Tight linkage between type III Gaucher's disease (Norrbottnian type) and a MspI polymorphism within the gene for human glucocerebrosidase

A MspI polymorphism was detected in the beta-glucocerebrosidase gene in 10 Swedish families affected by type III Gaucher's disease. The sizes of the polymorphic fragments were 1.70 and 1.75 kb and the disease was found to segregate with the 1.70-kb fragment in 32 meioses. Only the 1.75-kb fragment was detected in families with no history of Gaucher's disease. The results indicate that the mutation causing type III Gaucher's disease has occurred once within the Swedish population. The polymorphism is useful for carrier detection since biochemical tests sometimes give inconclusive results.

Gaucher disease type 1: cloning and characterization of a cDNA encoding acid beta-glucosidase from an Ashkenazi Jewish patient

Gaucher disease (GD) type 1 is the most prevalent lysosomal storage disease and the most prevalent genetic disease among the Ashkenazi Jews. The defective activity of acid beta-glucosidase is the enzymatic basis of GD and is inherited as an autosomal recessive trait. To investigate the genetic basis of Ashkenazi Jewish GD type 1, a cDNA encoding acid beta-glucosidase was isolated from a cDNA library constructed using splenic poly(A)+RNA from a patient. The cDNA was sequenced to identify mutations, and the presence of a single missense mutation in the patients' genome was confirmed by selective oligonucleotide hybridization and by restriction endonuclease digestion analyses of amplified genomic sequences. This G----A transition (Arg-119 to Gln-119) was present heterozygously in the index patient and his affected third cousin but was not present in normal non-Jewish individuals. This mutation is the second single base mutation found in Ashkenazi Jewish GD type 1 patients. Furthermore, results obtained with the affected third cousin suggest that at least three mutant alleles may be present in this GD subpopulation.

Intrafamilial clinical variability of type 1 Gaucher disease in a French-Canadian family

Glucocerebroside beta-glucosidase (glucocerebrosidase) activity was determined from peripheral blood lymphocytes and cultured skin fibroblasts of eight full sibs in a French-Canadian family at risk for Gaucher disease, an autosomal recessive sphingolipidosis resulting from deficient glucocerebrosidase activity. The diagnosis of type 1, non-neuronopathic Gaucher disease was made in all of the five affected sibs on the basis of deficient (7.5 to 15.5% of control mean) glucocerebrosidase activity and absence of neurological involvement. Normal levels of enzyme activity were found in two of the three asymptomatic sibs. The third asymptomatic sib had an intermediate level (about 50% of control mean) of fibroblast and lymphocyte glucocerebrosidase activity, indicating that he is a carrier. Considerable clinical heterogeneity was noted among the five affected sibs. One patient is mildly affected and so far has not developed any orthopaedic complications associated with Gaucher disease. His haematological complications were also reversed after splenectomy 24 years ago. In contrast to this mild presentation, the patient's splenectomised sister has been very anaemic and thrombocytopenic. There have been severe orthopaedic complications associated with Gaucher disease, including vertebral compression, avascular necrosis, and pathological fracture of the long bones. The clinical picture of the other three affected sibs appeared to vary between the two extremes. Although the asymptomatic parents of the patients died many years ago, their heterozygous status with respect to Gaucher disease can be deduced by the presence of Gaucher homozygotes, normal homozygotes, and one heterozygote among their eight offspring. Present findings suggest that the clinical variability of type 1 Gaucher disease may be attributed to variable expressions of the same Gaucher mutant alleles, in addition to the presence of multiple mutant alleles that are widely disseminated in the population.

Genetic heterogeneity in type 1 Gaucher disease: multiple genotypes in Ashkenazic and non-Ashkenazic individuals

Nucleotide sequence analysis of a genomic clone from an Ashkenazic Jewish patient with type 1 Gaucher disease revealed a single-base mutation (adenosine to guanosine transition) in exon 9 of the glucocerebrosidase gene. This change results in the amino acid substitution of serine for asparagine. Transient expression studies following oligonucleotide-directed mutagenesis of the normal cDNA confirmed that the mutation results in loss of glucocerebrosidase activity. Allele-specific hybridization with oligonucleotide probes demonstrated that this mutation was found exclusively in the type 1 phenotype. None of the 6 type 2 patients, 11 type 3 patients, or 12 normal controls had this allele. In contrast, 15 of 24 type 1 patients had one allele with this mutation, and 3 others were homozygous for the mutation. Furthermore, some of the Ashkenazic Jewish type 1 patients had only one allele with this mutation, suggesting that even in this population there is allelic heterozygosity. These findings indicate that there are multiple allelic mutations responsible for type 1 Gaucher disease in both the Jewish and non-Jewish populations. Allelic-specific hybridization demonstrating this mutation in exon 9, used in conjunction with the Nci I restriction fragment length polymorphism described as a marker for neuronopathic Gaucher disease, provides a tool for diagnosis and genetic counseling that is approximately equal to 80% informative in all Gaucher patients studied.

Gaucher disease

Gaucher disease is a glycolipid storage disorder characterized by accumulation of glucocerebroside in the liver, spleen, and bones, and caused by a deficiency of glucocerebrosidase. Glucocerebrosidase cDNA has been cloned and sequenced, and much has been learned about the synthesis and processing of this enzyme. Inherited as an autosomal recessive disorder, Gaucher Disease is relatively common among Ashkenazi Jews. In its most common form, designated Type 1 or adult type of Gaucher disease, the central nervous system is spared. Several organ systems may be involved, including not only the hematopoietic tissues and bones, but also the lungs. Diagnosis can be achieved without marrow examination by estimating the glucocerebrosidase (beta-glucosidase) activity of the peripheral blood leukocytes. Currently available conventional therapy is purely symptomatic in nature, including orthopedic procedures and splenectomy. On an experimental basis, splenectomy may be partial instead of total. Because the disease is due to an abnormality of the monocyte-macrophage system, cells that arise from the hematopoietic stem cell, and because the central nervous system is spared it has been considered a very suitable candidate for experimental therapeutic intervention. Bone marrow transplantation has been attended with limited success, enzyme therapy has not yet been successful, and studies utilizing gene transfer are underway.

The human glucocerebrosidase gene has two functional ATG initiator codons

Gaucher disease is due to a deficiency in the activity of the enzyme glucocerebrosidase. Glucocerebrosidase is a lysosomal enzyme that presumably requires a signal peptide for transport across the membrane of the rough endoplasmic reticulum and glycosylation for transport into lysosomes. Human glucocerebrosidase cDNA contains two potential ATG start codons in its long open reading frame. The signal peptides that are initiated from each ATG are quite different in their hydrophobicity. We demonstrate that either ATG can function independently to produce active glucocerebrosidase enzyme in cultured fibroblasts. The glucocerebrosidase activity produced from translation products initiated at either ATG is found predominantly in the lysosomes.

Gaucher disease: accurate identification of asymptomatic French-Canadian carrier using nonlabeled authentic sphingolipid substrate N-palmitoyl dihydroglucocerebroside

Gaucher disease is an autosomal recessive sphingolipidosis associated with deficient glucocerebroside beta-glucosidase activity. It is a panethnic metabolic disorder, but the carrier frequency is particularly high among Ashkenazi Jews (estimated between 1:12-1:25). In order to establish a reliable and convenient biochemical assay method for differentiating asymptomatic Gaucher carriers from normal individuals, glucocerebroside beta-glucosidase activity was determined in peripheral blood lymphocytes and cultured skin fibroblasts of 11 Gaucher obligate heterozygotes using the authentic nonlabeled sphingolipid substrate N-palmitoyl dihydroglucocerebroside and the artificial fluorogenic substrate 4-methylumbelliferyl-beta-D-glucopyranoside (4MUGP). The level of lymphocyte beta-glucosidase activity on the glucocerebroside substrate was observed to range from 42-65% of that of the control mean, and there was no overlap of enzyme activity between the Gaucher heterozygotes and controls. However, when the artificial fluorogenic substrate 4MUGP was used, the level of beta-glucosidase activity in 2 of the Gaucher obligate heterozygotes was noted to overlap with that of the control individuals. Contrary to findings in the lymphocytes, cultured skin fibroblasts appear to be a reliable enzyme source for Gaucher carrier detection even when the artificial fluorogenic 4MUGP substrate was used, as the level of beta-glucosidase activity in all of the Gaucher obligate heterozygotes tested was intermediate and distinctly separated from that of the control persons. Using the lymphocyte glucocerebroside beta-glucosidase assay and fibroblast 4MUGP beta-glucosidase assay methods, we identified the carrier status in 3 other relatives and ruled it out in 4 others. These data suggest that nonlabeled glucocerebroside is a reliable and highly specific substrate for either lymphocyte or fibroblast beta-glucosidase activity assay in identifying asymptomatic Gaucher carriers. Use of the 4MUGP substrate for differentiating Gaucher heterozygotes from control persons, on the other hand, should be restricted to the fibroblast enzyme assay method, as considerable overlap of enzyme activity was noted in lymphocytes.

Efficient in vitro and in vivo expression of human glucocerebrosidase cDNA

A human glucocerebrosidase cDNA clone was isolated from a human chronic myelogenous leukemia (line K562) cDNA library using a 36-nucleotide-long synthetic probe (GC-36). The 2.4-kb cDNA contains 184 bp of 5' nontranslated sequences, the complete coding region, and 546 bp of 3' nontranslated sequences followed by 100 bp of poly(A). A primer extension experiment indicated that the cDNA is at least 51 bp shorter than the mRNA at the 5' end. In normal human placenta as well as in fibroblasts from Gaucher's disease patients, a major mRNA species of 2.6 kb hybridizes with the cDNA probe. The amounts of the glucocerebrosidase mRNA in normal placenta and Gaucher's cells are comparable. The cDNA was linked to the SP6 promoter and transcribed in vitro. The resultant RNA, when translated in a cell-free system, yielded a polypeptide of 55 kD, which is the size expected from the coding sequence. The cDNA was inserted into an SV40 shuttle vector, under the transcription control of the SV40 early promoter. COS-M6 cells were transfected with this construct and the biological activity of the cDNA was assayed by monitoring the increase in glucocerebrosidase activity, using 4-methyl umbiliferyl glucopyranoside as a substrate. There was a two- to three-fold increase in enzymatic activity in the transfected cells, compared to nontransfected cells. These results prove the authenticity of the glucocerebrosidase cDNA and provide the basis for experiments to understand the nature of the genetic alterations responsible for Gaucher's disease.

A mutation in the human glucocerebrosidase gene in neuronopathic Gaucher's disease

To search for a genetic marker for type 2 Gaucher's disease (acute neuronopathic form), we compared the nucleotide sequence of a cloned glucocerebrosidase gene from a patient with Gaucher's disease with a normal gene. We found only a single base substitution (T----C) in exon X. This mutation results in the substitution of proline for leucine in position number 444 and produces a new cleavage site for the NciI restriction endonuclease. We analyzed NciI enzymatic digests of genomic DNA from 20 patients with type 1, 5 with type 2, and 11 with type 3 Gaucher's disease, and 29 normal controls for a restriction-fragment-length polymorphism (RFLP). Four of 5 patients with type 2 disease and all 11 with type 3 disease had at least one allele with the mutation. Two of 5 patients with type 2 disease and 7 of 11 with type 3 were homozygous for this mutation. Only 4 of 20 patients with type 1 Gaucher's disease had the mutant allele and were heterozygous for it. None of the 29 normal controls had the mutant allele. The high frequency of this mutation (444leucine----proline) in patients with neuronopathic Gaucher's disease, detectable by the NciI RFLP, may be of value in the identification of patients who will have the neurologic sequelae of Gaucher's disease.

Gaucher's disease in the Cape coloured population of the RSA, including a family with 5 affected siblings

Nine Cape Coloured children from 4 families with severe non-neuropathic Gaucher's disease are documented. The diagnosis was confirmed histologically in the bone marrow, spleen and liver, and by serum acid phosphatase and leucocyte beta-glucosidase assays. This represents a minimum prevalence for Gaucher's disease of 1 in 247,350 in this population and an approximate genetic carrier rate of 1 in 230 for the abnormal gene. A family with 5 affected siblings is recorded. The severe early clinical expression documented in these coloured patients is similar to that described in the Afrikaner population and differs from the less severe expression of Gaucher's disease in the South African Ashkenazi Jewish population. Gaucher's disease in the Cape Coloured population presents with a precocious onset, causes severe complications and progresses rapidly.

Gaucher disease: genetic heterogeneity within and among the subtypes detected by immunoblotting

The genetic heterogeneity of Gaucher disease subtypes and variants was investigated by immunoblotting of fibroblast extracts. For these studies polyclonal and monoclonal antibodies were raised to acid beta-glucosidase preparations containing a single N-terminal amino acid sequence that was colinear with that encoded by the beta-Glc cDNAs. Three forms (Mr approximately equal to 67,000, 64,000-61,000, and 58,000) of cross-reacting immunologic material (CRIM) were observed in control individuals. Decreased amounts of the same CRIM forms were detected in most type 1 Gaucher disease patients, but single CRIM forms of variable molecular weight were observed in several non-Jewish type 1 variants. One or two CRIM forms of variable molecular weight were found in neuronopathic (type 2 and type 3) patients. The amount of CRIM was severely decreased in the majority of the type 2 and type 3 patients; one American black type 2 patient was CRIM negative. With this one exception, one CRIM form was detected in the cell-free culture media from all normal or Gaucher disease fibroblasts that had an Mr approximately 2,000 greater than the highest respective intracellular molecular-weight form. All intra- or extracellular CRIM forms were reduced to a single form after deglycosylation with N-Glycanase. In addition, the radioactivity from [3H]Br-conduritol B epoxide, a specific covalent inhibitor of beta-Glc, localized to the CRIM forms of beta-Glc on immunoblots. These results indicate that all subtypes and variants of Gaucher disease result from mutations that alter the stability and/or processing of beta-Glc. Furthermore, the heterogeneity of the CRIM patterns within and among the variants of Gaucher disease cause the diagnostic usefulness of immunoblotting to be restricted to those families in which the phenotype has been well established.

Human acid beta-glucosidase: Northern blot and S1 nuclease analysis of mRNA from HeLa cells and normal and Gaucher disease fibroblasts

Human acid beta-glucosidase (beta-Glc) mRNA was evaluated by dot blot, Northern blot, and S1 nuclease analyses of extracts of HeLa cells and cultured fibroblasts from normal individuals and Gaucher disease patients. Dot blot quantitation indicated an equal concentration of specific mRNA in all sources. Northern blot analyses demonstrated the presence of three poly (A)+ mRNAs of about 5,600, 2,500, and 2,000 nucleotides in length from all cell extracts. All three mRNAs were present in normal amounts in fibroblast extracts from several subtypes and variants of Gaucher disease. The largest poly (A)+ mRNA species was thought to represent an unspliced nuclear precursor for the two smaller beta-Glc mRNAs. S1 nuclease analyses, using SP6 transcripts of beta-Glc cDNA, indicated that the 2,000 nucleotide mRNA differs from the 2,500 nucleotide form at both the 5' and 3' ends. These results are consistent with the use of an alternate 5' splice site and 3' polyadenylation signal. These results also suggest that the subtype and variants of Gaucher disease result from single base alterations that lead to the synthesis of defective beta-Glc.

Genetic heterogeneity in Gaucher disease

Considerable clinical variability occurs in adult Gaucher disease type I and three main subtypes may be delineated: a very mild form, a severe form, and a moderate form which itself presents various clinical manifestations. A study based on 25 families from our clinic and a review of published reports showed that when both parents were heterozygous and more than one child was affected with Gaucher disease type I, there was always intrafamilial similarity concerning the three subtypes. In families where one parent and at least one child were affected, variability in the clinical subtype of Gaucher disease type I might occur among the affected members of the family. We propose that the three different clinical subtypes of this disease reflect the genetic heterogeneity of two alleles, G1a and G1b and the three corresponding genotypes represent the three different subtypes of the disease.

Glucocerebrosidase "processing" and gene expression in various forms of Gaucher disease

Immunoblots were prepared using extracts of fibroblasts derived from five controls and from four unrelated patients with type I, three with type II, and two with type III Gaucher disease. Five monoclonal antisera and two rabbit sera, crude and affinity purified, were utilized to detect antigen transferred to nitrocellulose paper. Only a band of 63,000 molecular weight (Mr) was consistently detected. We found no 56-K band either in normal or in Gaucher disease fibroblast extracts. Thus, using a variety of antisera, we are unable to verify the claim that the types of Gaucher disease can be differentiated from one another by immunoblotting.

Gene mapping and leader polypeptide sequence of human glucocerebrosidase: implications for Gaucher disease

Analysis of immunologic cross-reacting material in Chinese hamster-human somatic cell hybrids allowed assignment of the structural gene for glucocerebrosidase (glucosylceramidase; beta-D-glucosyl-N-acylsphingosine glucohydrolase, EC 3.2.1.45) to chromosome 1 bands q21-q32. In situ hybridization of a radiolabeled human glucocerebrosidase cDNA to high resolution human chromosomes demonstrated that a single locus encoding glucocerebrosidase is on 1q21, adjacent to a region of chromosome 1 (1qh) abundant in structural heteromorphisms. We also have identified a hydrophobic leader polypeptide encoded by this locus, permitting a more complete description of the biosynthesis of the enzyme. These results suggest that the type-specific protein polymorphisms in Gaucher disease result from mutations at this single locus, whose segregation might be followed by linkage to visible chromosomal heteromorphisms.

Gaucher disease: comparative study of acid phosphatase and glucocerebrosidase in normal and type-1 Gaucher tissues

Acid phosphatase activity was determined in serum, cultured fibroblasts, and peripheral blood lymphocytes of six splenectomized adult patients with non-neuropathic Gaucher disease in two Canadian families. Elevated levels of serum acid phosphatase activity (520-711% of normal) were found in four patients who also developed orthopedic complications associated with Gaucher disease, including intermittent bone pain, arthritis, collapse of femoral head, and pathological fractures. Serum acid phosphatase activity in two patients who do not have bone involvement were found to be within the normal range. Contrary to the serum enzyme, acid phosphatase activity in lymphocytes and cultured fibroblasts of all of the patients was within the normal range. Deficient glucocerebrosidase (7.5-15.5% of normal) and acid beta-glucosidase (13.8-27.8% of normal) activities were noted in all probands. Similarly, normal levels of fibroblast and lymphocyte acid phosphatase activity were found in Gaucher heterozygotes whose glucocerebrosidase activity was about 50% of normal. Acid polyacrylamide gel electrophoresis and acid phosphatase activity staining of the patients' sera showed that the elevated acid phosphatase is isozyme type 5 osteoclastic origin. The apparent Michaelis constant, Km, of fibroblast glucocerebrosidase for the natural substrate was 0.6 +/- 0.1 mM for controls and 0.6 +/- 0.2 mM for the patients. These data suggest that the assay of serum acid phosphatase activity for the presumptive diagnosis of Gaucher disease is not completely reliable and that the elevated level of serum acid phosphatase in Gaucher disease is most likely a secondary phenomenon which may be indicative of bone involvement in some patients with this disorder. It also demonstrates the clinical heterogeneity of type 1 Gaucher disease, even among full sibs of the same heterozygous parents.

Genetic heterogeneity in Gaucher disease: physicokinetic and immunologic studies of the residual enzyme in cultured fibroblasts from non-neuronopathic and neuronopathic patients

To elucidate the genetic heterogeneity in the three major phenotypic subtypes of Gaucher disease, the residual acid beta-glucosidase in fibroblasts from patients with all three subtypes from different ethnic and demographic groups was investigated by comparative kinetic, thermostability, and immunotitration studies. The kinetic studies delineated three distinct groups (designated A, B, and C) of residual activities with characteristic responses to the enzyme modifiers, taurocholate (or phosphatidylserine), and glucosyl sphingosine (or N-hexyl glucosyl sphingosine); Group A residual enzymes responded normally to these modifiers. All neuronopathic patients (types 2 and 3) and most non-Jewish, non-neuronopathic patients (type 1) had group A residual activities and thus could not be distinguished by their kinetic properties. Group B residual enzymes had markedly abnormal responses to these modifiers. All Ashkenazi and only two non-Jewish type 1 patients had group B residual activities. Group C residual activity had an intermediate response to all modifiers and represented a single Afrikaner type 1 patient. Pedigree studies indicated that this patient was a genetic compound for the group A (type 2) and group B (type 1) mutations. Thermostability studies showed additional heterogeneity of the residual activities within the three kinetic groups. Group A (type 2) and group B (type 1) enzymes had similarly decreased thermostabilities. In contrast, group A (type 1) residual activities were heterogeneous; three classes of thermostabilities were found among these enzymes: normal, decreased, and increased. Immunotitration of equal amounts of the normal or Gaucher disease beta-glucosidase activities with monospecific IgG indicated that the enzyme proteins from most Gaucher disease patients were antigenically altered and/or that large amounts of catalytically abnormal or inactive antigen were present. A decreased amount of antigenically and catalytically normal enzyme was present in a group A, type 1 African black patient, suggesting decreased stability or synthesis of his mutant acid beta-glucosidase. These kinetic, immunologic, and thermostability studies indicated that 1) type 1 Gaucher disease is biochemically heterogeneous and results from at least four distinct allelic acid beta-glucosidase mutations that alter enzyme structure and/or function, 2) neuronopathic and non-Jewish non-neuronopathic phenotypes cannot be distinguished reliably by kinetic analyses alone, and 3) the Ashkenazi type 1 Gaucher disease results from a unique mutation that alters a specific active site domain of acid beta-glucosidase.

Glycosphingolipid studies of visceral tissues and brain from type 1 Gaucher disease variants

Glucosylceramide and glucosylsphingosine isolated from spleen, liver and brain were quantitated and characterized in two unrelated patients with Gaucher disease, neither of whom had clinical or neuropathologic evidence of neuronal involvement. Visceral glucosylceramide accumulation did not differ in the two patients. Hepatic glucosylsphingosine content was 2-fold greater in a young severely affected 3-year-old American Black patient compared to that in a 56-year-old Ashkenazi Jewish patient. In contrast, significant differences in glycosphingolipid content and composition were observed in the brains of these two cases. Cerebral and cerebellar cortical glucosylceramide accumulated to a greater extent (3-fold) in the severely affected 3-year-old patient compared to that in the older case. The compositions of the acyl and sphingosyl base residues of glucosylceramide in the cerebral and cerebellar cortices from the Ashkenazi Jewish patient were similar to those in normal individuals. In comparison, the gray matter glucosylceramide in the severely affected patient had increased percentages of stearic acid (18:0) and eicosasphingenine (d20:1), suggesting that the accumulated substrate was derived from the brain ganglioside pool. Glucosylsphingosine was found in large amounts only in cerebral and cerebellar cortices from the severely affected patient. The glycolipid content and composition in this patient was similar to that found in the Norrbottnian (Type 3) form of Gaucher disease. The differences in glucosylceramide acyl and sphingosyl base composition in gray matter from the severely affected patient and that in the Ashkenazi Jewish patient suggested that the accumulated substrates were metabolized differently by the residual enzymes in each case.(ABSTRACT TRUNCATED AT 250 WORDS)

Gaucher disease types 1, 2, and 3: differential mutations of the acid beta-glucosidase active site identified with conduritol B epoxide derivatives and sphingosine

To elucidate the genetic heterogeneity in Gaucher disease, the residual beta-glucosidase in cultured fibroblasts from affected patients with each of the major phenotypes was investigated in vitro and/or in viable cells by inhibitor studies using the covalent catalytic site inhibitors, conduritol B epoxide or its bromo derivative, and the reversible cationic inhibitor, sphingosine. These studies delineated three distinct groups (designated A, B, and C) of residual activities with characteristic responses to these inhibitors. Group A residual enzymes had normal I50 values (i.e., the concentration of inhibitor that results in 50% inhibition) for the inhibitors and normal or nearly normal t1/2 values for conduritol B epoxide. All neuronopathic (types 2 and 3) and most non-Jewish nonneuronopathic (type 1) patients had group A residual activities and, thus, could not be distinguished by these inhibitor studies. Group B residual enzymes had about four- to fivefold increased I50 values for the inhibitors and similarly increased t1/2 values for conduritol B epoxide. All Ashkenazi Jewish type 1 and only two non-Jewish type 1 patients had group B residual activities. The differences in I50 values between groups A and B also were confirmed by determining the uninhibited enzyme activity after culturing the cells in the presence of bromo-conduritol B epoxide. Group C residual activity had intermediate I50 values for the inhibitors and represented a single Afrikaner type 1 patient: this patient was a genetic compound for the group A (type 2) and group B (type 1) mutations. These inhibition studies indicated that: Gaucher disease type 1 is biochemically heterogeneous, neuronopathic and non-Jewish nonneuronopathic phenotypes cannot be reliably distinguished by these inhibitor studies, and the Ashkenazi Jewish form of Gaucher disease type 1 results from a unique mutation in a specific active site domain of acid beta-glucosidase that leads to a defective enzyme with a decreased Vmax.

A method for enrichment of hybrid somatic cells: complementation studies in certain lysosomal enzymopathies

An improved method, which combined a number of published techniques, is described for the polyethylene-glycol-induced fusion of mononuclear human skin fibroblasts in the presence of phytohaemagglutinin-P and for the subsequent isolation of polynuclear cells by Ficoll gradient sedimentation. Enriched cultures contain between 60 and 75% multinucleated cells and may be maintained in culture without fetal calf serum for up to 14 days without significant overgrowth by the few contaminating mononuclear parental cells. Complementation appears not to occur between GM1 gangliosidosis and mucopolysaccharidosis, type VI B (Morquio) cell strains; this experimental observation provides support for the earlier hypothesis that the mutations for these conditions are allelic. Earlier observations that complementation does not occur between selected phenotypic variants (viz., neuronopathic forms and those without neurological involvement) of sphingomyelin storage (Niemann-Pick) disease or Gaucher's disease are confirmed.

New ocular findings in Gaucher's disease: a report of two brothers

White deposits in the peripheral corneal endothelium, chamber angle and pupil margin are new findings in 1 of a sibship of 2 males affected by Gaucher's disease.

Use of activators and inhibitors to define the properties of the active site of normal and Gaucher disease lysosomal beta-glucosidase

Lysosomal beta-glucosidase ('glucocerebrosidase') in peripheral blood lymphocyte and spleen extracts from normal individuals and Ashkenazi-Jewish Gaucher disease type-1 patients were investigated using several modifiers of glucosyl ceramide hydrolysis. The negatively charged lipids, phosphatidylserine and taurocholate, had differential effects on the hydrolytic rates of the normal and Gaucher disease enzymes from either source. With the normal enzyme, either negatively charged lipid (up to 1 mmol/l) increased the reaction rates, while decreasing hydrolytic rates were obtained at greater concentrations. In comparison, the peak activities of the Gaucher enzymes were observed at about 2-3 mmol/l or 5-8 mmol/l of phosphatidylserine or taurocholate, respectively. These negatively charged lipids altered only the velocity of the reactions; the apparent Km values were not affected. Taurocholate or phosphatidylserine also facilitated the interaction of the normal enzyme with conduritol B epoxide, a covalent inhibitor of the catalytic site. Compared to the normal enzyme, the Ashkenazi-Jewish Gaucher type-1 enzyme required about 5-fold greater concentrations of conduritol B epoxide for 50% inhibition. Neutral or cationic acyl-beta-glucosides were found to be competitive or noncompetitive inhibitors of the enzymes, respectively. Alkyl beta-glucosides were competitive (or linear-mixed type) inhibitors of the normal splenic or lymphocyte enzyme with competitive inhibition constants (Ki) inversely related to the chain length. With octyl and dodecyl beta-glucoside nearly normal competitive Ki values were obtained with the splenic enzymes from Gaucher patients. These Ki values were not influenced by increasing phosphatidylserine or taurocholate concentrations. In contrast, the cationic lipids, sphingosyl-1-O-beta-D-glucoside (glucosyl sphingosine) and its N-hexyl derivative, were noncompetitive inhibitors whose apparent Ki values for the normal enzyme were 30 and 0.25 mumol/l, respectively. The Ki values for these sphingosyl glucosides were about increased 5 times for the Gaucher type-1 enzymes from Ashkenazi-Jewish Gaucher disease type-1 patients. The Ki values of glucosyl sphingosine for the normal or mutant enzymes were directly related to increasing concentrations of phosphatidylserine or taurocholate. This latter site appears to be specifically altered by a mutation in the structural gene for lysosomal beta-glucosidase in the Ashkenazi-Jewish form of type-1 Gaucher disease.

Gaucher's disease

This is a review of the classification, pathophysiology, and clinical manifestations of Gaucher's disease. The orthopedic manifestations of the disease include bone pain syndromes, pathologic fractures, and avascular necrosis of the femoral head in children and adults.

Sodium taurocholate effect on beta-glucosidase activity: a new approach for identification of Gaucher disease using the synthetic substrate and leucocytes

In this work we have studied the leucocytes and sera of 3 Gaucher patients, 4 obligate heterozygotes, 11 brothers and sisters of patients and 11 controls. Beta-glucosidase activity with 4-M-U-beta-glucopyranoside has been assayed at different pH's, in the presence of pure sodium taurocholate. At pH 4.5 and 5.0 sodium taurocholate activates the beta-glucosidase of control leucocytes, but inhibits the residual enzyme present in Gaucher leucocytes. The ratio of beta-glucosidase activity in the presence and absence of this effector seems to be a good approach to the diagnosis of Gaucher disease and it has proved indispensible in one patient's diagnosis. The apparent Km of beta-glucosidase determined for the same substrate, at pH 4.5 and 5.5 in the presence of sodium taurocholate showed markedly lower values in the patients than in the controls. An increased serum acid phosphatase activity, previously described as a secondary alteration in Gaucher disease, has also been studied and seems to be a useful complementary test, particularly when its age dependence is taken into account.

An adult form of Gaucher's disease with a huge tumour formation of the right tibia

A case of adult, chronic or non-neuropathic, Gaucher's disease is presented. Severe bony changes, particularly involving the lower limbs developed after a splenectomy had been carried out. Our patient had all the orthopaedic complications of Gaucher's disease. Further, a huge tumour was present in the right tibia caused by the proliferation of Gaucher cells. This feature may be unique but pseudotumour should be listed in the possible orthopaedic complications of Gaucher's disease. The patient was bedridden, but was able to use a wheelchair after his leg was amputated.

Complementation analysis in Gaucher disease using single cell microassay techniques. Evidence for a single "Gaucher gene"

Gaucher disease is a lysosomal storage disorder resulting from a deficiency of acid beta-glucosidase. Several clinical forms have been described, including infantile, juvenile, and adult onset variant. We have examined complementation in infantile and adult forms of Gaucher disease by monitoring enzyme activity in multinucleate cells produced by fusing skin fibroblasts from different patients in the presence of polyethylene glycol. beta-Glucosidase activity was monitored in lysates of individual multinucleate cells by a microassay method utilizing methylumbelliferyl-beta-D-glucoside as the substrate (normal: 1.3 +/- 0.12 x 10(-13) mol/h/cell). The microassay was linear with time up to 4 h, for up to 20 mononucleate cells, and for individual multinucleate cells containing up to 12 nuclei. Complementation was examined in 11 fibroblasts strains fused in all pairwise combinations. In no instance was there any clear indication of complementation (at least 10-15% of normal activity to adequately account for experimental variation) although there was an indication of marginal increases in some fusions. On the other hand, the expected 50% activity was obtained in "heterozygous" fusions (normal/mutant) for both types of clinical variants. Our results are consistent with a single gene, presumably the structural gene encoding the enzyme, responsible for at least the infantile and adult variants, and confirm the autosomal recessive nature of the disorder.

Inherited disorders in the Afrikaner population of southern Africa. Part I. Historical and demographic background, cardiovascular, neurological, metabolic and intestinal conditions

Certain genetic disorders occur with unusually high frequency in the Afrikaner population of southern Africa. Conditions of this type (reviewed in Part I of this article) include familial hypercholesterolaemia, progressive familial heart block, Huntington's chorea, porphyria variegata, Gaucher's disease, cystic fibrosis and familial colonic polyposis. This genetic situation is explicable to some extent on the basis of the demographic development of the Afrikaner population during the 14 generations since the arrival of the first immigrants from Holland more than 330 years ago.

The role of splenectomy in Gaucher's disease

Thirteen patients underwent splenectomy for Gaucher's disease. All patients were Jewish; 12, of Ashkenazi descent, had the chronic (type 1) form, and one child, of Sephardic (Persian) origin, probably had the intermediate (type 3) form. Hypersplenism was the indication for surgery in 11 patients, mechanical problems in the remaining two. The weight of the resected spleens ranged from 1.06 to 13 kg. Following surgery, hypersplenism (thrombocytopenia in particular) was improved, and the mechanical disturbances were relieved in all patients. There were no deaths and no morbidity related to the operative procedure. Long-term follow-up demonstrated progressive hepatomegaly without evidence of hepatic dysfunction in any of the patients. Bone marrow involvement manifested by osteoarticular complications appeared in five patients. Splenectomy is, we believe, a safe mode of treatment for type 1 Gaucher's disease.

Determination of Gaucher's disease phenotypes with monoclonal antibody

Discrimination between the three clinical subtypes of Gaucher's disease based on the molecular forms of beta-glucocerebrosidase detected by monoclonal antibody is described. In normal fibroblast extracts, cross-reacting material (CRM) to human placental glucocerebrosidase is detected at Mr approximately equal to 63 000, 61 000 and 56 000. In Type 1 Gaucher's disease, the major fibroblast CRM has a Mr approximately equal to 56 000,, with less CRM seen at 61 000 and 56 000. Type 3 fibroblast extracts have a single CRM form at Mr approximately equal to 63 000. No CRM is found in Type 2 Gaucher's disease fibroblasts with monoclonal antiglucocerebrosidase antibody 8E4.

Immunological and catalytic quantitation of splenic glucocerebrosidase from the three clinical forms of Gaucher disease

The enzymatic activity of glucocerebrosidase in splenic extracts of the adult nonneurological form of Gaucher disease (type I) was 15% +/- 7% of normal, and the titer of enzyme cross-reacting material (ECRM) in these spleens was 54% +/- 9% of normal. The titer of ECRM in splenic extracts of tissues obtained from patients with the neurological forms of Gaucher disease (types II and III) was essentially the same as in type I Gaucher spleens (59% +/- 10% of normal), but the measurable catalytic activity of glucocerebrosidase in these spleens was substantially lower than that found in type I Gaucher spleens (2.3% +/- 0.6% of normal). Thus, the attentuated glucocerebrosidase activity in spleens from all three forms of Gaucher disease appears to stem from a structurally mutated enzyme that is altered in its catalytic efficiency and possibly in its antigenic expression.

Mutations of glucocerebrosidase: discrimination of neurologic and non-neurologic phenotypes of Gaucher disease

Multiple molecular forms of beta-glucocerebrosidase that permit discrimination between neurologic and non-neurologic phenotypes of Gaucher disease have been identified radioimmunologically in fibroblasts and human brain tissue. In normal human fibroblasts these forms have been shown by NaDodSO4/polyacrylamide gel electrophoresis to have apparent Mr of 63,000 (form A1), 61,000 (form A2), and 56,000 (form B). The Mr 63,000 form may be a precursor of the Mr 56,000 form. Non-neurologic Gaucher disease (type 1) fibroblasts and normal brain tissue are characteristic in that they contain only one major immunoreactive protein, the Mr 56,000 form. In contrast, fibroblast extracts and brain tissue from neurologic Gaucher disease phenotypes contain only the higher molecular weight forms A1 and A2. These data and the low residual activity of the enzyme in all the variants of Gaucher disease suggest that the mutations of beta-glucocerebrosidase are allelic and involve the active site.

Coexistence of Gaucher Disease and Philadelphia positive chronic granulocytic leukemia

A patient with coexistent Gaucher disease and Philadelphia positive chronic granulocytic leukemia (CGL), who subsequently developed myeloblastic leukemia, is described. The diagnosis of CGL was established according to standard clinical, morphological, biochemical, and cytogenetic data, while the diagnosis of true Gaucher disease was based on biochemical data and the presence of Gaucher cells with typical ultrastructural features in the bone marrow and spleen. Enzyme studies showed low activity of ceramide-beta-glucosidase in the patient's peripheral blood leukocytes, skin fibroblasts, and splenic tissue and the presence of increased amounts of ceramide-beta-glucoside in the spleen. This case is reported in order to draw attention to the possible coexistence of these two diseases in the same patient, as opposed to the well-recognized finding of "Gaucher-like" cells in the bone marrow of patients with CGL. Enzyme studies enable distinction between these two situations.

beta-Glucosidase assays in the diagnosis of Gaucher's disease

The description in 1965 of glucocerebroside: beta-glucosidase as the enzymic defect in Gaucher's disease stimulated considerable research interest and effort toward establishing rapid, reliable, and inexpensive enzymic assays for diagnostic purposes and carrier detection. Here, we consider some of the methods currently in use in which the substrate is the synthetic glucoside, 4-methylumbelliferyl-beta-D-glucopyranoside, and leukocytes and fibroblasts are the sources of enzyme. We also consider the concepts of the "acid beta-glucosidase" and multiple forms of beta-glucosidase that have been proposed to explain the effectiveness of the fluorometric assays. Finally, we analyze the limitations of each method and discuss the difficulties involved in instituting heterozygote screening programs in the general population.