Hematologically important mutations: Gaucher disease.
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Gaucher Disease↗
Biomedical subjects
T Gelbart
Publications and source records attributed to T Gelbart.
HLA-H mutations in the Ashkenazi Jewish population.
Hereditary hemochromatosis is a common disorder in people of European origin. The HLA-H gene has been found to have two mutations that apparently cause hemochromatosis. The principal mutation, 845G-->A (C282Y), is believed to have arisen relatively recently in the Celtic population. To determine the incidence of this mutation and the other hemochromatosis-associated mutation, 187C-->G (H63D), among Ashkenazi Jews, a people who are believed to have arrived in Europe in about the 8th Century A.D., we have examined the DNA from 381 unrelated Jewish subjects and 206 non-Jewish white controls. The gene frequency for the 845G-->A mutation among Jewish subjects was only 0.013 compared with a frequency of 0.070 among controls, a difference that is significant at the 0.00001 level. The phenotypically milder nt 187C-->G mutation had a frequency of 0.155 in the non-Jewish population and 0.097 in the Jewish population, a difference that was also statistically significant at the <0.01 level.
Genotype↗
HLA-H and associated proteins in patients with hemochromatosis.
BACKGROUND: The 845A(C282Y) mutation in the HLA-H gene accounts for most cases of hereditary hemochromatosis in patients who are of European origin. Some lack this mutation, however, and it is not present in Asian patients. Thus, other mutations either in HLA-H or associated proteins may be present in such patients. HLA-H associates with beta-2-microglobulin. Calreticulin associates with class 1 HLA proteins and appears to be identical with mobilferrin, a putative iron transport protein. These two proteins are therefore candidates for mutations in patients with hemochromatosis. MATERIALS AND METHODS: We have sequenced the coding region and parts of introns of the HLA-H gene, the beta-2-microglobulin gene, and the calreticulin (mobilferrin) gene of 10, 7, and 5 hemochromatosis patients, respectively, selecting those who were not homozygous for the 845A(C282Y) mutation. The number of chromosomes at risk studied were 18 for HLA-H, 14 for beta-2-microglobulin and 10 for calreticulin. RESULTS: We detected 3 new intronic polymorphisms in the HLA-H gene, each a point mutation. Some differences from published sequences of beta-2-microglobulin and calreticulin were documented, but these were uniformly present in all samples. CONCLUSIONS: The lack of additional mutations in the HLA-H gene is remarkable, and we speculate that the C282Y mutation may be a gain-of-function change.
Asia↗
Glucocerebrosidase (Gaucher disease).
Gaucher disease is the most common glycolipid storage disorder, characterized by storage of the glycolipid, glucocerebroside in the liver, spleen, and marrow. The most prevalent form of Gaucher disease is designated type I (MIM 230800). Patients with type I disease may have hepatomegaly, splenomegaly, bone lesions, and less commonly, lung disease, but are free of neurological involvement. Types II (MIM 230900) and III (MIM 2310000), the acute infantile and juvenile forms, respectively, of Gaucher disease, are characterized by the fact that the central nervous system is affected.
Alternative Splicing↗
Mutation analysis in hereditary hemochromatosis.
The DNA of 147 patients of European origin clinically diagnosed with idiopathic hemochromatosis and 193 controls was examined for mutations of the HLA-H gene at nt 845 and nt 187. One hundred twenty-one (82.3%) of the hemochromatosis patients were homozygous and 10 (6.8%) heterozygous for the 845A (C282Y) mutation. All of the homozygous patients were also homozygous for nt 187C, and all 845A heterozygotes had at least one copy of 187C. Thus, the nt 845 and nt 187 mutations were in complete linkage disequilibrium; nt 187 was a C on all chromosomes with the 845A mutation. Eight of the 10 heterozygotes for 845A were heterozygous for 187G(H63D). The excess of heterozygotes at both nt 187 and nt 845 suggested either the presence of as yet undiscovered mutations existing in trans with 845A and in linkage disequilibrium with 187G, or that the 187G itself is a deleterious mutation, which in concert with the 845A can give rise to hemochromatosis. None of the 193 normal controls were homozygous for 845A and 29/193 (15%) were heterozygous for 845A. Although 47/193 (24.3%) of normal controls were heterozygous for the 187G mutation only two of these carried the 845A mutation. If the 187G mutation complemented the 845A mutation with high penetrance in causing hemochromatosis, then the population frequency of the two genes would require that a high proportion of patients with hemochromatosis be heterozygous for 845A and 187G. Instead, the frequency of homozygotes for the 845A mutation was much higher than that of the 845A/187G genotype. Based on our data, the penetrance of the 845A/187G genotype is only 1.5% and based on the data of Feder et al. only 0.5%. In contrast, the penetrance of the homozygous 845A/845A genotype seems to be very high. Thus, screening for this genotype should be very useful.
Alleles↗
Gaucher disease: four families with previously undescribed mutations.
We describe four families with patients with type I Gaucher disease exhibiting previously undescribed mutations of the glucocerebrosidase gene. We found Cherokee Indian woman to have a G-->C substitution in cDNA nucleotide 354, predicting a lysine-->aspargine substitution in amino acid 79 of the processed protein. In a Greek family, we found an allele with a C-->T substitution in nucleotide 475 giving rise to an arginine-->tryptophan substitution at amino acid 120. In another non-Jewish European patient, we identified a C-->T substitution in nucleotide 1223, predicting a threonine-->methionine mutation in amino acid 369. We found two non-Jewish European children to have a C-->T mutation at nucleotide 1357, predicting termination at codon 414. Although siblings carry the same two glucocerebrosidase mutations, in these families as in others we noted considerable differences in severity of clinical manifestations. Finding the reason for these differences is an important goal in the study of Gaucher disease.
Adult↗
Five new Gaucher disease mutations.
DNA from 17 individuals with 20 unidentified alleles was subjected to single-stranded conformation polymorphism analysis and/or sequencing and 5 previously undescribed mutations have been identified: 245T, 259T, 635G, 914C del, and IVS10(+2). Two of these mutations, 914C del and IVS10(+2), are null, or "lethal" mutations. Because the other mutation each of these two patients carried was "mild", the phenotype was type I disease. In addition to the new mutations we describe, the second example of the rare 1448G mutation has been documented in one of the patients. This mutation is particularly interesting because in samples studied by restriction analysis with NciI it can readily be confused with the common 1448C mutation. Reexamination of 28 patients who had previously been diagnosed as carrying the 1448C mutation were confirmed to be 1448C.
Adult↗
The clinical course of treated and untreated Gaucher disease. A study of 45 patients.
One hundred nineteen patients with Gaucher disease were examined in the past 13 years. Of these 45 were examined 3 or more times over a time-span exceeding one year and all such patients are included in this study. Adult patients showed little progression of disease. There were few alterations in the blood counts, no increase in size of liver and spleen, and changes in skeletal lesions were largely confined to pre-existing lesions. Some children appeared to have more progressive disease, but since many of the children in this study were treated with alglucerase, it is difficult to draw conclusions about the natural progression of the disease at earlier ages. Treatment with alglucerase resulted in gradual normalization of blood counts, decrease in the size of liver and spleen, and parallel decreases in the serum angiotensin converting enzyme and chitotriosidase levels. Skeletal symptoms were decreased in all patients, and skeletal lesions showed modest improvement in patients treated for two years or more. The response of patients to low dose/high frequency (2.3 U/Kg 3 x weekly; 30 U/Kg/Mo) therapy was indistinguishable from the response observed and previously reported by others with much larger doses. Changing the dosage from 30 U/Kg/Mo to 120 U/Kg/Mo was not attended by any significant changes in response. Criteria for the selection of patients for treatment with alglucerase are proposed. We suggest that a starting dose of 15 to 30 U/Kg/month, fractionated 3 times weekly be used for all patients, regardless of severity or site of involvement, and that upward dosage adjustments be made only in such rare patients who may not respond adequately to this dose in 6 to 12 months.
Adolescent↗
A strategy for cloning the hereditary hemochromatosis gene.
Selective hybridization of small intestine and liver cDNA libraries was carried out using yeast artificial chromosomes (YACs) surrounding D6S105, the microsatellite that appears to be close to the gene for hereditary hemochromatosis (HFE). Of 14 candidate probes hybridizing with these YACs, only one, designated. LD5-1, detected abnormalities in southern blots of patients with hemochromatosis. Two different abnormalities. were detected in 3 of 55 patients with hemochromatosis with the LD5-1 probe, and one of these was detected in one of 44 normal subjects. The gene that hybridizes with this probe is located about 300-400 kb centromeric of D6S105. It is transcribed into mRNA that is about 8.5 kb in length in many tissues, including peripheral blood leukocytes. The available sequence indicates tha it codes for a zinc finger protein. We propose that there is a reasonable probability that LD5-1 hybridizes with the gene for hereditary hemochromatosis.
Base Sequence↗
A novel intrachromosomal rearrangement in the beta-globin gene found in an African-American family.
We describe here a deletion of 34 nucleotides from the 3' end of the first intervening sequence of the beta-globin gene covering the AGGC splice junction, and the insertion of 32 nucleotides of the delta-globin gene at the same location. This gene rearrangement was detected in three members of an African-American family. The proband, a 28-year-old female, and her mother had a history of chronic anemia. One of her two brothers, who inherited the same gene defect, was apparently healthy with no symptoms of hemolytic anemia. The proband, her father, and her two brothers, including the one who carried the beta-globin gene rearrangement, were found to be heterozygous for alpha-thalassemia-2 (-alpha 3.7). Although the AGGC splice junction is disrupted (AGGC-->AGAT), the invariant AG has remained intact after this gene rearrangement. Our investigations could not detect any defect in RNA processing in the affected beta-globin genes. The discrepancies between the phenotypes and the globin chain synthesis ratios of the mother, her daughter, and her son who inherited the same gene defect at their beta-globin genes, remain unexplained.
Adult↗
[Molecular diagnosis of Gaucher disease in Argentinian patients].
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Adult↗
Chronic granulomatous disease and glutathione peroxidase deficiency, revisited.
We have restudied two kindreds that formed the basis of the original report of autosomal recessive chronic granulomatous disease (CGD) associated with leukocyte glutathione peroxidase deficiency. Case 1 from the original study and the surviving brother of the originally reported case 2 both have severe CGD, with no detectable respiratory burst activity in purified intact neutrophils. However, their leukocytes exhibit normal glutathione peroxidase enzyme activity and gene expression. Examination of phagocyte nicotinamide adenine dinucleotide phosphate (NADPH)-oxidase components known to be defective in CGD reveals no detectable cytochrome b558 nor any membrane activity in a cell-free NADPH oxidase assay system. Molecular analysis of the genes encoding cytochrome b558 subunits shows, in case 1, a C-->T substitution at nucleotide 688 of the gene encoding the gp91-phox subunit of cytochrome b558, resulting in a termination signal in place of Arginine-226. Levels of gp91-phox mRNA are markedly decreased despite normal levels of gene transcription, indicating a post-transcriptional effect of the nonsense mutation on mRNA processing or stability. The X-linked form of CGD developed in this cytogenetically normal female due to the uniform inactivation of the normal X chromosome in her granulocytes, indicated by the expression in her granulocyte mRNA of only one allele of a glucose-6-phosphate dehydrogenase polymorphisms for which she is heterozygous in genomic DNA. Case 2 (of the present study) has distinct mutations in each allele of the p22-phox gene.(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
Homology between a human protein and a protein of the green garden pea.
In screening a rat mucosa cDNA subtraction library, a clone that exhibited a remarkable degree of homology with a previously described cDNA from the green garden pea, designated the 26g pea turgor protein, was found. A partial cDNA sequence from rat and a complete cDNA sequence from human were obtained. The deduced human protein had a molecular weight of 55,285 and was designated antiquitin because of its remarkable level of conservation through evolution. Human antiquitin was 60% homologous to the green pea 26g with only a single amino acid gap in each sequence. The 66 amino acids at the carboxyl ends of the human antiquitin and pea 26g proteins were 86% identical, and one segment of 52 amino acids was 92% identical. A similar partial sequence encoding 164 amino acids has been detected in Caenorhabditis elegans. Yeast DNA was found to have sequences that hybridize with a human antiquitin probe on Southern blotting. Analysis of the amount of mRNA in various rat and human tissues indicated that the largest amounts were found in rat kidney and liver and in cultured human hepatoma cells. Only minimal amounts were detected in human peripheral blood leukocytes, rat lung, or cultured human fibroblasts. Attempts to induce the mRNA by heat-shock, dehydration, ionizing irradiation, or treatment with iron, t-butylhydroperoxide, or glucocorticoids were unsuccessful. The function of the protein remains unknown.
Aldehyde Dehydrogenase↗
Erroneous assignment of Gaucher disease genotype as a consequence of a complete gene deletion.
Two sisters with moderately severe Gaucher disease were diagnosed as having the usually relatively benign 1226G/1226G genotype by examination of DNA amplified from exon 9, where this mutation is located. Because of the discrepancy between the apparent genotype and the phenotype, we suspected that one of the alleles had not amplified. Therefore, the DNA of both parents was examined. The father was heterozygous for the 1226G mutation but the mother did not have this abnormality. It was shown that the mother and both daughters had a deletion of the glucocerebrosidase gene: only about one-half of the polymerase chain reaction (PCR) amplification product of the glucocerebrosidase gene in this region was found, compared to internal controls consisting of the glucocerebrosidase pseudogene and of the adjacent liver pyruvate kinase (PKLR) gene. The appearance of Southern blots developed with full length glucocerebrosidase cDNA probes showed that the band unique to the functional glucocerebrosidase gene had reduced intensity, and no abnormal bands were present after digestion with any restriction endonuclease, indicating that the entire coding region was deleted.
Diseases in Twins↗
Tight linkage of pyruvate kinase (PKLR) and glucocerebrosidase (GBA) genes.
Two polymorphisms, one in the liver-type pyruvate kinase gene (PKLR) and one in the glucocerebrosidase gene (GBA), both of which are on band q21 of chromosome 1, were found to be tightly linked. Each of three Gaucher disease mutations in 112 chromosomes studied was associated with a unique haplotype. With a conservative assumption about the length of time that the Gaucher disease mutation has been present in the Jewish population, we deduce that the genetic distance between these two loci is probably under 0.2 centimorgans. Four haplotypes are produced by these polymorphic loci, but two of these are relatively uncommon because the polymorphic sites are in linkage disequilibrium. Nonetheless these markers are potentially useful in the prenatal diagnosis of pyruvate kinase deficiency in families who have at least one affected child and may also be helpful in heterozygote detection in families with Gaucher disease where a specific mutation producing the disease in unknown.
Base Sequence↗
Two new Gaucher disease mutations.
Recently, a mutation at nucleotide 1193 of the glucocerebrosidase gene was described in a patient with type 1 Gaucher disease. This mutation destroys a TaqI site in a polymerase chain reaction (PCR)-amplified fragment. We used digestion with this enzyme to screen DNA samples from Gaucher disease patients representing 23 previously unidentified alleles and discovered that this site had been destroyed in three samples. However, the mutation that caused this change proved to be a CT substitution at cDNA nucleotide 1192 (Genomic 5408; 359Arg-->End). Fortuitously, another TaqI site was destroyed by a different mutation, a GA mutation at nt 1312 (Genomic 5927; 399AspAsn). Both of these mutations were functionally severe in that they were associated with type 2 (acute neuronopathic) Gaucher disease.
Alleles↗
Glucocerebrosidase mutations in Gaucher disease.
BACKGROUND: Thirty-six mutations that cause Gaucher disease, the most common glycolipid storage disorder, are known. Although both alleles of most patients with the disease contain one of these mutations, in a few patients one or both disease-producing alleles have remained unidentified. Identification of mutations in these patients is useful for genetic counseling. MATERIALS AND METHODS: The DNA from 23 Gaucher disease patients in whom at least one glucocerebrosidase allele did not contain any of the 36 previously described mutations has been examined by single strand conformation polymorphism (SSCP) analysis, followed by sequencing of regions in which abnormalities were detected. RESULTS: Eight previously undescribed mutations were detected. In exon 3, a deletion of a cytosine at cDNA nt 203 was found. In exon 6, three missense mutations were identified: a C-->A transversion at cDNA nt 644 (Ala176-->Asp), a C-->A transversion at cDNA nt 661 that resulted in a (Pro182-->Thr), and a G-->A transition at cDNA nt 721 (Gly202-->Arg). Two missense mutations were found in exon 7: a G-->A transition at cDNA nt 887 (Arg257-->Gln) and a C-->T at cDNA nt 970 (Arg285-->Cys). Two missense mutations were found in exon 9: a T-->G at cDNA nt 1249 (Trp378-->Gly) and a G-->A at cDNA nt 1255 (Asp380-->Asn). In addition to these disease-producing mutations, a silent C-->G transversion at cDNA nt 1431, occurring in a gene that already contained the 1226G mutation, was found in one family. CONCLUSIONS: The mutations described here and previously known can be classified as mild, severe, or lethal, on the basis of their effect on enzyme production and on clinical phenotype, and as polymorphic or sporadic, on the basis of the haplotype in which they are found. Rare mutations such as the new ones described here are sporadic in nature.
Adult↗