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Biomedical subjects

E Beutler

Publications and source records attributed to E Beutler.

At least 37 records · Page 2Linked to original sources
PubMed2001

Genetics of iron storage and hemochromatosis.

The regulation of total body iron is important to all organisms. In mammals, the iron content of the body is controlled almost entirely through regulation of absorption. The precise mechanism by which iron is absorbed and the manner in which the absorption is regulated is unknown, but a number of different proteins that are involved either in the transport process itself or its regulation have been identified. These include HFE, a class 1 HLA molecule involved in hereditary hemochromatosis, the divalent metal transporter (DMT-1), hephaestin, the transferrin receptor, and mobilferrin. Iron overload occurs in a number of hereditary disorders including atransferrinemia, aceruloplasminemia, X-linked hereditary sideroblastic anemia, thalassemia major, congenital dyserythropoietic anemia, and various red cell enzyme deficiencies. In Europeans, most cases of hereditary hemochromatosis are due to mutations of the HFE gene. There are two major mutations of this gene c.845G-->A (C282Y) and c.187C-->G (H63D). These mutations have extraordinarily high prevalence in northern Europe and approximately five in a thousand Europeans are homozygous for the 845A mutation. The penetrance of even the homozygous state for the 845A mutation is very low and that for the compound heterozygote 845A/187G, which is also associated with hemochromatosis, is even lower. The reason for the markedly variable penetrance that exists in this disorder remains unknown.

Child↗
PubMed2001

Reference centiles for serum ferritin and percentage of transferrin saturation, with application to mutations of the HFE gene.

BACKGROUND: The gene that causes most cases of hereditary hemochromatosis is designated HFE. Individuals with mutations in the HFE gene may have increased serum iron, transferrin saturation, and ferritin concentrations relative to individuals with the wild-type genotype. METHODS: We generated reference centiles for percentage of transferrin saturation and serum ferritin concentrations in normal (wild-type), healthy Caucasian adults. We then examined transferrin and ferritin concentrations relative to these centiles in 81 individuals homozygous for the major hemochromatosis mutation C282Y and 438 individuals with the compound heterozygous HFE genotype C282Y/H63D. RESULTS: Serum ferritin concentrations, but not percentage of transferrin saturation, in normal, healthy women tended to increase sharply as they progressed through menopause. Transferrin and serum ferritin centiles for normal, healthy females were lower than the corresponding centiles in normal, healthy males. C282Y homozygotes had abnormally high transferrin saturation and serum ferritin values relative to the wild types. Compound heterozygotes appeared to be a mixture of individuals with unexceptional transferrin and ferritin values and those with abnormally large values similar to the homozygotes, with equal proportions of each. CONCLUSIONS: There are age- and sex-related differences in reference centiles for the percentage of transferrin saturation and serum ferritin concentrations in normal, healthy adults. Individuals homozygous for the C282Y mutation in the HFE gene have abnormal transferrin saturation and serum ferritin values relative to the reference population; penetrance with the compound heterozygotes, as reflected by abnormal transferrin and ferritin values, is less than with the homozygotes.

Adult↗
PubMed2000

Molecular characterization of a case of atransferrinemia.

Hereditary atransferrinemia is a rare but instructive disorder that has previously been reported in only 8 patients in 6 families. It is characterized by microcytic anemia and by iron loading, and can be treated effectively by plasma infusions. We now report the first case known in the United States. We determined the sequences flanking the exons of the human transferrin gene and sequenced all of the exons and some of the flanking regions of the patient's DNA and that of her parents. The patient's DNA revealed a 10-base pair (bp) deletion, followed by a 9-bp insertion of a duplicated sequence. There was also a G-->C transversion at complementary DNA (cDNA) nt 1429, predicting that a proline was substituted for the alanine in amino acid position 477 (Ala 477 Pro). The latter mutation occurs at an evolutionarily highly conserved site; 704 control alleles were screened and this point mutation was not found. Each of the patient's transferrin genes contains one mutation, ie, the patient is a compound heterozygote for these mutations, because one was found in each of her parents. In addition to these mutations, which we regard to be causative in the patient's atransferrinemia, a silent polymorphism at cDNA 1572 G-->C was found in exon 13 as well as 2 previously unreported polymorphisms at IVS8 + 62 c-->t and IVS14-4 c-->a. The mutation in nt 1572 and that in intron 8 were common in the general population; the intron 14 mutation is rare.

Adult↗
PubMed2000

Histone H2A-mediated transient cytokine gene delivery induces efficient antitumor responses in murine neuroblastoma.

A major goal of cancer immunotherapy is the induction of a cell-mediated antitumor response in poorly immunogenic malignancies. We tested the hypothesis that this can be achieved by cytokine gene therapy with a novel histone H2A-based transient transfection procedure. This was tested by using cytokine genes encoding for IL-2 and a single chain IL-12 (scIL-12) fusion protein in a recently developed murine neuroblastoma model. Here, we demonstrate that cytokine gene transfer of IL-2 and scIL-12 with histone H2A results in the induction of an antitumor immune response that is superior in some respects to gene transfer with Superfect, a commercially available activated dendrimer commonly used to effect transfection with plasmids. Three lines of evidence support this contention. First, histone H2A-mediated transfection of IL-2 induces a natural killer cell-induced rejection of primary tumors in contrast to Superfect, which produces only a partial reduction in primary tumor growth. Second, the induction of a T cell-mediated protective tumor immunity following gene transfer of scIL-12 is more efficient with the histone H2A-mediated gene transfer because rejection of a lethal wild-type tumor cell challenge is accompanied by the greatest degree of MHC class I-restricted tumor cell killing in vitro. Third, histone H2A-mediated scIL-12 gene therapy induces the greatest release of mIFN-gamma from splenocytes of vaccinated animals in contrast to Superfect and other controls.

Animals↗
PubMed2000

The effect of HFE genotypes on measurements of iron overload in patients attending a health appraisal clinic.

BACKGROUND: The gene that causes most cases of hereditary hemochromatosis is designated HFE. Three mutations exist at this locus at a relatively high gene frequency. OBJECTIVE: To determine the gene frequency of the three HFE mutations and to relate genotypes to various clinical and laboratory variables. DESIGN: Observational study. SETTING: Health appraisal clinic. PATIENTS: 10,198 adults who registered for health appraisal and consented to DNA examination for hemochromatosis. Consenting patients were slightly older and had attained a slightly higher educational level than nonconsenting patients. MEASUREMENTS: Extensive medical history and laboratory tests, including complete blood count, transferrin saturation, and other chemistries; serum ferritin levels; and HFE genotype. RESULTS: In white participants, the gene frequencies were 0.063 for the C282Y mutation, 0.152 for the H63D mutation, and 0.016 for the S65C mutation. Gene frequencies were lower in other ethnic groups. In participants with HFE mutations, the average serum transferrin saturation and ferritin levels were slightly increased, as were mean hemoglobin levels and mean corpuscular volume. A transferrin saturation of 50% had a sensitivity of only 0.52 (95% CI, 0.345 to 0.686) and a specificity of 0.908 (CI, 0.902 to 0.914) for detection of homozygosity. A ferritin level of 200 microg/L in women and 250 microg/L in men had a sensitivity of 0.70 (CI, 0.540 to 0.854) and a specificity of 0.803 (CI, 0.796 to 0.811). The prevalence of iron deficiency anemia was lower in women who carried HFE mutations. CONCLUSIONS: Screening for transferrin saturation and ferritin levels does not detect all homozygotes for the major hemochromatosis mutation. Heterozygotes for HFE mutations had a lower prevalence of iron deficiency anemia.

Ambulatory Care Facilities↗
PubMed2000

Estimating the prevalence of pyruvate kinase deficiency from the gene frequency in the general white population.

Pyruvate kinase (PK) deficiency is the most common cause of hereditary nonspherocytic hemolytic anemia. The prevalence of this deficiency is unknown, though some estimates have been made based on the frequency of low red cell PK activity in the population. An additional 20 patients with hereditary nonspherocytic hemolytic anemia caused by PK deficiency have been genotyped. One previously unreported mutation 1153C-->T (R385W) was encountered. The relative frequency of PK mutations in patients with hemolytic anemia caused by PK deficiency was calculated from the 18 white patients reported here and from 102 patients previously reported in the literature. DNA samples from 3785 subjects from different ethnic groups have been screened for the 4 more frequently encountered mutations-c.1456 C-->T(1456T), c.1468 C-->T(1468T), c.1484 C-->T(1484T), and c.1529 G6A (1529A)-by allele-specific oligonucleotide hybridization. Among white patients the frequency of the 1456T mutation was 3.50 x 10(-3); that of the 1529A mutation was 2.03 x 10(-3). Among African Americans the frequency of the 1456T mutation was 3.90 x 10(-3) The only mutation found in the limited number of Asians tested was 1468T at a frequency of 7.94 x 10(-3). Based on the gene frequency of the 1529A mutation in the white population and on its relative abundance in patients with hemolytic anemia caused by PK deficiency, the prevalence of PK deficiency is estimated at 51 cases per million white population. This number would be increased by inbreeding and decreased by failure of patients with PK deficiency to survive.

Amino Acid Substitution↗
PubMed2000

NADH-ferric reductase activity associated with dihydropteridine reductase.

In mammals dietary ferric iron is reduced to ferrous iron for more efficient absorption by the intestine. Analysis of a pig duodenal membrane fraction revealed two NADH-dependent ferric reductase activities, one associated with a b-type cytochrome and the other not. Purification and characterization of the non-cytochrome ferric reductase identified a 31 kDa protein. MALDI-MS analysis and amino acid sequencing identified the ferric reductase as being related to the 26 kDa liver NADH-dependent quinoid dihydropteridine reductase (DHPR). The NADH-dependent DHPR ferric reductase activity was found to be pteridine-independent since exhaustive dialysis did not reduce activity and heat-inactivation destroyed activity. In intestinal Caco-2 cells, DHPR mRNA levels were found to be regulated by iron. Thus, DHPR appears to be a dual function enzyme, a NADH-dependent dihydopteridine reductase and an iron-regulated, NADH-dependent, pteridine-independent ferric reductase.

Animals↗
PubMed2000

Molecular characterization of a German variant of glucose-6-phosphate dehydrogenase deficiency (G6PD Aachen).

Glucose-6-phosphate dehydrogenase (G6PD) deficiency is an X-chromosome-linked hereditary disorder. Clinically, patients with G6PD deficiency often present with drug- or food-induced hemolytic crises or neonatal jaundice. G6PD is involved in the generation of NADPH and reduced glutathione. In contrast to American, Mediterranean, and African ancestries, only few variants are known from Middle and Northern Europe. We describe the molecular characterization of a distinct variant from the northwestern area of Germany, G6PD Aachen. The sequence of the G6PD gene from three afflicted males was found to be hemizygous at cDNA residue 1089 for a C-->G mutation with a predicted amino acid change of Asn363Lys. The 1089 C-->G point mutation is unique, but produces the identical amino acid change found in a Mexican variant of G6PD deficiency, G6PD Loma Linda. This G6PD-deficient variant is caused by a 1089 C-->A mutation. The 363-amino-acid replacement is located outside a known mutation cluster region between amino acid residues 380 and 450, but may disrupt or weaken dimer interactions of G6PD enzyme subunits.

Adult↗
PubMed2000

A common intron 3 mutation (IVS3 -48c-->g) leads to misdiagnosis of the c.845G-->A (C282Y) HFE gene mutation.

Amplification of the region of the HFE gene that contains the c.845G-->A (C282Y) mutation is usually performed using one amplimer that binds to a sequence in intron 3 and another that binds to a sequence in intron 4. Previously, a mutation that interferes with efficient binding to the intron 4 site has been described. We now find that another common mutation in intron 3, IVS3 -48c-->g, prevents binding of the amplimer to that site. This polymorphism occurs at a gene frequency of 0.128 in the African-American population and at a frequency of only 0.006 in the European population. DNA samples heterozygous for the IVS3 -48c-->g polymorphism and C282Y were undistinguishable from samples homozygous for the C282Y mutation when they were examined by allele-specific oligonucleotide hybridization (ASOH) and showed only a weak normal band when examined by electrophoresis following restriction endonuclease digestion. Although the polymorphism occurs in a DNA sequence almost identical to the intron 3 splice donor site, we found no evidence of alternative splice forms. Moreover, serum iron, transferrin saturation, and serum ferritin levels were normal in subjects heterozygous for the polymorphism. It appears, therefore, that the main importance of this polymorphism is that it may lead to misdiagnosis of heterozygotes for the C282Y mutation as homozygotes. We therefore recommend exonic amplimers that avoid sites that contain polymorphisms and that can be multiplexed for detection of the c.187C-->G (H63D) and c.845G-->A (C282Y) mutations.

Amino Acid Substitution↗
PubMed2000

A new exon 9 glucose-6-phosphate dehydrogenase mutation (G6PD "Rehovot") in a Jewish Ethiopian family with variable phenotypes.

Hereditary nonspherocytic hemolytic anemia (HNSHA) is a rare manifestation of glucose-6-phosphate dehydrogenase (G6PD) gene mutations, caused mainly by mutations located in exon 10 of the G6PD gene and less commonly by mutations in other parts of the gene. A new, exon 9, single-base mutation representing a T --> C transition at cDNA nucleotide 964 was found in three brothers and their carrier mother of Jewish Ethiopian descent. Biochemical characterization of the resultant protein was not performed. Though clinical manifestations included HNSHA in all cases, the severity of hemolysis and the transfusion requirement differed markedly. Severe congenital neutropenia (Kostmann's syndrome)--a disorder never reported before in conjunction with G6PD deficiency--was observed in one case. Levels of white blood cell G6PD activity of the three patients were 0-5% of normal controls. Neutrophil oxidative and bactericidal activities were inherently impaired in the patient with Kostmann's syndrome, but were well preserved in his two siblings.

Anemia, Hemolytic, Congenital Nonspherocytic↗
PubMed2000

Coincidence of Gaucher's disease due to a 1226G/1448C mutation and of an immunoglobulin G lambda multiple myeloma with Bence-Jones proteinuria.

We report about a 58-year-old female with coexisting type-I Gaucher's disease (GD) and multiple myeloma (MM). The diagnosis of GD was made in early childhood by means of bone marrow biopsy and was recently confirmed by analysis of the patient's genomic DNA for the underlying glucocerebrosidase mutations and the identification of the 1226G/1448C genotype. At the age of 24 years, the patient developed massive splenomegaly. Therefore, a splenectomy was performed. No further therapy was necessary for the next 34 years until 1999 when progressive anemia and thrombocytopenia occurred. Additional laboratory analysis revealed high serum protein and immunoglobulin (Ig) G levels and evidence of monoclonal gammopathy and lambda light-chain proteinuria, indicating plasma cell dyscrasia. This diagnosis was confirmed by the detection of osteolytic lesions in skeletal X-rays and a bone marrow biopsy showing an extensive infiltration with Gaucher cells and an increase of plasma cells, which expressed lambda light chains. When examined by means of electron microscopy, typical Gaucher cells, i.e., histiocytes containing tubular-structured cytoplasmatic material and spots of plasma cells with an increase of the endoplasmic reticulum, were found. GD associated with acquired MM has been described 13 times in the literature from 1968 to 1997. Only three of the patients were suffering from IgG myeloma. This distribution of the monoclonal component is in contrast to that of patients suffering from MM alone.

Bence Jones Protein↗
PubMed2000

Large-scale screening for HFE mutations: methodology and cost.

Large-scale detection of mutations at the DNA level requires the development of cost-effective methods for the screening of thousands of samples. Hemochromatosis is an appropriate testing ground for the development of such technologies, and we report the methods that we have developed to screen large numbers of samples using equipment available in most laboratories. We are able to examine DNA samples for two mutations in the HFE gene at a cost of only slightly over $8 per sample, a cost that includes overhead and the approximately 40 hr per week of technician time required to perform the studies. The technologies involved in mutation analysis are evolving rapidly and ultimately more highly automated, lower-cost technologies may become available. At present, however, we find the methodology described to be very suitable for large-scale, low-cost mutation screening.

Base Sequence↗
PubMed2000

Population screening in hereditary hemochromatosis.

Hemochromatosis is a common autosomal recessive condition found in the homozygous state in 1/200-1/400 people of northern-, central-, and western-European origin. It causes increased iron storage, which may lead to liver cirrhosis, liver cancer, heart disease, arthritis, and diabetes in many but not all affected adults, with a higher frequency in males. The condition is easily treated by repeated venesections without side effects but is frequently overlooked. Population screening of adults using iron indices alone or combined with DNA testing has therefore been recommended, but a consensus conference in 1997 recommended that such screening be deferred, owing to uncertainty regarding the extent of clinical disease that may develop in individuals detected by such programs. There was also concern that DNA screening results might be used for discrimination in insurance and occupational settings. Screening family members of patients with evidence of definite iron loading, however, is accepted by all observers. Because serious complications may be overlooked, a more aggressive stance toward case detection in the adult population has been advocated by some observers, realizing that unnecessary treatment might occur. Because additional information regarding the spectrum of clinical disease in homozygotes in now accumulating, a consensus conference in the near future is suggested to consider appropriate policies.

Adult↗
PubMed2000

Three Gaucher-disease-producing mutations in a patient with Gaucher disease: mechanism and diagnostic implications.

As Gaucher disease is an autosomal recessive disorder, most patients are either homozygotes or compound heterozygotes for glucocerebrosidase mutations. We have encountered a patient with three mutations, two c.1226A-->G (1226G, N370S) and one c.1448 T-->C (1448C, L444P). This was shown to be due to a gene conversion event in which the sequence of the glucocerebrosidase pseudogene that includes the 1448C mutation had been imposed on a glucocerebrosidase gene that already had the 1226G mutation. The patient had relatively mild disease which had been discovered after an attack of infectious mononucleosis, a relationship that has been observed previously. If it had not been recognized that this patient had the 1226G/1226G,1448C genotype, prenatal testing might have falsely identified a 1226G,1448C/wt (wild type) fetus as having Gaucher disease.

Adolescent↗