Diagnosis of mucopolysaccharidoses in a clinically selected population by urinary glycosaminoglycan analysis: a study of 2,000 urine samples.

Two thousand urine samples (from patients presenting with clinical features suggestive of a mucopolysaccharidosis, MPS) were analysed by a procedure that included a quantitative measurement of glycosaminoglycan (GAG) hexuronic acids (harmine reagent), a qualitative GAG analysis (cellulose acetate electrophoresis) and a study of urinary oligosaccharide patterns. One hundred and seventy MPS and 29 oligosaccharidosis-affected patients were found, but 23 MPS patients among the 170 would have been missed by use of a quantitative procedure only. Fourteen of these (mainly MPS IV A) were detected on the basis of abnormal electrophoresis and the 9 others on the basis of abnormal urinary oligosaccharide patterns (MPS IV B patients). Our results emphasize that normal quantitative GAG excretion alone cannot rule out a diagnosis of MPS; qualitative analysis is also required, as well as oligosaccharide screening.