A fluorimetric enzyme assay for the diagnosis of Sanfilippo disease type D (MPS IIID)

4-Methylumbelliferyl-α-N-acetylglucosamine 6-sulphate was synthesized and shown to be a substrate for the lysosomal N-acetylglucosamine-6-sulphate sulphatase (GlcNAc-6S sulphatase). Fibroblasts and leukocytes from 3 different Sanfilippo D patients showed <1% of mean normal GlcNAc-6S sulphatase activity. The enzymatic liberation of the fluorochrome from 4-methyl-umbelliferyl-α-N-acetylglucosamine 6-sulphate requires the sequential action of the GlcNAc-6S sulphatase and α-N-acetylglucosaminidase. A normal level of α-N-acetylglucosaminidase activity was insufficient to complete the hydrolysis of the reaction intermediate 4-methylumbelliferyl-α-N-acetylgluco-saminide formed by the GlcNAc-6S sulphatase. A second incubation in the presence of excess α-N-acetyglucosaminidase is needed to avoid underestimation of the GlcNAc-6S sulphatase activity

Prenatal diagnosis of morquio disease type A using a simple fluorometric enzyme assay

A new fluorogenic substrate, 4 methylumbelliferyl B-D-6-sulphogalactoside, was used for the assay of galactose-6-sulphate sulphatase activity in chorionic villi, cultured villus cells, and amniocytes. The fluorometric assay is much more convenient than the conventional assay using radiolabelled, sulphated oligosaccharides. Both types of substrate were used in the prenatal diagnosis of three pregnancies at risk for Morquio type A disease using amniocytes. These enzyme tests, as well as electrophoresis of glycosaminoglycans in the amniotic fluid, indicated affected fetuses in two pregnancies and a non-affected fetus in one

Applications of a new fluorimetric enzyme assay for the diagnosis of aspartylglucosaminuria

L-Aspartic acid-β-7-amido-4-methylcoumarin is a sensitive and specific fluorogenic substrate for lysosomal glycoasparaginase (aspartylgluco-saminidase). Fibroblasts and leukocytes from 8 patients with aspartylglucosaminuria, showed 1-7% of the mean normal glycoasparaginase activity. Heterozygotes showed intermediate activities. Glycoasparaginase activity in chorionic villi, cultured trophoblasts, cultured amniotic fluid cells and amniotic fluid was readily detectable, indicating that prenatal analysis of aspartylglucosaminuria should be possible with this assay. β-Aspartyl-4-methylumbelliferone was synthesized but this potential substrate can not be used to assay glycoasparaginase since it hydrolyses spontaneously

Glycogenosis type II (acid maltase deficiency)

Glycogen storage disease type II (GSD II/glycogenosis type II/Pompe's disease/acid maltase deficiency) is caused by the deficiency of lysosomal α-glucosidase resulting in lysosomal accumulation of glycogen. The disease is inherited as an autosomal recessive trait and is clinically heterogeneous. Early and late onset phenotypes are distinguished. Insight in the molecular nature of the lysosomal α-glucosidase deficiency and the underlying genetic defect has increased significantly during the past decade. This minireview on GSD II was written at the occasion of The International Symposium on Glycolytic and Mitochondrial Defects in Muscle and Nerve, held in Osaka, Japan, July 1994. It is an update of current literature, but also includes original data from the collaborating authors on mutations occurring in the lysosomal α-glucosidase gene and on prenatal diagnosis by chorionic villus sampling. The genotype–phenotype correlation and the prospects for therapy are addressed

Genotype-phenotype correlation in adult-onset acid maltase deficiency

We performed a clinical, biochemical, and genetic study in 16 patients from 11 families with adult‐onset acid maltase deficiency. All patients were compound heterozygotes and carried the IVS1(– 13T→G) transversion on one allele; the second allele harbored either a deletion of a T at position 525 in exon 2 (7 probands, 64%) or a deletion of exon 18 (1 proband, 9%). Detrioration of handicap was related to age, and decrease in vital capacity to duration of the symptomatic stage. Respiratory insufficiency was never the first manifestation. The levels of activity of serum creatine kinase and of β‐glucosidase in peripheral blood cells or muscle were helpful for the diagnosis, but did not have prognostic value. The adult form of acid maltase deficiency appears to be both clinically and genetically rather homogeneous; decrease of β‐glucosidase activity is the final common pathway leading to destruction of muscle fibers and progression of muscle weakness over a period of years. Copyrigh

β-Mannosidase deficiency: Heterogeneous manifestation in the first female patient and her brother

Summary β-Mannosidase deficiency was demonstrated in fibroblasts of a girl who showed severe psychomotor retardation, bone deformities and gargoylism and recurrent skin and r

The natural course of infantile Pompe's disease: 20 original cases compared with 133 cases from the literature

OBJECTIVE: Infantile Pompe's disease is a lethal cardiac and muscular disorder. Current developments toward enzyme replacement therapy are promising. The aim of our study is to delineate the natural course of the disease to verify endpoints of clinical studies. METHODS: A total of 20 infantile patients diagnosed by the collaborative Dutch centers and 133 cases reported in literature were included in the study. Information on clinical history, physical examination, and diagnostic parameters was collected. RESULTS: The course of Pompe's disease is essentially the same in the Dutch and the general patient population. Symptoms start at a median age of 1.6 months in both groups. The median age of death is 7.7 and 6 months, respectively. Five percent of the Dutch patients and 8% of all reported patients survive beyond 1 year of age. Only 2 patients from literature became older than 18 months. A progressive cardiac hypertrophy is characteristic for infantile Pompe's disease. The diastolic thickness of the left ventricular posterior wall and cardiac weight at autopsy increase significantly with age. Motor development is severely delayed and major d