Elevated activity of lysosomal enzymes in amniotic fluid of a fetus with mucolipidosis II (I-cell disease)

Prenatal diagnosis of mucolipidosis type II on first-trimester amniotic fluid

We investigated the possibility of prenatal diagnosis of mucolipidosis type II (ML II) by lysosomal enzyme determination on amniotic fluid obtained at 11 weeks of gestation in three pregnancies at risk. Diagnosis of ML II was made in one case on the basis of increased levels of five lysosomal enzymes tested. The diagnosis was confirmed on cultured chorionic cells, their cultured medium, 17-week amniotic fluid, and fetal plasma obtained for confirmation prior to the termination of pregnancy.

Prenatal diagnosis of I-cell disease in the first and second trimesters

First trimester prenatal diagnosis of I-cell disease (1 case) was based on demonstration of profound deficiency of N-acetylglucosamine 1-phosphotransferase in chorionic villi and in cultured trophoblasts derived from the chorionic villus specimen. Deficiency of this enzyme in cultured amniotic fluid cells obtained via amniocentesis was the basis for prenatal diagnosis of I-cell disease in the second trimester (2 cases). In both procedures, the diagnosis was corroborated by the finding of intracellular deficiency and extracellular elevation of multiple lysosomal enzymes in the fetal cell cultures (trophoblasts and amniotic fluid cells), as well as a significant increase in several lysosomal enzyme activities in the maternal serum.

First trimester prenatal evaluation for I-cell disease by N-acetyl-glucosamine 1-phosphotransferase assay

First trimester prenatal diagnosis was offered to a couple at risk for having a child with I-cell disease (mucolipidosis II). The prenatal evaluation was based for the first time on examination of N-acetylglucosamine 1-phosphotransferase activity, deficiency of which is the primary biochemical defect in both I-cell disease and pseudo-Hurler polydystrophy (mucolipidosis III). Heterozygote levels of this enzyme activity were determined in chorionic villi obtained at 9 weeks of gestation, as well as in cultured trophoblasts derived from this specimen, and led to the diagnosis of an unaffected fetus. This procedure has advantages over that based on detection of abnormal intracellular-extracellular distribution of lysosomal enzyme activities, which is expressed only in homozygotes and fully expressed only in cell culture specimens.

Prenatal diagnosis of inborn errors of metabolism with renal manifestations

Prenatal diagnosis has become increasingly important for the prevention of kidney disease due to inborn errors of metabolism. The indications for prenatal diagnosis in a specific disease depend on the degree of renal involvement and the concomitant pathology of other organs, but especially of the central nervous system. The availability of successful postnatal therapy reduces the necessity for prenatal diagnosis. The determination of enzyme activities, the demonstration of storage products in fetal tissues and the analysis of amniotic fluid components are the biochemical methods most frequently used for prenatal detection. Recently, recombinant DNA techniques have enlarged the spectrum of inherited disorders that can be diagnosed before birth.

Prenatal diagnosis of I-cell disease by measuring altered alpha-mannosidase activity in amniotic fluid

Prenatal diagnoses of I-cell disease were carried out by examination of the amniotic fluid and cultured amniotic cells in four cases of high-risk pregnancy in three different families. Three of the four fetuses were diagnosed as having I-cell disease, on the basis of observation of abnormally increased activity of lysosomal acid hydrolases in the amniotic fluid and their decreased activity in cultured amniotic cells, thus leading to therapeutic abortion. alpha-Mannosidase in the amniotic fluid of the fetuses with I-cell disease exhibited significant alterations in pH profile Km value, thermal stability and isoelectric focusing pattern, compared with the enzyme in normal controls. The results indicate that prenatal diagnosis of I-cell disease may be accomplished by demonstration of altered enzymological characteristics of alpha-mannosidase in the supernatant of amniotic fluid. The significance of the alteration of alpha-mannosidase in the amniotic fluid is not known.

Rapid prenatal diagnosis of GM1-gangliosidosis using microchemical methods

Prenatal diagnoses were established in 3 pregnancies at risk for GM1-gangliosidosis at 9, 10, and 12 days after amniocentesis. Beta-galactosidase activities in cultured amniotic fluid cells were determined by microchemical assays in cell homogenates and in isolated groups of 10--30 freeze-dried cells. The latter method requires only a few hundred cells growing in one or more clones and will usually allow a diagnosis within 9--12 days after amniocentesis.

Prenatal diagnosis of mucolipidosis II (I-cell disease)

A pregnancy at risk for mucolipidosis II (I-cell disease) was monitored in which an affected fetus was predicted on the basis of the analyses of lysosomal hydrolases in amniotic fluid and cultured amniotic fluid cells, and by the demonstration of an excessive accumulation of [35S] sulfate-labeled glycosaminoglycans in cultured amniotic cells. This diagnosis was confirmed by performing enzyme assays and [35S] sulfate incorporation studies on material derived from the aborted fetus.

Prenatal diagnosis of I-cell disease

A pregnancy from a family in risk of I-cell disease was monitored. The fetus was diagnosed as having I-cell disease based on the findings that (1) lysosomal enzyme activities except for acid phosphatase and alpha glucosidase were clearly elevated in amniotic fluid and were reduced in cultivated amniotic fluid cells, and (2) cytoplasmic inclusions were seen in cultivated amniotic cells by phase contrast microscopy. The accuracy of prediction was confirmed by cultured skin fibroblast of the aborted fetus.

Prenatal diagnosis and fetal pathology of I-cell disease (mucolipidosis type II)

Increased activity of several lysosomal hydrolases was demonstrated in amniotic fluid from a fifteenth week pregnancy in which the fetus had I-cell disease. Cultured cells from amniotic fluid had a decreased activity of the same enzymes. The diagnosis of I-cell disease was later confirmed by enzyme assays in cell cultures of fetal skin and by morphologic studies of several tissues from the aborted fetus. Electron microscopic studies of the fetal tissues and cultured fibroblasts had large numbers of typical inclusions of I-cell disease, thus substantiating the diagnosis and intrauterine manifestation of the disease. The results indicate that prenatal diagnosis of I-cell disease is possible with enzyme assays of amniotic fluid and in cultures of fetal cells from the fluid. Enzyme studies of amniotic fluid can provide a preliminary diagnosis within a few hours, but it is suggested that the definitive diagnosis should be based on assays in cultured cells from amniotic fluid.

Levels of lysosomal enzymes in tissues of mice infected with Mycoplasma fermentans

The effects of a toxic dose of Mycoplasma fermentans on levels of lysosomal enzymes in mice were examined. Washed cell suspensions (approximately 10(10) colony-forming units) of a recent isolate of M. fermentans were injected intraperitoneally into 3- to 4-week-old BALB mice, and levels of acid phosphatase and beta-glucuronidase were monitored in liver, spleen, thymus, and serum. Levels of acid phosphatase remained essentially normal, but levels of beta-glucuronidase were markedly evevated in serum and to a lesser extent in liver and thymus. The peak response of serum beta-glucuronidase was noted at 8 h postinjection, with a level of 30 mug of phenolphthalein released per ml per h, representing a six-fold increase over control levels. Pretreatment with BCG did not potentiate the effect as it did with endotoxin. The implication of this increased lysosomal enzyme activity in "lethal toxicity" is that that the increase may be secondary to some other cytotoxic event, or that the affinity of mycoplasmas for biological membranes may be involved. The data suggest that the role of lysosomal enzymes in other models of mycoplasma-induced disease should be evaluated.