Diagnostic screening for mucopolysaccharidoses by the dimethylmethylene blue method and two dimensional electrophoresis.

BACKGROUND The diagnosis of a mucopolysaccharidosis (MPS) can be achieved by non-enzymatic screening methods, including two-dimensional electrophoresis (2-D EP), and the dimethylmethylene blue (DMB) method. However, the confirmation of MPS diagnosis is difficult to achieve in Taiwan due to the shortage of a well-established MPS diagnostic service. In this article, we introduce the MPS screening protocols we have already established, and also illustrate the interpretation of 2-D EP result for MPS typing determination. METHODS Thirty-seven patients with different types of MPS were analyzed by 2-D EP and the DMB method. They were 4 with MPS I (Hurler), 15 with MPS II (Hunter), 10 with MPS III (Sanfilippo), 5 with MPS IV (Morquio), and 3 with MPS VI (Maroteaux-Lamy). RESULTS The electrophoretic patterns of the affected glycosaminoglycans (GAGs) in different MPS were illustrated, which were the basis of MPS diagnosis. The DMB results showed a significant difference between these diseases, and the dimethylmethylene blue/creatinine (DMB/CRE) ratio of Hunter Syndrome was markedly greater than those of the Sanfilippo, Hurler, and Maroteaux-Lamy Syndrome, successively. The 2-D EP is also applicable for MPS prenatal diagnosis. One cell-free amniotic fluid with suspected Hunter Syndrome was analyzed by 2-D EP, and the results excluded the possibility of MPS which was confirmed by enzymatic study. CONCLUSIONS The 2-D EP provides a good separation of urinary GAG, and the DMB method gives an estimation of the GAG concentration in the urine. Both of the methods are specific, sensitive, and easy to perform for MPS screening and diagnosis.