Atypical Hurler syndrome without alpha-L-iduronidase deficiency

A case of type 2 Gm1-gangliosidosis with long survival

An 11-year-old boy with type 2 GM1-gangliosidosis was presented, providing further evidence for the clinical and biochemical heterogeneity of the disease. The patient had several characteristics of type 2 GM1-gangliosidosis, but was different from so-called typical type 2 GM1-gangliosidosis from the point of view of survival and the degree of GM1-ganglioside accumulation. GM1-gangliosidosis was diagnosed by absence of beta-galactosidase activity in leukocytes and the parents had the enzyme levels of heterozygotes. However, the amount of the brain GM1-ganglioside was accumulated to a less degree in comparison with that of typical type 2 GM1-gangliosidosis, though the activity of GM1-beta-galactosidase in the brain was deficient to the same degree as in the typical case.

Neuraminidase activity in liver and brain from patients with I-cell disease

The activity of neuraminidase in liver and brain from I-cell disease (Mucolipidosis II) was investigated. Neuraminidase activities using two substrates [alpha-L-N-acetylneuraminosyl(2 leads to 3)lactose and alpha-L-N-acetylneuraminosyl(2 leads to 6)lactose] were reduced in the supernatant and sedimentable fractions obtained in isotonic KCl. The activity of beta-D-galactosidase was also reduced in the liver; on the other hand, both neuraminidase fractions were normal, although beta-galactosidase activities were markedly reduced. In view of these results, it is suggested that the defect of neuraminidase is not directly responsible for the primary etiology of I-cell disease.

Sphingomyelinase activities in cultured skin fibroblasts from patients with Niemann-Pick Disease

Sphingomyelinase activity in cultured skin fibroblasts from a fetus affected with infantile-type Niemann-Pick disease was 0.5% of control activity; the activities in cells from two patients with adult-type disease (Cases 2 and 3) were 5.0% and 59.0%. Sphingomyelinase activiy was separated into three peaks (I-III) by isoelectric focusing. The isoelectric points were 4.5, 4.9, and 5.2 for peaks I, II, and III, respectively. The three peaks in the Case 2 cells were drastically reduced; only a very small peak could be distinguished (pI of 4.7). On the other hand, three peaks were observed in the Case 3 cells. Peak I had a pI of 4.4, peak II a pI of 4.7, and peak III a pI of 5.2. Peak I was found at near normal level, but both peaks II and III were markedly reduced. Sphingomyelinase in the peak I fraction obtained from isoelectric focusing in Case 3 cells was found to have the same Km value as that in control cells.

Prenatal diagnosis of GM1-gangliosidosis: biochemical manifestations in fetal tissues

A prenatal diagnosis of GM1-gangliosidosis was made in a pregnancy at risk, on the basis of a deficiency of beta-galactosidase activity demonstrated in cultured amniotic fluid cells. Biochemical analyses were performed in the aborted fetus. GM1-ganglioside beta-galactosidase activity was reduced to 1% of the control value in both the brain and liver of the affected fetus. Lamellar bodies suggestive of membranous cytoplasmic bodies were found in cells of basal ganglions, while the accumulation of GM1-ganglioside in the brain was not remarkable.

Lysosomal acid hydrolases in established lymphoblastoid cell lines, transformed by Epstein-Barr virus, from patients with genetic lysosomal storage diseases

Lysosomal acid hydrolases were determined in established lymphoblastoid cell lines, transformed in vitro by Epstein-Barr virus (EBV) from lymphocyte-rich cell populations isolated from the peripheral blood of patients with genetic lysosomal storage diseases--Hurler syndrome, Scheie syndrome, GM1-gangliosidosis type 1 and type 2, Tay-Sachs disease, and I-cell disease--and from obligate heterozygotes for these diseases. The respective enzyme activity was undectectable in lymphoblastoid cells from the patients, but not from controls. Obligate heterozygotes could not always be distinguished from controls in lymphoblastoid cells as well as in leukocytes. These results suggest that established lymphoblastoid cell lines are useful material for the enzymatic study of genetic lysosomal storage diseases.