RESUMEN
Detection of Portuguese carriers for Gaucher disease with urine samples as a source of enzyme was carried out using an immunological procedure employing an anti-glucocerebrosidase monoclonal antibody and by DNA analysis for the presence of the two glucocerebrosidase mutations most frequently found in Portuguese Gaucher patients. Patients, obligate and putative carriers, and individuals unrelated to patients were analyzed. It was found that the vast majority of carriers for the two tested mutations (N370S and L444P), as well as obligate carriers for as yet unidentified mutations, could be distinguished from control subjects with this relatively easy and economic immunological procedure. Furthermore, results obtained for control subjects suggested a high frequency of carriers for the N370S mutation in the Portuguese population. It is concluded that this procedure may be useful in mass screening for carrier detection prior to DNA analysis, particularly in the study of non-Ashkenazi populations in which a significant number of mutations associated with Gaucher disease remain unidentified.
Asunto(s)
Análisis Mutacional de ADN , Enfermedad de Gaucher/genética , Glucosilceramidasa/genética , Heterocigoto , Adolescente , Adulto , Anciano , Anticuerpos Monoclonales/inmunología , Niño , Femenino , Enfermedad de Gaucher/orina , Genotipo , Glucosilceramidasa/inmunología , Glucosilceramidasa/orina , Humanos , Masculino , Persona de Mediana Edad , PortugalRESUMEN
The feasibility of using urine samples for the identification of patients with Gaucher disease and carriers has been investigated. It was found that the pH of a urine sample should be pH 6.0 or lower to ensure stability of lysosomal hydrolases. Two parameters of glucocerebrosidase, which is deficient in Gaucher disease, were studied using urine samples from control subjects, obligate carriers and patients. Firstly, the relative level of glucocerebrosidase activity was measured by relating the activity of the enzyme to that of another lysosomal hydrolase. Secondly, the enzymic activity of glucocerebrosidase per unit of protein was measured using an immunological method. The first method allowed discrimination of nearly all obligate carriers of type 1 Gaucher disease from normal individuals. The second method allowed clear discrimination of the majority of carriers from normal individuals, but some obligate carriers were not distinguishable from normal subjects on the basis of this parameter. However, the combination of both methods allowed discrimination between all obligate carriers examined so far (n = 34) and controls (n = 86). There was variability between healthy individuals in the relative amount of glucocerebrosidase in urine samples. A small proportion of healthy individuals have a relatively high activity of glucocerebrosidase in urine samples, reminiscent of observations made in white blood cells by other investigators. In urine samples from two unrelated parents of Gaucher disease patients a level of glucocerebrosidase activity was present that could not be distinguished from that in samples of patients. These individuals represent cases with subclinical manifestation of Gaucher disease, illustrating once more the remarkable heterogeneity in clinical expression of this disorder.
Asunto(s)
Enfermedad de Gaucher/enzimología , Tamización de Portadores Genéticos , Glucosilceramidasa/orina , alfa-Glucosidasas/orina , Estabilidad de Enzimas , Enfermedad de Gaucher/diagnóstico , Humanos , Concentración de Iones de Hidrógeno , Hidrolasas/orina , Lisosomas/enzimología , beta-N-Acetilhexosaminidasas/orinaRESUMEN
Human urine contains a soluble form of glucocerebrosidase, an enzyme associated with the lysosomal membrane in cells and tissues. Urinary glucocerebrosidase is identical to the enzyme extracted from tissues with respect to the following parameters: Km for natural and artificial substrates, inhibition by conduritol B-epoxide, and stimulation by taurocholate. The enzyme is greater than 90% precipitable by polyclonal anti-(placental glucocerebrosidase) antiserum. Upon isoelectric focussing of urinary glucocerebrosidase multiple peaks of activity were observed. Partial deglycosylation (removal of sialic acid, N-acetylglucosamine and galactose) of the urinary enzyme increased the isoelectric point to a value identical to that of the main form found after partial deglycosylation of the placental enzyme. Upon polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulphate followed by immunoblotting, the immunopurified urinary enzyme shows the same molecular mass forms as the enzyme immunopurified from brain and kidney. In placenta the apparent molecular mass is somewhat higher but upon removal of sialic acid, N-acetylglucosamine and galactose the urinary and the placental enzyme show identical molecular masses of 57 kDa. We conclude that the enzymes extracted from urine and tissue are identical and that differences in apparent molecular mass and isoelectric point are probably due to heterogeneity in the oligosaccharide moieties of the molecules.
Asunto(s)
Membrana Celular/enzimología , Glucosidasas/orina , Glucosilceramidasa/orina , Placenta/enzimología , Cromatografía Líquida de Alta Presión , Electroforesis en Gel de Poliacrilamida , Ensayo de Inmunoadsorción Enzimática , Humanos , Concentración de Iones de Hidrógeno , Sueros Inmunes , Focalización IsoeléctricaRESUMEN
Glucocerebrosidase is present in considerable amounts in human urine. The enzyme is stable in concentrated urine for several days when stored at 0 degrees C. Like tissue glucocerebrosidase, the urinary enzyme is inhibited by conduritol B-epoxide and hydrolyses not only glucocerebroside but also the synthetic substrate 4-methyl-umbelliferyl-beta-D-glucoside. The enzyme is deficient in urine from patients with Gaucher disease (type 1). It is possible to discriminate completely between patients with type 1 Gaucher disease and control subjects by measuring the ratio glucocerebrosidase/beta-hexosaminidase in urine. The value of this ratio (mean +/- SE) with the synthetic substrates 4-methylumbelliferyl-beta-glucoside and p-nitrophenyl-beta-N-acetylglucosaminide, respectively, was 34.2 +/- 3.7 (n = 24) in the controls and 2.1 +/- 0.9 (n = 21) in the patients.