Biomedical subjects

A Demina

Publications and source records attributed to A Demina.

11 recordsLinked to original sources

PubMed1998

Six previously undescribed pyruvate kinase mutations causing enzyme deficiency.

Erythrocyte pyruvate kinase deficiency is the most common cause of hereditary nonspherocytic hemolytic anemia. We present 6 previously undescribed mutations of the PKLR gene associated with enzyme deficiency located at cDNA nt 476 G-->T (159Gly-->Val), 884 C-->T (295Ala-->Val), 943 G-->A (315Glu-->Lys), 1022 G-->A (341Gly-->Asp), 1511 G-->T (504Arg-->Leu), and 1528 C-->T (510Arg-->Ter). Two of these mutations are near the substrate binding site: the 315Glu-->Lys (943A) mutation may be involved in Mg2+ binding and 159Gly-->Val (476T) mutation has a possible effect on ADP binding. Four of six mutations produce deduced changes in the shape of the molecule. Two of these mutations, 504Arg-->Leu (1511T) and 510Arg-->Ter (1528T), are located at the interface of domains A and C. One of them (510Arg-->Ter) is a deletion of the C-terminal residues affecting the integrity of the protein. The 504Arg-->Leu mutation eliminates a stabilizing interaction between domains A and C. Changes in amino acid 341(nt 1022) from Gly to Asp cause local perturbations. The mutation 295Ala-->Val (884T) might affect the way pyruvate kinase interacts with other molecules. We review previously described mutations and conclude that there is not yet sufficient data to allow us to draw conclusions regarding genotype/phenotype relationship.

Adenosine Diphosphate↗

PubMed1998

Racial variability in the UDP-glucuronosyltransferase 1 (UGT1A1) promoter: a balanced polymorphism for regulation of bilirubin metabolism?

A polymorphism in the promoter of the UDP-glucuronosyltransferase 1 (UGT1A1) gene has been shown to cause Gilbert syndrome, a benign form of unconjugated bilirubinemia. Promoters containing seven thymine adenine (ta) repeats have been found to be less active than the wild-type six repeats, and the serum bilirubin levels of persons homozygous or even heterozygous for seven repeats have been found to be higher than those with the wild-type six repeats. We have now examined the genotypes in persons of Asian, African, and Caucasian ancestry. Although within the Caucasian ethnic group there is a strong correlation between promoter repeat number and bilirubin level, between ethnic groups we found that this relationship to be inverse. Among people of African ancestry there are, in addition to those with six and seven repeats, also persons who have five or eight repeats. Using a reporter gene we show that there is an inverse relationship between the number of ta repeats and the activity of the promoter through the range of 5-8 ta repeats. An incidental finding was a polymorphism at nucleotide -106, tightly linked to the (ta)5 haplotype. Serum bilirubin levels are influenced by many factors, both genetic and environmental. We suggest that the unstable UGT1A1 polymorphism may serve to "fine-tune" the plasma bilirubin level within population groups, maintaining it at a high enough level to provide protection against oxidative damage, but at a level that is sufficiently low to prevent kernicterus in infants.

Bilirubin↗

PubMed1998

Coincidence of Gaucher's disease due to a private mutation and Ph' positive chronic myeloid leukemia.

We report the case of a 46-year-old female with coexisting type I Gaucher's disease and chronic myeloid leukemia (CML). The diagnosis of Gaucher's disease was made in early childhood by bone marrow biopsy and was recently confirmed by biochemical demonstration of reduced leukocyte beta-glucocerebrosidase activity and the presence of Gaucher cells in a bone marrow aspirate. We analyzed the patient's genomic DNA for the underlying glucocerebrosidase mutations and have found homozygosity for a C-->T transition in cDNA nucleotide 593 (159 Pro-->Leu), presently an undescribed mutation. After initiation of replacement therapy with alglucerase we observed a significant increase of the platelet count in our patient. The diagnosis of CML was based on standard hematological parameters and the detection of the Philadelphia chromosome (Ph). With intermittent treatment with busulfan the patient has remained in chronic phase for nine years. The patient suffered from hepatosplenomegaly and thrombocytopenia, both of which can be caused by Gaucher's disease and CML. The aggravation of skeletal manifestations of Gaucher's disease, which occurred at the time of diagnosis of CML, could be due to increased production of leukocyte-derived glucocerebrosides that were not appropriately degraded because of the genetic beta-glucocerebrosidase deficiency.

Female↗

PubMed1998

Six new Gaucher disease mutations.

Six previously undescribed mutations were identified in 6 unrelated Gaucher disease patients: 437C-->T (107Ser-->Leu), 593C-->T (159Pro-->Leu), 604C-->T (163Arg-->Stop), 1138G-->A (341Ala-->Thr), 1214G-->A (366Ser-->Asn), 1294T-->A (393Trp-->Arg). Five patients were compound heterozygotes and 1 patient was a 593T/593T homozygote. Four patients had type I Gaucher disease with mild clinical phenotypes. Two other patients manifested central nervous system involvement (type II and type III).

Base Sequence↗

PubMed1998

Structure and linkage relationships of the region containing the human L-type pyruvate kinase (PKLR) and glucocerebrosidase (GBA) genes.

Both the L-type pyruvate kinase gene (PKLR) and glucocerebrosidase (GBA) gene are on band q21 of chromosome 1 in humans. Two overlapping P1 bacteriophage clones containing PKLR and GBA were identified and mapped, defining the locations of these two genes as well as those of the GBA pseudogene (psi GBA) metaxin (MTX), the MTX pseudogene (psi MTX), and thrombospondin 3 (THBS3). The distance between the 5' ends of GBA and PKLR was determined to be 71 kb. The direction of transcription PKLR gene was convergent to that of the GBA gene. All 195 Gaucher disease patients homozygous for the 1226G mutation, representing 390 chromosomes with the 1226G mutation, had a PvuII -/- GBA haplotype and a C/C at nt 1705 of the PKLR gene (-/- haplotype). All 56 Gaucher disease patients who were 1226G/84GG compound heterozygotes manifested a -/+ GBA haplotype and 55 of 56 patients were -/+ at PKLR nt 1705. Only 1 patient with 1226G/84GG genotype showed a crossover with the PKLR polymorphism, with a -/- haplotype at nt 1705. Similarly, 9 patients deficient in pyruvate kinase with the PKLR 1529A/1529A genotype were all found to have the same -/- GBA haplotype.

Chromosome Mapping↗

PubMed1997

Molecular analysis of Gaucher disease: distribution of eight mutations and the complete gene deletion in 27 patients from Germany.

Gaucher disease is the most common lysosomal storage disease with a high prevalence in the Ashkenazi Jewish population but it is also present in other populations. The presence of eight mutations (1226G, 1448C, IVS2+1. 84GG, 1504T, 1604T, 1342C and 1297T) and the complete deletion of the beta-glucocerebrosidase gene was investigated in 25 unrelated non-Jewish patients with Gaucher's disease in Germany. In the Jewish population, three of these mutations account for more than 90% of all mutated alleles. In addition, relatives of two patients were included in our study. Restriction fragment length polymorphism analysis and sequencing of PCR products obtained from DNA of peripheral blood leukocytes was performed for mutation analysis. Gene deletion was detected by comparison of radioactively labelled PCR fragments of both the functional beta-glucocerebrosidase gene and the pseudogene. Among the unrelated patients, 50 alleles were investigated and the mutations identified in 35 alleles (70%), whereas 15 alleles (30%) remained unidentified. The most prevalent mutation in our group of patients was the 1226G (370Asn-->Ser) mutation, accounting for 18 alleles (36%), followed by the 1448C (444Lcu-->Pro) mutation, that was found in 12 alleles (24%). A complete gene deletion was present in two alleles (4%). The IVS1+2 (splicing mutation), the 1504T (463Arg-->Cys) as well as the 1342C (409Asp-->His) mutations were each present in one allele (2%). None of the alleles carried the 84GG (frame-shift), 1604A (496Arg-->His) or the 1297T (394Val-->Leu) mutation. This distribution is different from the Ashkenazi Jewish population but is similar to other Caucasian groups like the Spanish and Portuguese populations. Our results confirm the variability of mutation patterns in Gaucher patients of different ethnic origin. All patients were divided into nine groups according to their genotype and their clinical status was related to the individual genotype. Genotype/phenotype characteristics of the 1226G, 1448C, and 1342C mutations of previous studies were confirmed by our results.

Adolescent↗

PubMed1996

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↗

PubMed1995

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↗

PubMed1995

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↗

PubMed1995

Serotypes and subtypes of Neisseria meningitidis: results of an international study comparing sensitivities and specificities of monoclonal antibodies.

An international study supported by the World Health Organization comparing monoclonal antibodies for serotyping and serosubtyping of Neisseria meningitidis strains was performed and the results were assessed in 1992. A collection of 6 serotype-specific (1, 2a, 2b, 4, 14, and 15) and 12 serosubtype-specific (P1.1, P1.2, P1.4, P1.5, P1.6, P1.7, P1.9, P1.10, P1.12, P1.14, P1.15, and P1.16) monoclonal antibodies was provided to 11 participating laboratories throughout the world. Monoclonal antibodies were tested on 85 Neisseria meningitidis strains with known reference results. Whole-cell enzyme-linked immunosorbent assay was used for analysis in 10 of 11 laboratories. The sensitivities and specificities of individual serotype- and subtype-specific monoclonal antibodies were evaluated. Differences in individual laboratories and with individual monoclonal antibodies were assessed. Relatively large differences in sensitivities were achieved in individual laboratories. On the contrary, the specificities remained at high levels in all laboratories. The sensitivities of serotype-specific monoclonal antibodies ranged from 72.0 to 100%. Individual serosubtype-specific monoclonal antibodies showed sensitivities ranging from 64.1 to 98.1%. The most frequent reason for the incorrect results obtained with the monoclonal antibodies were false-negative results. The collaborative study demonstrated that some monoclonal antibodies are not very sensitive. Another study to define the most suitable monoclonal antibodies is planned.

Antibodies, Bacterial↗

PubMed1994

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↗