Molecular analysis of Gaucher disease: screening of patients in the Montreal/Quebec region.

Gaucher disease, the most prevalent lysosomal storage disease, is an autosomal recessive sphingolipidosis resulting from deficient glucocerebrosidase activity. Genomic DNA of the structural gene of glucocerebrosidase from normal individuals and fifteen unrelated patients with the three clinical forms of Gaucher disease from the Montreal/Quebec region were amplified by the polymerase chain reaction technique. Allele-specific oligonucleotide dot blot hybridization and restriction fragment length polymorphism were used to screen for five of the mutations [mutations 120, 370, 415, 444 (Nci), and 463] in exons 5, 9, and 10 of glucocerebrosidase gene. It was noted that all of the patients had at least one of the known mutant alleles. However, 9 patients (9/15 = 60%) had an unknown allele. Mutation 370 in exon 9 was present in the heteroallelic form in eight out of the nine patients with type 1 Gaucher disease, but was present in none of the six patients with type 2 or type 3 Gaucher disease. The Nci mutation in exon 10 was present in the heteroallelic form in three patients with type 1 Gaucher disease and in either the heteroallelic or homoallelic form in all of the six patients with type 2 or type 3 Gaucher disease. The 415/Nci mutations were found in a mildly affected 29-year-old patient with type 1 Gaucher disease, as well as in an infant with the type 2 form. These findings demonstrate the clinical and molecular genetic heterogeneities of Gaucher disease, the presence of unknown Gaucher allele(s) in most (60%) of the patients surveyed, and the occasional inexplicable lack of phenotype-genotype correlation among some patients.(ABSTRACT TRUNCATED AT 250 WORDS)     

DNA mutational analysis of type 1 and type 3 gaucher patients: How well do mutations predict phenotype?

The wide spectrum of clinical manifestations resulting from glucocerebrosidase deficiency complicates genetic counseling for Gaucher disease. The identification of mutations in the glucocerebrosidase gene has enabled studies of genotype–phenotype correlation. However, a genotypic analysis of 60 type 1 and type 3 Gaucher patients reveals that the 5 most common Gaucher mutations, N370S, L444P, R463C, 84insG, and IVS2 + 1 G→A, can be found both in patients with and without neurologic manifestations. Moreover, although some generalizations can be made about mutations that are more frequently encountered in particular patient populations, Gaucher patients sharing identical genotypes can exhibit considerable clinical heterogeneity. Thus in considering rationale for population screening one cannot rely solely on PCR determined DNA mutation analysis to reliably predict prognosis in Gaucher disease. © 1994 WiIey-Liss, Inc. © 1994 Wiley-Liss, Inc.     

The E326K mutation and Gaucher disease: mutation or polymorphism?

Gaucher disease is caused by mutations in the gene for human glucocerebrosidase, a lysosomal enzyme involved in the intracellular hydrolysis of glucosylceramide. While over 150 different glucocerebrosidase mutations have been identified in patients with Gaucher disease, not all reported mutations have been fully characterized as being causative. One such mutation is the E326K mutation, which results from a G to A nucleotide substitution at genomic position 6195 and has been identified in patients with type 1, type 2 and type 3 Gaucher disease. However, in each instance, the E326K mutation was found on the same allele with another glucocerebrosidase mutation. Utilizing polymerase chain reaction (PCR) screening and restriction digestions of both patients with Gaucher disease and normal controls, we identified the E326K allele in both groups. Of the 310 alleles screened from patients with Gaucher disease, the E326K mutation was detected in four alleles (1.3%). In addition, screening for the E326K mutation among normal controls from a random population revealed that three alleles among 316 screened (0.9%) also carried the E326K mutation. In the normal controls with the E326K allele, the glucocerebrosidase gene was completely sequenced, but no additional mutations were found. Because the E326K mutation may be a polymorphism, we caution that a careful examination of any allele with this mutation should be performed to check for the presence of other glucocerebrosidase mutations.     

The clinical, molecular, and pathological characterisation of a family with two cases of lethal perinatal type 2 Gaucher disease.

It has recently been emphasised that a subset of patients with type 2 Gaucher disease die in the neonatal period. This report describes an Afghani family with two conceptuses having severe, prenatally detected Gaucher disease. Mutational analysis showed that the family carried a known complex allele which included mutations at amino acids L444P, A456P, and V460V. Although glucocerebrosidase RNA was present, an affected fetus had virtually no glucocerebrosidase cross reactive material on western analyses. The severe clinical course and pathology observed in these patients resemble that of the null allele Gaucher mouse, and suggest that the absence of glucocerebrosidase activity results in early death.     

Identification of a 55-bp deletion in the glucocerebrosidase gene in Gaucher disease: phenotypic presentation and implications for mutation detection assays

A 55-bp deletion in exon 9 of the glucocerebrosidase gene was identified in a 28-year-old male affected with Gaucher disease. The diagnosis was established during an evaluation for mild pancytopenia and was confirmed by bone marrow histology and biochemical studies. The patient is of German ancestry. Initial DNA testing indicated homozygosity for the N370S mutation. However, subsequent testing of the patient's parents suggested that the patient and his mother carried a null allele by our assay for N370S. Further molecular studies identified a 55-bp deletion in exon 9 of the glucocerebrosidase gene (g.6767_6822del55). This deletion has been previously reported in a patient with severe Gaucher disease (1), and is present in the glucocerebrosidase pseudogene. In the previously reported case, initial DNA testing also suggested the genotype N370S/N370S, but further mutation studies were undertaken because clinical severity was greater than expected for that genotype. In contrast, our patient has an unusually mild clinical course. Thus, clinical severity cannot be reliably used to determine when to test for the presence of the 55-bp deletion. While the 55-bp deletion is not reported to be common, its actual frequency may be underestimated since it eludes detection by many standard clinical assays for Gaucher disease. This report points out the need to consider this deletion mutation which may cause erroneous interpretation of results in existing assays for the common mutations N370S and L444P. Furthermore, the importance of recommending parental analysis for individuals who test homozygous for autosomal mutations is highlighted.     

Gaucher disease in Romanian patients: incidence of the most common mutations and phenotypic manifestations

Gaucher disease (GD) is an inherited glycolipid storage disorder resulting from the deficiency of glucocerebrosidase. It is the most frequent lysosomal storage disease in Romania, accounting for 70% of all lysosomal disorders diagnosed since 1997 in this country. The prevalence of six common mutations (N370S, L444P, R463C, 84GG, recNciI and recTL) and their phenotypic impact were studied in 20 type 1 GD patients of non-Jewish origin. Mutation analysis identified 77.8% of the GD alleles. The N370S mutation had the highest prevalence (50%), followed by the L444P (22.2%) and the recNciI (5.6%) alleles. Mutations R463C, 84GG and recTL have not been found in our patients. Rare or novel mutations likely accounted for 22.2% of the disease-producing uncharacterised alleles. Our study indicates a high prevalence of type 1 among Romanian GD patients. Clinical phenotype and disease severity were evaluated according to the standardised severity score index. Genotype-phenotype correlations were similar to those reported for other Caucasian non-Jewish populations. The absence of neuronopathic disease in patients presenting at least one copy of the N370S allele was confirmed, but the relative mildness of N370S homozygotes was not a constant feature among our patients. The presence of the L444P or of uncharacterised sporadic mutations was always associated with severe clinical manifestations, even in compound heterozygotes with the N370S allele. A large degree of phenotypic variability was observed in patients displaying the same genotype. The particularities of genotype-phenotype correlations may suggest the impact of other genetic or non-genetic factors on the clinical picture.     

A novel mutation (V191G) in a German-British type 1 Gaucher disease patient. Mutations in brief no. 131. Online

Gaucher disease results from mutations in the glucocerebrosidase gene located on human chromosome 1q21. Three clinical forms of Gaucher disease have been described: type 1, nonneuropathic; type 2, acute neuropathic; and type 3, subacute neuropathic. We have identified a novel mutation in a German-British patient with type 1 Gaucher disease which results in V191G of the glucocerebrosidase polypeptide. Because the mutation abolishes a HphI cleavage site, its presence was confirmed by HphI RFLP analysis of PCR-amplified genomic DNA. In the second allele of the patient, the mutation identified was g.5841A G(N370S). Sequence analysis of the remainder of the coding region of the gene as well as the exon-intron boundaries showed identity to normal controls. Because mutation N370S has so far been found only in type 1 Gaucher disease and postulated to result in mild clinical presentation, and since the clinical course of this patient has been relatively mild with minimal skeletal involvement, we speculate that the V191G/N370S genotype may also result in good prognosis.     

Expression of mutated glucocerebrosidase alleles in human cells

Gaucher disease is a heterogeneous disease characterized by impaired activity of the lysosomal enzyme glucocerebrosidase. This heterogeneity is attributed to a large number of mutations in the corresponding gene. In order to test the biochemical properties of some mutations prevalent among Israeli populations, the normal human glucocerebrosidase cDNA and cDNAs carrying mutations N370S, L444P, D409H, recTL, recNcil, P415R and 84GG were coupled to the T7 RNA polymerase promoter in a vaccinia virus- derived expression vector (pTM-1). Recombinant viruses were produced and used to infect human tissue culture cells. RNA and protein stability, recognition by anti-glucocerebrosidase monoclonal antibodies and intracellular enzymatic activity were measured. The results demonstrated that the D409H allele directed synthesis of cytoplasmic RNA with decreased stability compared with its normal counterpart or other mutated forms. The D409H and L444P mutated proteins had lower stability than that of their normal counterpart, while the recNcil- mutated protein was more stable. Only glucocerebrosidase forms harboring leucine at position 444 were recognized by the anti- glucocerebrosidase monoclonal antibodies used (8E4 and 2C7). Measurements of enzymatic activity of the recombinant proteins in cells loaded with a fluorescent glucosylceramide demonstrated that the N370S mutated enzyme had activity similar to that of the normal enzyme. The other mutated enzymes exhibited varying degrees of activities, generally corresponding to the phenotypes with which they are associated. The results presented demonstrate the use of the vaccinia virus-derived expression system and of loading living cells with fluorescent substrate as efficient tools for studying mutants in Gaucher disease and in other lysosomal diseases.      

Molecular screening of Japanese patients with gaucher disease: Phenotypic variability in the same genotypes

Gaucher disease is the most prevalent sphingolipidosis, characterized by genetic deficiency of lysosomal hydrolase glucocerebrosidase, and is inherited in an autosomal recessive manner. To characterize the molecular basis of Gaucher disease in Japan, we analyzed for the presence of the two known mutations (1448C and 754A) in the glucocerebrosidase gene of 15 patients (14 families) with Gaucher disease by selective amplification and restriction endonuclease analysis. We found that the 1448C and 754A mutations occurred in all three clinical subtypes of Japanese Gaucher disease patients. The 1448C mutation was found on 12 (40%) out of 30 chromosomes (44% allele frequency in nonneuronopathic form, and 33% in neuronopathic forms), while homozygosity for this mutation was only found in two nonneuronopathic patients (age of 1 year 6 months and 7 years). We detected the 754A mutation on 6 (20%) out of 30 chromosomes. No patient was homozygous for 754A mutation. Furthermore, we identified four patients who were compound hetrozygote for 754A and 1448C. One of these was a type 3 Gaucher patient, but the other three patients were free from central nervous system manifestations at the time of observation. These results indicate that phenotypic presentation of Gaucher disease including the presence of nervous manifestation, progression, and severity of disease, may be affected by other genetic, environmental, or developmental factors, as well as the glucocerebrosidase genotype. © 1993 Wiley-Liss, Inc.     

Glucocerebrosidase genotype of Gaucher patients in The Netherlands: Limitations in prognostic value

Gaucher disease is a recessively inherited lysosomal storage disorder that is caused by a deficiency in glucocerebrosidase activity. The clinical expression is markedly heterogeneous with respect to age of onset, progression, severity, and neurological involvement. The relative incidence of glucocerebrosidase (GC) mutations has been studied extensively for Jewish but not for non-Jewish Caucasian patient populations. The present survey on mutant GC genotypes prevalent in Gaucher disease in The Netherlands was taken of 72 patients from different genetic backgrounds. This number is more than half the total number of affected Gaucher patients to be expected on the basis of the incidence of the disorder in this country. Analysis of nine GC mutations led to the identification of 74% of the mutant GC alleles in patients from 44 unrelated Dutch families (i.e., families that have lived in The Netherlands for at least several generations) and of 44% of the mutant GC alleles in patients from nine unrelated families that recently immigrated from both European and non-European countries. The N370S (cDNA 1226G) GC mutation proved to occur most frequently (41%) in the unrelated Dutch patients and less frequently (6%) in the unrelated immigrant patients and was always associated with the nonneuronopathic (Type 1) form of the disease. Apart from the association of the N370S mutation with Type 1 Gaucher disease, the prognostic value of GC genotyping was limited, since a particular GC genotype did not correlate closely to a specific clinical course, or to a specific relative responsiveness to enzyme-supplementation therapy. Hum Mutat 10:348–358, 1997. © 1997 Wiley-Liss, Inc.     

Glucocerebrosidase gene mutations in patients with type 2 Gaucher disease

Gaucher disease, the most common lysosomal storage disorder, results from the inherited deficiency of the enzyme glucocerebrosidase. Three clinical types are recognized: type 1, non-neuronopathic; type 2, acute neuronopathic; and type 3, subacute neuronopathic. Type 2 Gaucher disease, the rarest type, is progressive and fatal. We have performed molecular analyses of a cohort of 31 patients with type 2 Gaucher disease. The cases studied included fetuses presenting prenatally with hydrops fetalis, infants with the collodion baby phenotype, and infants diagnosed after several months of life. All 62 mutant glucocerebrosidase (GBA) alleles were identified. Thirty-three different mutant alleles were found, including point mutations, splice junction mutations, deletions, fusion alleles and recombinant alleles. Eleven novel mutations were identified in these patients: R131L, H255Q, R285H, S196P, H311R, c.330delA, V398F, F259L, c.533delC, Y304C and A190E. Mutation L444P was found on 25 patient alleles. Southern blots and direct sequencing demonstrated that mutation L444P occurred alone on 9 alleles, with E326K on one allele and as part of a recombinant allele on 15 alleles. There were no homozygotes for point mutation L444P. The recombinant alleles that included L444P resulted from either reciprocal recombination or gene conversion with the nearby glucocerebrosidase pseudogene, and seven different sites of recombination were identified. Homozygosity for a recombinant allele was associated with early lethality. We have also summarized the literature describing mutations associated with type 2 disease, and list 50 different mutations. This report constitutes the most comprehensive molecular study to date of type 2 Gaucher disease, and it demonstrates that there is significant phenotypic and genotypic heterogeneity among patients with type 2 Gaucher disease. Hum Mutat 15:181-188, 2000. Published 2000 Wiley-Liss, Inc.     

Prevalence of glucocerebrosidase mutations in the Israeli Ashkenazi Jewish population

Gaucher disease is the most prevalent inherited disease among Ashkenazi Jews. It is very heterogeneous due to a large number of mutations within the glucocerebrosidase gene, whose impaired activity is the cause for this disease. Aiming at determining Gaucher carrier frequency among the Ashkenazi Jewish population in Israel, 1,208 individuals were molecularly diagnosed for six mutations known to occur among Ashkenazi Jewish Gaucher patients, using the newly developed Pronto™ Gaucher kit. The following mutations were tested: N370S, 84GG, IVS2+1, D409H, L444P, and V394L. Molecular testing of these mutations also allows identification of the recTL allele. The results indicated that Gaucher carrier frequency is 1:17 within the tested population. The prevalence of N370S carriers is 1:17.5. This implies that ˜1:1225 Ashkenazi Jews will be homozygous for the N370S mutation. Actually, in our study of 1,208 individuals one was found to be homozygous for the N370S mutation. The actual number of known Ashkenazi Jewish Gaucher patients with this genotype is much lower than that expected according to the frequency of the N370S mutation, suggesting a low penetrance of this mutation. Results of loading experiments in cells homozygous for the N370S mutation, as well as cells homozygous for the L444P and the D409H mutations, exemplified this phenomenon. Hum Mutat 12:240–244, 1998. © 1998 Wiley-Liss, Inc.     

Identification of two novel and four uncommon missense mutations among Chinese Gaucher disease patients

Gaucher disease is the most prevalent lysosomal storage disease. It is panethnic and results from an inherited deficiency of glucocerebrosidase. Most mutations to date have been identified among Jewish and non-Jewish Caucasian patients; mutations in Chinese patients are largely unknown. We have performed nucleotide sequence analysis of PCR-amplified glucocerebrosidase genomic DNA from five unrelated Chinese patients affected with type 1 (non-neuropathic) Gaucher disease. A novel heterozygous C → T mutation at cDNA nucleotide position 475 (R120W) was detected in a patient who is also heterozygous for a C → T transition at cDNA nucleotide position 259 (R48W). In a second patient, a novel, heterozygous T → G transversion at cDNA 226 (F37V) was detected. Mutation 1448 (L444P), the most prevalent mutation among non-Jewish Caucasian Gaucher patients, was found in the heterozygous form in four patients. The mutations in the second Gaucher allele in the other three patients are mutations 254 (G46E), 680 (N188S), and 754 (F213I), which were recently reported in Korean, Arab, and Chinese (Taiwanese) patients. We have developed screening methods that utilize PCR amplification of glucocerebrosidase genomic DNA and Eco571, Nci1, Hinc11, BsaJ1, and Bsr1 restriction endonuclease analyses for the detection of each of these mutations. The population genetics of some of these Gaucher alleles and their implications in genotype/phenotype correlation are discussed. Am. J. Med. Genet. 71:172–178, 1997. © 1997 Wiley-Liss, Inc.     

Is the perinatal lethal form of Gaucher disease more common than classic type 2 Gaucher disease?

In recent years there has been increased recognition of a severe perinatal lethal form of Gaucher disease, the inherited deficiency of lysosomal glucocerebrosidase. We previously reported a case of severe type 2 Gaucher disease which was seen in a medical center in Rotterdam and now present three new cases from two other families seen at the same center. Mutational analyses of these cases revealed two novel mutations, H311R and V398F, located in exons 8 and 9, respectively. The identification of four cases of lethal type 2 Gaucher disease in a single center seems to be a function of increased awareness of this phenotype, rather than of geographic clustering. The actual incidence of lethal type 2 Gaucher disease may be underestimated, as many cases may have been misclassified as collodion babies or hydrops of unknown cause.     

Molecular analysis of Gaucher disease in a Vietnamese-Czechoslovak patient with high residual glucocerebrosidase activity

A Vietnamese-Czechoslovak type 1 Gaucher disease patient with mild hematological complications was found to have approximately 20% of the normal level of fibroblast glucocerebrosidase activity. Using primers that recognize exon 9 sequences of the glucocerebrosidase structural gene absent in the pseudogene, genomic DNA sequences flanking exons 9 and 10 of the glucocerebrosidase structural gene were amplified by the polymerase chain reaction. Allele-specific oligonucleotide hybridization to amplified genomic DNA sequence of exons 9 and 10 showed an A----G transition in exon 9 that resulted in the 370Ser----370Asp substitution in one of the alleles. In the other allele, a T----C transition in exon 10 resulted in the 444Leu----444Pro substitution, creating a NciI cleavage site. The heterozygote status of the patient's parents was confirmed biochemically by the detection of intermediate levels (42-55% of normal) of fibroblast glucocerebrosidase activity. Allele-specific oligonucleotide hybridization to amplified parental genomic DNA showed that the exon 9 mutation was present in the Czechoslovak father, whereas the exon 10 mutation was inherited from the patient's Vietnamese mother. This is the first report of the exon 10 mutation in a person of Vietnamese origin.     

Type 2 Gaucher Disease with Hydrops Fetalis in an Ashkenazi Jewish Family Resulting from a Novel Recombinant Allele and a Rare Splice Junction Mutation in the Glucocerebrosidase Locus

Gaucher disease, the deficiency of the lysosomal enzyme glucocerebrosidase (EC 3.2.1.45), is frequently encountered in the Ashkenazi Jewish population. Carrier screening for Gaucher disease by enzyme analysis performed during a routine pregnancy indicated that both Ashkenazi parents were carriers. Screening for four common Gaucher mutations was subsequently performed on fetal and parental DNA. None of the common Ashkenazi mutations were identified. However, when exons 9–11 were amplified and digested withNciI to detect the L444P mutation, it appeared that the mother and the fetus had an unusual allele and that the expected paternal allele was not present. When the fetal amniocytes were found to have less than 2% of the normal glucocerebrosidase activity and a fetal sonogram revealed hydrops fetalis, the pregnancy was terminated. The diagnosis of severe type 2 Gaucher disease was confirmed at autopsy. Ultrastructural studies of epidermis from the fetus revealed the characteristic disruption of lamellar bilayers, diagnostic for type 2 Gaucher disease. In subsequent studies of the fetal DNA, long-template polymerase chain reaction amplification revealed one appropriately sized band (6.5 kb) and one smaller (5.2 kb) band. Sequencing of the 5.2-kb fragment identified a novel fusion allele resulting from recombination between the glucocerebrosidase gene and its pseudogene beginning in intron 3. This fusion allele was inherited from the father. The result was confirmed by Southern blot analysis using the enzymeSstII. Sequencing of the 6.5-kb fragment identified a previously described, although rare, T-to-G splice junction mutation in intron 10 of the maternal allele, which introduced anNciI site. The couple had a subsequent pregnancy which was also found to be affected. This case study identifies a novel recombinant allele and an unusual splice junction mutation, and demonstrates that even in the Ashkenazi population, screening for common mutations may not accurately identify the most severe forms of the disease.     

A rare G6490 → substitution at the last nucleotide of exon 10 of the glucocerebrosidase gene in two unrelated Italian Gaucher patients

Mutation screening of the glucocerebrosidase gene by SSCP analysis revealed an abnormal pattern of exon 10 in two unrelated Italian Gaucher patients. Direct sequencing of the mutated samples identified a G6490→ A transition. The same mutation has been described before in a Japanese patient with Gaucher disease type III. The clinical phenotype of our patients was type I in one whose second allele carried the N370S mutation and type II in the other one with a L444P mutation. In this latter the G6490→ A substitution cancels a normal Msp I site, while on the opposite chromosome the T6433→ C mutation (L444P) introduces a new Msp I site. Thus, digestion with Msp I of the amplified exon 10 is a useful method for identifying the two mutations simultaneously.     

55-Base pair deletion in certain patients with Gaucher disease complicates screening for common Gaucher alleles

Mutations in the glucocerebrosidase gene which result in Gaucher disease can originate from the highly homologous glucocerebrosidase pseudogene. A 55-bp deletion in exon 9, which corresponds to a 55-bp segment absent from the pseudogene, has been identified in patients with Gaucher disease. We have developed a simple polymerase chain reaction (PCR)-based method to detect this 55-bp deletion, and have found this mutation in 3 of 75 DNA samples (4%) collected from patients with Gaucher disease. Commonly used PCR-based screening methods for specific Gaucher mutations frequently make use of primers either within or surrounding the 55-bp gap to selectively distinguish the glucocerebrosidase gene from the pseudogene. However, if the 55-bp deletion in exon 9 occurs, primers will either fail to produce an amplification product or will produce a shortened product which will be falsely attributed to the pseudogene. This could lead to inaccurate genotyping and genetic counseling for some Gaucher patients and their families. We therefore recommend that laboratories using PCR-based screening techniques involving primers in this region initially determine whether this 55-bp sequence is present. © 1996 Wiley-Liss, Inc.