Heparan sulfate levels in mucopolysaccharidoses and mucolipidoses.

Glycosaminoglycans are accumulated in both mucopolysaccharidoses (MPS) and mucolipidoses (ML). MPS I, II, III and VII and ML II and ML III patients cannot properly degrade heparan sulphate (HS). In spite of the importance of HS storage in the metabolic pathway in these diseases, blood and urine HS levels have not been determined systematically using a simple and economical method. Using a new ELISA method using anti-HS antibodies, HS concentrations in blood and urine were determined in MPS and ML II and ML III patients. HS concentrations were determined in 156 plasma samples from MPS I (n = 23), MPS II (n = 26), MPS III (n = 24), MPS IV (n = 62), MPS VI (n = 5), MPS VII (n = 5), ML II (n = 8) and ML III (n = 3), and 205 urine samples from MPS I (n = 33), MPS II (n = 33), MPS III (n = 30), MPS IV (n = 82), MPS VI (n = 7), MPS VII (n = 9), ML II (n = 8) and ML III (n = 3). The ELISA method used monoclonal antibodies against HS. MPS I, II, III and VII and ML II and III patients had significant elevation in plasma HS, compared to the age-matched controls (p < 0.0001). Eighty-three out of 89 (93.3%) of individual values in the above MPS types and ML were above the mean +2SD of the controls. In urine samples, 75% of individual values in patients with those types were above the mean +2SD of the controls. In contrast to the previous understanding of the HS metabolic pathway, plasma HS levels in all five MPS VI and 15% of MPS IV patients were elevated above the mean +2SD of the controls. These findings suggest that HS concentration determined by ELISA, especially in plasma, could be a helpful marker for detection of the most severe MPS I, II, III, VI and VII and ML II, distinguishing them from normal populations.

Keratan sulphate levels in mucopolysaccharidoses and mucolipidoses.

The mucopolysaccharidoses (MPS) is characterized by accumulation of glycosaminoglycans (GAGs), and mucolipidosis (ML) by accumulation of GAGs and sphingolipids. Each type of MPS accumulates specific GAGs. The lysosomal enzymes N-acetylgalactosamine-6-sulphate sulphatase and beta-galactosidase involve the stepwise degradation of keratan sulphate (KS). Deficiency of these enzymes results in elevation of KS levels in the body fluids and in tissues, leading to MPS IV disease. In this study, we evaluated blood and urine KS levels in types of MPS and ML other than MPS IV. Eighty-five plasma samples came from MPS I (n = 18), MPS II (n = 28), MPS III (n = 20), MPS VI (n = 3), MPS VII (n = 5) and ML (n = 11) patients while 127 urine samples came from MPS I (n = 34), MPS II (n = 34), MPS III (n = 32), MPS VI (n = 7), MPS VII (n = 9) and ML (n = 11) patients. KS levels were determined using the ELISA method. Plasma KS levels varied with age in both control and patient populations. In all age groups, the mean values of plasma KS in MPS and ML patients were significantly higher than those in the age-matched controls. Plasma KS values in four newborn patients were above the mean + 2SD of the age-matched controls (mean, 41 ng/ml). Overall, 85.9% of individual values in non-type IV MPS and ML patients were above the mean + 2SD of the age-matched controls. For urine KS levels, 24.4% of individual values in patients were above the mean + 2SD of the age-matched controls. In conclusion, KS in blood is elevated in each type of non-type IV MPS examined, in contrast to the conventional understanding. This finding suggests that measurement of KS level provides a new diagnostic biomarker in a wide variety of mucopolysaccharidoses and mucolipidoses in addition to MPS IV.