Text Box: A VERY RARE FORM OF MUCOPOLYSACCHARIDOSES, b-GLUCURONIDASE DEFICIENCY WITH NORMAL GLYCOSAMINOGLYCAN EXCRETION: A CASE REPORT Ezgü F S, Tümer L, Hasanoğlu A, Biberoğlu G Gazi University, Department of Pediatrics, Ankara, Turkey Objective: b-glucuronidase deficiency is a very rare form of mucopolysaccharidoses. A case with b-glucuronidase deficiency is presented and the importance of chorion villus sampling in prenatal diagnosis is emphasized. Case: A 7-year-old boy had admitted to our hospital for enuresis, difficulty in walking and learning disability. As his physical examination revealed a coarse face, pectus carinatus, genu valgum deformity and mental and motor retardation he was decided to be investigated further for mucopolysaccharidoses in the Pediatric Metabolism and Nutrition Division. Although the quantiative glycosaminoglycan excretion in the urine was found to be normal and x-ray films revealed only spatule cots, thin layer chromatography and electrophoretic investigation of the urine were performed in which chondroitin sulfate excretion was found. The patient was diagnosed to have b-glucuronidase deficiency (MPS Type VII) after the enzymatic analysis which is seen very rarely among the other mucopolysaccharidoses. The mother had been pregnant two months after the diagnosis and chorion villus sampling was performed on the 12nd week. The b-glucuronidase activity was under 2% of the controls and medical abortus was performed. Conclusion: The quantitative glycosaminoglycan excretion in the urine should not always be considered as a reliable diagnostic method in mucopolysaccharidoses and the findings in physical examination should be the main guide for the physician towards diagnosis. 1122