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Christian Oberkanins

Publications and source records attributed to Christian Oberkanins.

14 recordsLinked to original sources
PubMed2005

Investigation of genetic variants of genes of the hemochromatosis pathway and their role in breast cancer.

Iron overload has been noticed as a feature of human breast cancer. Cellular iron uptake is regulated by the hemochromatosis and transferrin receptor system, mutations of which cause the iron storage disease hereditary hemochromatosis. To understand the role of hemochromatosis and transferrin receptor system mutations in breast cancer, we analyzed 19 sequence variations at HFE, TFR1, TFR2, and FPN1 and compared genotype frequencies between cases and controls in a German population. There were 688 breast cancer patients and 724 population-based and age-matched controls. For genotyping, we applied the Hemochromatosis Strip Assay and TaqMan allelic discrimination analyses. In addition to genotype frequencies, we established frequencies of compound genotypes. The frequencies of HFE at His63Asp, Ser65Cys, and Cys282Tyr, and of TFR1 at Ser142Gly minor alleles in this German population were 15.9%, 1.8%, 5.6%, and 46.0%, respectively. No rare variants at 15 more loci at HFE, TFR2, and FPN1 were observed in breast cancer patients. There were no significant differences of allele and genotype frequencies between cases and controls. Triple and quadruple compound genotypes at HFE_His63_Cys282-TFR1_Ser142Gly and HFE_His63_Ser65_Cys282-TFR1_Ser142Gly showed a nonsignificant increase in cases. Although limited by low numbers, an increased prevalence of the HFE Tyr282 minor allele was observed in breast cancer cases with a high number of affected lymph nodes (P = 0.032). Our data suggest that variants of the hemochromatosis-transferrin receptor system have no direct effect on the incidence of breast cancer in Germany. Possible effects on tumor progression and prognosis remain elusive.

Adult↗
PubMed2004

Hb Dhonburi (Neapolis) [beta126(H4)Val-->Gly] identified in a family from northern Iran.

Thalassemias are the most common hereditary diseases in Iran, resulting from synthesis defects in one or more hemoglobin (Hb) subunits. The majority of patients suffer from beta-thalassemia (thal), but cases with microcytic hypochromic anemia and normal electrophoretic patterns are suspected to have alpha- or silent beta-thal. A family from the northern part of Iran, an area highly prevalent for thalassemias, was referred to us for prenatal diagnosis. The hematological data of the father indicated a pattern of beta-thal minor. Reverse hybridization analysis for the most common beta-globin mutations identified IVS-II-1 (G-->A) in the heterozygous state. The maternal laboratory data indicated a case more compatible with alpha-thal. Iron deficient anemia was ruled out, and common alpha-thal point mutations and deletions were investigated. As no mutation was detected, chain synthesis was performed and showed an alpha/beta chain ratio of 2.1, that was in the range of beta-thal minor. DNA sequencing of the entire beta-globin gene identified a heterozygous GTG-->GGG (Val-->Gly) mutation at codon 126, also known as Hb Dhonburi (Neapolis). Prenatal diagnosis of the fetal DNA showed the absence of the IVS-II-1 and codon 126 anomalies. This result demonstrates the importance of screening of individuals with mild microcytic hypochromic anemia for both alpha- and silent beta-thal mutations.

Family↗
PubMed2004

Reverse hybridization vs. DNA sequencing in the molecular diagnosis of Familial Mediterranean fever.

Familial Mediterranean fever (FMF) is an autosomal recessive inflammatory disorder predominantly affecting people living in or originating from areas around the Mediterranean Sea. It is caused by a number of mutations within the MEFV gene, which differently affect the severity of the disease phenotype. Because patients usually present with rather nonspecific clinical symptoms, MEFV genotyping can confirm and refine FMF diagnosis and improve treatment of affected individuals. We have performed a method comparison study on 100 Lebanese FMF patients to evaluate the potential of a rapid reverse-hybridization teststrip-based assay (FMF StripAssay) to serve as a first-line screening test for our population. When results obtained by reverse-hybridization and DNA sequencing of exons 2, 3, 5, and 10 were compared, the FMF StripAssay identified 144/149 mutations, and correctly typed all 12 different MEFV mutations covered. We conclude that reverse-hybridization provides a very rapid, accurate and easy-to-perform screening method, and, in combination with more comprehensive diagnostic methods, represents an efficient strategy for FMF genotyping.

Cytoskeletal Proteins↗
PubMed2004

Elevated coagulation factor VIII and the risk for recurrent early pregnancy loss.

Inherited and acquired thrombophilia are associated with recurrent pregnancy loss. Recently, an increased risk for thromboembolic disease was described for patients with elevated coagulation factor VIII, but it is unknown whether there is also an association to early pregnancy loss. We therefore evaluated the relation between recurrent early pregnancy loss and levels of coagulation factor VIII. We enrolled 49 unrelated Caucasian women with a history of 2-6 early pregnancy losses and 48 healthy controls, who had delivered at least one term infant and had never experienced pregnancy loss. We determined factor V Leiden-, G20210A prothrombin-, MTHFR C677T- and A1298C-gene mutations, levels of antithrombin, protein C, protein S, factor VIII, C-reactive protein and antiphospholipid antibodies. There was a significantly higher rate of pregnancy losses in women with Antiphospholipid Syndrome (p = 0.043). Furthermore, plasma levels of coagulation factor VIII were significantly higher in cases than in controls (130.5 IU/dl +/- 25.4 vs 119.5 IU/dl +/- 24.1; p = 0.032) and appeared independent of C-reactive protein (R = 0.146, p = 0.323 in cases; R = -0.028, p = 0.850 in controls). The relative risk for recurrent pregnancy loss in women with factor VIII levels above 151 IU/dl (90(th) percentile of controls) was 2.5 (0.7 - 8.9, 95 percent confidence interval), for levels above 156 IU/dl (95(th) percentile of controls) 3.9 (0.8 - 20.0, 95 percent confidence interval). Elevated maternal plasma levels of coagulation factor VIII tend to be associated with an increased risk for recurrent early pregnancy loss.

Abortion, Habitual↗
PubMed2003

Simultaneous detection of multiple familial hypercholesterolemia mutations facilitates an improved diagnostic service in South african patients at high risk of cardiovascular disease.

AIM: DNA testing can provide a definitive diagnosis of familial hypercholesterolemia (FH), even in the absence of the clinical characteristics of this inherited cardiovascular disease (CVD) subtype. Our aim was to design a rapid diagnostic assay capable of simultaneously analyzing seven point mutations in the low-density lipoprotein receptor (LDLR) gene, which occur at high frequency in South African FH patients. METHODS: The test is based on multiplex DNA amplification and hybridization to membrane strips presenting a parallel array of immobilized allele-specific oligonucleotide probes. RESULTS: A reverse-hybridization assay for genotyping LDLR point mutations D154N, D200G, D206E, C356Y, G361V, V408M, and P664L was set-up and validated using pretyped human DNA samples, as well as recombinant plasmid clones containing mutant alleles. The procedure is rapid (6 hours) and may be automated to a large extent. CONCLUSIONS: The new FH strip-assay forms an important part of the comprehensive cardiovascular genetic screen offered routinely to high-risk population groups in South Africa. A genetic approach based on FH testing in conjunction with other 'genetic' CVD risk factors is feasible and justified, since the spectrum of disease-related mutations have been defined to a large extent in the genetically distinct population groups of South Africa. Knowledge of a significantly increased CVD risk due to the presence of gene variations, which can be targeted for risk reduction by the avoidance of relevant environmental risk factors and the appropriate treatment, provides a powerful message to motivate people into implementing preventative measures based on their genetic profile.

Amino Acid Substitution↗
PubMed2003

Rapid genetic testing for Gaucher disease by reverse hybridization.

BACKGROUND: We evaluated a reverse hybridization method for the simultaneous detection of nine mutations that are associated with Gaucher disease. RESULTS AND CONCLUSION: Results were in agreement with those obtained by a polymerase chain reaction-restriction digestion method. The hybridization method produced results more quickly and with less operator input.

Gaucher Disease↗
PubMed2003

Plasminogen activator inhibitor 1 4G/5G polymorphism and coagulation factor XIII Val34Leu polymorphism: impaired fibrinolysis and early pregnancy loss.

BACKGROUND: A successful outcome of pregnancy depends on proper placental formation. In the very beginning of this process, trophoblast invasion and fibrin deposition into the wall of the decidual veins play an important part. Two polymorphisms, coagulation factor XIII (FXIII) Val34Leu and plasminogen activator inhibitor 1 (PAI-1) 4G/5G, interfere with fibrin cross-linking and regulation of fibrinolysis and may therefore contribute to early pregnancy loss. METHODS: We enrolled 49 unrelated Caucasian women with a history of two consecutive or three to six nonconsecutive early pregnancy losses and 48 unrelated parous healthy controls without a history of pregnancy loss and evaluated them for the following genetic variants: the factor V Leiden and prothrombin G20210A gene mutations, the methylenetetrahydrofolate reductase C677T and A1298C polymorphisms, and the PAI-1 4G/5G and FXIII Val34Leu polymorphisms. RESULTS: For the isolated occurrence of PAI-1 4G/5G or FXIII Val34Leu, we found no statistically significant difference between cases and controls. For homozygosity of either or compound carrier status of both mutations, the overall relative risk for early pregnancy loss was significantly increased (odds ratio = 2.4; 95% confidence interval, 1.1-5.5; P = 0.032). We observed no statistically relevant association of any of the other tested mutations with early pregnancy loss. CONCLUSION: Homozygosity for PAI-1 4G or FXIII 34Leu polymorphisms as well as compound carrier status is associated with early pregnancy loss.

Abortion, Habitual↗
PubMed2003

Prevalence of C282Y and E168X HFE mutations in an Italian population of Northern European ancestry.

BACKGROUND AND OBJECTIVES: In Italy, the prevalence of C282Y is lower than in Northern European countries. We hypothesized a higher prevalence of C282Y in Northern than in Southern Italian populations. We previously identified a nonsense mutation (E168X) in hemochromatosis probands originating from a region in the north-west of Italy. We aimed to define the prevalence of C282Y and E168X in that region and the origin of the E168X mutation by haplotype analysis. DESIGN AND METHODS: Six-hundred and six blood donors were investigated for C282Y, H63D, S65C and E168X mutations by polymerase chain reaction (PCR)-restriction assays. Three hundred were also tested for rare HFE and TFR2 mutations by reverse-hybridization test strips. D6S265, D6S105 and D6S1281 microsatellites were analyzed to define E168X 6p-associated haplotypes. RESULTS: One C282Y homozygote, thirteen C282Y/ H63D compound heterozygotes, four E168X heterozygotes and three E168X/H63D compound heterozygotes were found. The allele frequencies of C282Y, H63D, S65C, and E168X were 4.7%, 14.9%, 0.74% and 0.58%, respectively. INTERPRETATION AND CONCLUSIONS: The prevalence of C282Y in the region investigated was much higher than that previously reported in Italy. This finding is probably due to the heavy Celtic component of this north-western population and suggests that in populations of Northern Italian descent screening studies for hemochromatosis could be cost-effective. The prevalence of E168X in this region, although low, suggests that the mutation probably originated here many years ago and its frequency increased as a result of a local founder effect. Given its severity, we suggest that the E168X mutation should be searched for in all hemochromatosis patients of Northern ancestry with an incomplete HFE genotype.

Female↗
PubMed2003

Analysis of HFE and TFR2 mutations in selected blood donors with biochemical parameters of iron overload.

BACKGROUND AND OBJECTIVES: Hereditary hemochromatosis is a recessive condition characterized by iron accumulation in several organs, followed by organ damage and failure. The disorder is prevalently due to C282Y and H63D mutations in the HFE gene, but additional HFE and TFR2 mutations have been reported. Early iron overload may be assessed by biochemical parameters such as increased transferrin saturation and serum ferritin. DESIGN AND METHODS: Taking advantage of the collection of 178 DNA samples selected for increased transferrin saturation (>50% in males and >45% in females) from a previous large scale screening of Italian blood donors, we simultaneously assessed the presence of 14 hemochromatosis-associated molecular defects (11 of HFE and 3 of TFR2) by a reverse hybridization-based strip assay. RESULTS: In the series studied the overall C282Y allele frequency was 9% and that of the H63D and S65C was 22.2% and 1.4%, respectively. One rare HFE allele (E168Q), but no TFR2 mutation was detected. When checked at a second examination, transferrin saturation was significantly higher in C282Y homozygotes, H63D/ C282Y compound heterozygotes and H63D homozygotes as compared to wild-type subjects (p<0.05). INTERPRETATION AND CONCLUSIONS: Our results confirm previous findings on C282Y and H63D mutations in Italy, show that the C282Y allele frequency is enriched in samples selected for altered iron parameters, and that a few rare genotypes are present in Northern Italy. None of the known TFR2 mutations was identified in this series confirming the preliminary indication of their rare occurrence. Subjects with hemochromatosis-associated genotypes show a persistently higher mean transferrin saturation than do those with wild type genotypes.

Blood Donors↗
PubMed2003

alpha-globin gene deletion and point mutation analysis among in Iranian patients with microcytic hypochromic anemia.

We tested 67 Iranian individuals, presenting with low mean corpuscular volume (MCV) and mean corpuscular hemoglobin (MCH) levels, normal hemoglobin electrophoresis and iron status, for the presence of twelve common alpha-thalassemia gene deletions and point mutations. Five different mutations (-alpha(3.7), -alpha(4.2), --MED, -(alpha)20.5, Hb Constant Spring) were identified in a total of 43 cases

Anemia, Hypochromic↗