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Gaucher disease (GD) is the most common lysosomal disorder and is caused by an inherited autosomal recessive deficiency in β-glucocerebrosidase. This enzyme, like other glycohydrolases involved in glycosphingolipid (GSL) metabolism, is present in both plasma membrane (PM) and intracellular fractions. We analyzed the activities of CBE-sensitive β-glucosidase (GBA1) and AMP-DNM-sensitive β-glucosidase (GBA2) in total cell lysates and PM of human fibroblast cell lines from control (normal) subjects and from patients with GD clinical types 1, 2, and 3. GBA1 activities in both total lysate and PM of GD fibroblasts were low, and their relative percentages were similar to those of control cells. In contrast, GBA2 activities were higher in GD cells than in control cells, and the degree of increase differed among the three GD types. The increase of GBA2 enzyme activity was correlated with increased expression of GBA2 protein as evaluated by QRT-PCR. Activities of β-galactosidase and β-hexosaminidase in PM were significantly higher for GD cells than for control cells and also showed significant differences among the three GD types, suggesting the occurrence of cross-talk among the enzymes involved in GSL metabolism. Our findings indicate that the profiles of glycohydrolase activities in PM may provide a valuable tool to refine the classification of GD into distinct clinical types.

Niemann Pick type C (NPC) disease is an autosomal recessive disorder characterized by the lysosomal/late endosomal (LE) accumulation of unesterified cholesterol and other lipids due to a defect in the intracellular lipid trafficking. About 95% of patients present mutations in the NPC1 gene. Among the 290 mutations reported in the NPC1 gene, about 70% are missense. However, little information is available regarding the impact of missense mutations on NPC1 protein stability and function. In this study, we in vitro characterized the pathogenic effect of 7 NPC1 missense mutations. In all cases, the basal levels of mutant NPC1 expression were reduced with respect to wild type. Treatment of fibroblasts carrying NPC1 missense mutations in homo or hemizygosity, with the proteasome inhibitor MG132 or glycerol 10%, a chemical chaperone known to stabilize misfolded proteins, resulted in a significant increase of NPC1 protein levels in all cell lines, indicating that these mutants are subjected to proteasomal degradation due to protein misfolding The increment of NPC1 mutant protein induced by the proteasome inhibitor was associated with a localization of NPC1 protein within lysosomal/LE compartment. In cell lines carrying mutations p.N1156S, p.L1191F, p.V1165M, and p.I1061T, the increment of NPC1 mutant protein resulted in an improvement of the intracellular trafficking of cholesterol and GM1. These findings showed that it is possible to correct the NPC cellular phenotype by increasing the amount of endogenous NPC1 mutated protein, suggesting that at least some NPC1 mutations might be potentially rescued by small molecules-based chaperone therapy.

Objectives: To assess the association between inherited metabolic disorders and nuchal translucency (NT) measurements., Methods: The NT measurements obtained from 66 fetuses at high risk for metabolic diseases prior to chorionic villus sampling (CVS) were retrospectively analysed., Results: NT was found to be within the normal range in all of the 13 affected fetuses, which included three with Gaucher disease, two with glycogenosis type II, two with mucopolysaccharidosis type I and six others with Krabbe disease, metachromatic leukodystrophy, mucopolysaccharidosis type II, Niemann-Pick A disease, Pelizaeus-Merzbacher disease and sialidosis, respectively. An increased nuchal thickness was found only in one fetus affected with trisomy 21 but not affected with mucopolysaccharidosis type II., Conclusion: NT appears to have a limited role in identifying affected fetuses in pregnancies at high risk for inherited metabolic disorders. NT may be normal in early pregnancy even for fetuses affected with conditions known to be associated with non-immune hydrops fetalis., (2006 John Wiley & Sons, Ltd.)

A prenatal diagnosis of Pelizaeus-Merzbacher disease (PMD) resulting from proteolipid protein gene (PLP) duplication was performed by a quantitative fluorescent multiplex PCR method. PLP gene copy number was determined in the proband, the pregnant mother, the male fetus and two aunts. Small amounts of genomic DNA extracted from peripheral blood and from chorionic villi were used. The fetus, in common with the proband, was identified as PMD-affected being a carrier of the PLP gene duplication, inherited from the mother, while the two aunts were non-carriers. The data obtained were confirmed by segregation analysis of a PLP-associated dinucleotide-repeat polymorphism amplified by the same multiplex PCR., (Copyright 2001 John Wiley & Sons, Ltd.)

Autosomal dominant inheritance of a mild form of osteogenesis imperfecta (osteogenesis imperfecta type I) with different phenotypic expression was found in a family. Phenotypic expression was different for the affected mother and son, in the presence of the same biochemical results. Dermal fibroblast cultures synthesized normal and mutant type I collagen alpha chains. Collagen heterotrimers containing abnormal chains were overmodified along the entire triple helical domain and showed an unusually low denaturation temperature, so far found only in lethal cases. The mild phenotype in the family is probably due to the fact that abnormal type I collagen molecules are more likely to be degraded than utilized in the extracellular matrix.