely that the alteration is limited to cartilage or to cartilage and bone. The abnormal endoplasmic reticulum found in both diseases suggests defects in synthesis and/or transfer of proteoglycans or of their precursors. However, the possibility of a different primary defect affecting secondarily the gel electrophoretic pattern of extracted proteoglycans could not be excluded.
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Stanescu, V., Maroteaux, P. Gel Electrophoretic Studies on Proteoglycans and Collagen of Abnormal Human Growth Cartilage: Proteoglycan Abnormalities in Pseudoachondroplasia and in Kniest's Disease. Pediatr Res 9, 779–782 (1975). https://doi.org/10.1203/00006450-197510000-00006
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DOI: https://doi.org/10.1203/00006450-197510000-00006
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