Comparison between the biochemical properties of plasma chitotriosidase from normal individuals and from patients with Gaucher disease, GM1-gangliosidosis, Krabbe disease and heterozygotes for Gaucher disease.

OBJECTIVES: The aim of the present work was to establish the range of chitotriosidase (CT) activity in normal individuals (controls), patients with Gaucher disease (GD), GM1-gangliosidosis (GM1), Krabbe disease (KD) and heterozygotes for Gaucher disease (HG). The kinetics of the enzyme in the five groups was also investigated. DESIGN AND METHODS: Plasma CT activity, as well as Km, Vmax, optimum pH and thermal stability of the enzyme was determined in plasma of controls, GM1, KD, GD and HG subjects. RESULTS: CT activity in GD, GM1 and KD patients was, respectively, around 600-fold, 15-fold and 12-fold greater than in normal individuals. There was no significant difference between CT activity in the HG and the control group. We also demonstrated that all CT kinetic parameters evaluated (optimum pH, Km, Vmax, thermal stability) in plasma of GD, KD and GM1 patients were significantly different from those of normal individuals. Regarding to thermal stability, our results show that CT activity in the control group was more stable than in the other groups. CONCLUSIONS: Based on the differences found in the biochemical parameters studied, we presume that the parameters analyzed may be useful in the diagnosis of the Lysosomal Storage Diseases.

Application of a comprehensive protocol for the identification of Gaucher disease in Brazil.

Gaucher disease (GD) is a sphingolipidosis caused by a genetic defect that leads to glucocerebrosidase (beta-glucosidase) deficiency. Between January 1982 and October 2003, 1,081 blood samples from patients suspected of having GD were referred for biochemical analysis. The activities of the enzymes beta-glucosidase (beta-glu) and chitotriosidase (CT) were measured in these samples. Among the 412 diagnosed cases of GD (38.1%), the great majority were GD type 1. The Brazilian regions with the greatest concentration of these patients were the Southeast, South, and Northeast. The mean age of patients at diagnosis was 19 years. The activity of beta-glu in patients with GD was, on average, 10.7% of that of normal individuals. CT was, on average, 269 times more elevated in this group of patients. Among the 669 cases with no confirmation of GD, there were patients with Niemann-Pick disease types A, B, or C (44 cases), possible heterozygotes for GD (59 cases), patients with other lysosomal storage diseases (LSDs) (19 cases) or with other inborn errors of metabolism (3 cases). In 508 cases, no metabolic disorder was found. This study shows that the biochemical protocol employed was effective for the detection of GD, a disease that is reasonably frequent in Brazil.

Biochemical characterization of chitotriosidase enzyme: comparison between normal individuals and patients with Gaucher and with Niemann-Pick diseases.

OBJECTIVES: The aim of the present study was to establish the range of chitotriosidase (CT) activity in normal individuals, patients with Gaucher disease (GD) and Niemann-Pick disease (NPD), types A or B. The kinetics of CT in these three groups was also investigated. DESIGN AND METHODS: CT activity, as well as Km, Vmax, optimum pH, and thermal stability of the enzyme were determined in the plasma of control, GD, and NPD subjects. RESULTS: CT activity in GD and NPD patients was, respectively, around 600-fold and 30-fold greater than in normal individuals. We observed significant differences in optimum pH, Vmax, and thermal stability between the various groups. Km was different in normal individuals relative to GD and NPD patients. However, there was no significant difference between Km values in patients with GD and with NPD. CONCLUSIONS: Based on the differences found in the biochemical parameters studied, our results may be important to help the identification of patients not only with GD but also with NPD.

Biochemical study on beta-glucosidase in individuals with Gaucher's disease and normal subjects.

BACKGROUND: Gaucher's disease (GD) is a disorder caused by the deficiency of lysosomal beta-glucosidase, an enzyme that participates in the degradation of glycosphingolipids. Deficiency of this enzyme results in the accumulation of glucocerebrosides in macrophage lysosomes. No studies comparing the biochemical and kinetic behavior of this enzyme in leukocytes and fibroblasts from normal individuals and patients with Gaucher's disease are available. METHODS: We compared the activities of beta-glu and chitotriosidase between normal subjects and Gaucher disease patients, and characterized the behavior of beta-glu in terms of pH optimum, heat stability, Km and Vmax. RESULTS: The results showed a different behavior of the enzyme in the groups analyzed. CONCLUSIONS: This finding might be useful in cases in which the measurement of enzyme activity alone is not reliable for the establishment of the diagnosis of Gaucher's disease.