[Molecular genetic characterization of chronic lymphocytic leukemia aggressivity in Czech patients: a nucleotide variability of genes coding for heavy chain of immunoglobulin]. / Molekulárne -genetická charakterizace agresivity chronické lymfocytárni leukémie u ceských pacientu: nukleotidová variabilita genu kódujících syntézu tezkého retezce imunoglobulinu.

BACKGROUND: Chronic lymphocytic leukemia is a heterogeneous disease manifesting with a variable clinical course. It is evident from many studies, that the division into two main prognostic categories is possible on the basis of mutation status of the immunoglobulin heavy-chain gene. The objective of our work was to identify a presence or absence of IgVH gene mutations in B-CLL patients which are monitored or treated on hematological clinics and to determine the presence of individual D and J, subgenes in malignant population of B-cells. METHODS AND RESULTS: A nucleotide sequence of IgVH gene of neoplastic cells was analyzed by appropriate molecular-genetic methods. RNA/cDNA was collected from 358 patients and a spectrum of individual subgenes translocations was identified. Our results show that 56.3% of patients manifested an unmutated variable (VH) segment. It is expected from the published data that this group of patients will suffer from aggressive course of the disease and will exhibit a substantially shorter survival in comparison to patients possessing somatic hypermutations. An expanded population of leukemic B-cells showed increased occurrence of clones whose variable segments belong to three different families. VH3 alleles are the ones most frequently used. A frequency of unmutated alleles is prominently shifted into families with V I homology. The preferred "diversity and joining" segments are D3, D2 and JH 4 and JH 6. CONCLUSIONS: The analysis of heavy chain immunoglobulin gene after recombinant VH-D-J11 segments translocation belongs to a standard hematooncological investigation. The results are an important prognostic criterion for prediction of expected disease aggressivity and for a minimal residual disease monitoring.

New promoter mutations in the low-density lipoprotein receptor gene which induce familial hypercholesterolaemia phenotype: molecular and functional analysis.

Low-density lipoprotein receptor (LDLR) is a cell-surface glycoprotein that mediates specific uptake and catabolism of plasma LDL. Mutations located in the coding region of the LDLR gene affect the structure and function of the protein and cause familial hypercholesterolaemia (FH). Mutations in the regulatory regions of the gene are rare, but in some cases have been shown to alter the transcriptional activity of the gene and cause the FH phenotype as well. Adult heterozygous FH individuals have a markedly raised plasma cholesterol that is associated with accelerated atherosclerosis and premature coronary heart disease. The aim of this study was the functional characterization of a promoter mutation in the LDLR gene in one family from the register of Czech FH subjects. Molecular screening revealed that three members of this family carried a -27C > T nucleotide transition in the promoter sequence (calculated from the start of transcription). All three manifested a heterozygous FH phenotype. This new mutation is located between the TATA box and sterol-dependent regulatory element repeat 3. Using a luciferase reporter assay system, we analysed the transcriptional efficiency of the normal and mutant alleles. The mutation reduced promoter activity to background level. Another new promoter mutation -60C > T was identified in an unrelated patient in the conserved nucleotide sequence of the sterol-dependent regulation element repeat 2 which virtually abolished the promoter activity. We assume a causal effect of this -60C > T transition on the basis of its position in the promoter sequence.

Prevalence of endothelial nitric oxide synthase gene polymorphisms in patients with atopic asthma.

BACKGROUND: Asthma is a common multifactorial disease, the aetiology of which is attributable to both environmental and genetic factors. The endothelial nitric oxide synthase (NOS3) gene has been implicated in asthma pathogenesis. OBJECTIVE: This study investigated associations of 27 base-pair tandem repeat polymorphism in intron 4 and the Glu298Asp (G894T) variant of the NOS3 gene with atopic asthma in a Czech population. METHODS: Polymerase chain reaction was used to determine the NOS3 genotypes in subjects with atopic asthma (n = 163) and random controls (n = 209). RESULTS: The NOS3 allele or genotype distributions did not differ significantly between the control and asthma groups. However, the common genotype (bb) of the NOS3 polymorphism in intron 4 was found to be significantly associated with total IgE levels (P = 0.006), specific IgE levels for feathers (P = 0.0002) and a positive skin prick test for hay (P = 0.004). In one atopic patient, we identified an additional 27-bp repeat in the NOS3 gene (NOS3c), which occurred in heterozygous combination with the NOS3b allele (NOS3b/c genotype). In addition, we describe a new polymorphism (A5495G) in the NOS3 gene, which was in almost complete linkage disequilibrium with the NOS3 repeat polymorphism in intron 4. The Glu298Asp variant was not associated with asthma and/or related atopic phenotypes in our study. CONCLUSION: Neither the NOS3 'b' allele nor the NOS3 'b/b' genotype showed any general association with atopic asthma, but they were associated with atopy-related phenotypes. We conclude that the NOS3 gene polymorphisms may act as disease modifiers in atopic asthma phenotype in our population.

Spectrum of low density lipoprotein receptor mutations in Czech hypercholesterolemic patients.

The aim of our study was to define mutations causing familial hypercholesterolemia (FH) phenotype in Czech hypercholesterolemic individuals. A combination of heteroduplex analysis, SSCP, DGGE, DNA sequencing and PCR/restriction analysis was used for this purpose. Molecular searching in the promoter region and coding sequence of the low density lipoprotein receptor (LDLR) gene in 130 patients from 68 unrelated families resulted in the identification of 37 sequence variations. Thirty of them are most likely disease causing mutations. Nineteen mutations were novel (two nonsense, five missense, six nucleotide(s) insertions and six nucleotide(s) deletions). Their pathological effect can be predicted on the basis of their position with respect to previously reported mutations with an estimated reduction of the receptor activity and/or premature termination of translation. These results expand our knowledge of mutations responsible for FH. Seven nucleotide variations were characterized as silent polymorphisms. Hum Mutat 18:253, 2001.

Polymorphisms in the RAGE gene influence susceptibility to diabetes-associated microvascular dermatoses in NIDDM.

To examine genetic polymorphism in the complete sequence of the Receptor of Advanced Glycation End products (RAGE) gene and its possible associations with diabetes-associated microvascular dermatoses (DAMD). Further, to analyze the distribution of individual genotype combinations on the particular polymorphic loci in the RAGE gene. A part of the RAGE gene spanning a region from -4 to 3334 bp was analyzed on a set of 45 subjects with non-insulin dependent diabetes mellitus (NIDDM) and parallel DAMD by means of PCR with subsequent heteroduplex and single-strand conformation polymorphism (SSCP) analyses. Allele frequencies and genotype combinations of novel common polymorphisms were determined in an associations study comprising four groups of subjects (n=390). Fourteen novel polymorphisms (R77C, V89V, 718G/T, 1704G/T, 1727A1728ins, H305Q, S307C, 2117A/G, 2184A/G, 2245G/A, 2249A/G, 2741G/A, and 3089ACdel) and one described previously (G82S) were identified. Significant association with microvascular dermatoses (MD) irrespective of NIDDM were found for exon mutation 82S (P= .004, after a correction for the number of comparisons P(corr) < .05) and marginally significant for intron variant 1704T (P= .032, P(corr)> .05). Calculated odds ratios for 82S and 1704T were 4.73 (95% CI, 1.51 to 14.77) and 1.73 (95% CI, 0.93 to 3.22), respectively. Certain individual genotype combinations of G82S, 1704G/T, and 2184A/G were significantly associated with the presence of MD (P= .00647) both in diabetic and non-diabetic study populations. The two novel polymorphisms (1704G/T and 2184A/G) together with the G82S were shown to influence the susceptibility to MD independent of diabetes itself.

Novel dystrophin mutations revealed by analysis of dystrophin mRNA: alternative splicing suppresses the phenotypic effect of a nonsense mutation.

The complete dystrophin mRNA sequence has been analyzed in 20 Duchenne muscular dystrophy and Becker muscular dystrophy patients. In 13 cases, deletions in mRNA were detected using reverse transcription-polymerase chain reaction and in another seven cases, point mutations were found using the protein truncation test. Sixteen patients diagnosed with Duchenne muscular dystrophy showed the presence of deletions or of nonsense point mutations. From four patients with the Becker muscular dystrophy phenotype, three cases were associated with deletions conserving the translational frame and one was associated with a nonsense mutation E1110X. In the case of the E1110X mutation, an alternative splicing of dystrophin mRNA (3485-3640del) was detected in this patient which included the E1110X mutation site (nucleotide 3536) and did not change the translation reading frame. Individual nonsense point mutations were characterized by sequence analysis, which showed five novel mutations with respect to those reported in the Cardiff Human Gene Mutation Database http://uwcm.web.cf.ac.uk/uwcm/mg/hgmd0.html and the Leiden muscular dystrophy pages http://www.dmd.nl/.

[Screening for mutations in apolipoprotein B genes in a group of patients with hyperlipoproteinemia]. / Screening mutací v genu pro apolipoprotein B v souboru pacientu s hyperlipoproteinémií.

BACKGROUND: Familial defective apolipoprotein (apo) B-100 (FDB) is a common inherited metabolic disorder. Reduced binding of the apo B-100, the major protein of LDL particles, to LDL receptor results in marked hypercholesterolemia. FDB is caused particularly by an arginine to glutamine substitution at the codon for amino acid 3500 of the apo B-100. The aim of this study was to determine mutations potentially responsible for hypercholesterolemia in the apo B gene and to estimate their frequency in the group of Czech hyperlipidemic patients. METHODS AND RESULTS: The groups of 169 unrelated patients with primary isolated hypercholesterolemia (total cholesterol > or = 6.5 mmol/l, triglycerides < or = 2.3 mmol/l) and 58 unrelated patients with combined hyperlipoproteinemia (total cholesterol > or = 6.5 mmol/l, triglycerides > 2.3 mmol/l) were screened for mutations in codon 3500 region of the apolipoprotein B gene by denaturing gradient gel electrophoresis. Mutation R3500Q was detected in 20 patients with isolated hypercholesterolemia (11.8%) and in 2 patients with combined hyperlipoproteinemia (3.4%). No other mutations were found. CONCLUSION: The frequency of FDB in our group of patients with primary isolated hypercholesterolemia is high when compared with data published in other countries. We suggest that all patients with primary isolated hypercholesterolemia (total cholesterol > or = 6.5 mmol/l) in the Czech Republic should be analysed for the presence of mutation R3500Q in the apo B gene.

[The program for detection and treatment of patients with familial hypercholesterolemia (MedPed FH) in the Czech Republic]. / Program vyhledávání a lécby nemocných s familiární hypercholesterolémií (MedPed FH) v Ceské Republice.

The authors present an international MedPed project (Make early diagnoses to prevent early deaths in medical pedigrees) the task of which is to increase the number of patients with familial lipid disorders identified and adequately treated all over the world. This will lead to significant decrease of premature deaths from coronary artery disease. Primary effort has been focused on familial hypercholesterolemia. The realization of MedPed program in Czech Republic is described.

[Interaction of mutations M235T of the gene for angiotensinogen and Taq I 8,000 in the gene for endothelin-1 at the onset of essential hypertension]. / Interakce mutace M235T genu pro angiotenzinogen a mutace Taql 1 8000 v genu pro endotelin-1 pri vzniku esenciální hypertenze.

BACKGROUND: Identification of mutations contributing to the pathogenesis of essential hypertension performs to understand deeper consequences of developing pathophysiological changes, to value individual risk of hypertension in the preclinical stages and, regarding the observed genotype, to choose optimum therapy. The aim of the study was to prove the existence of difference in double genotype occurrence of polymorphic candidate genes between normotensive and hypertensive subjects. METHODS AND RESULTS: A sample of Czech population (398 individuals), 192 normotensives (age of 45.87 +/- 3.0, BMI = 25.44 +/- 3.31 kg x m2) a 206 hypertensives (age of 48.71 +/- 8.42, BMI = 27.18 +/- 4.16 kg x m(-2)) was genotyped at angiotensinogen (AGT, M235T polymorphism, exon 2) and endothelin-1 (EDN-1, Taq I 8000 polymorphism, intron 4) genes by PCR methods. Experimental schedule was case-control. Chi2 and Fisher-exact test were used for statistical analyses. M-allele of angiotensinogen gene was associated with essential hypertension (p = 0.0111). Allele (-) alone at endothelin-1 gene was associated with essential hypertension with marginal significance (p = 0.0622). A significant loss of heterozygotes MT (M235 AGT) at homozygote (--) at endothelin-1 gene (p = 0.0025) as well as a significant increase of allele (-) of endothelin-1 gene at homozygote MM at angiotensinogen gene (p = 0.0034) were found. CONCLUSIONS; Interaction of two polymorphic genetic variants of angiotensinogen and endothelin-1 genes was found. From the pathophysiological point of view, the fact may be explained as a stream to compensate the influence of variability of other genes more causatively conditioning essential hypertension.

[Direct detection of mutations in the LDL receptor gene in patients with familial hypercholesterolemia]. / Prímá detekce mutací v genu pro LDL receptor u pacientu s familiární hypercholesterolémií.

BACKGROUND: Familial hypercholesterolemia is one of the most frequent hereditary metabolic diseases. As a result of the functional disorder of the molecule of the LDL receptor LDL cholesterol is not sufficiently eliminated from the blood stream and exerts an atherogenic effect. The objective of the study was to introduce direct detection of mutations in the gene for the LDL receptor and characterize the spectrum of mutations in the Czech population. METHODS AND RESULTS: The authors analyzed a group of 84 unrelated patients where on the basis of clinical and biochemical criteria the diagnosis of FH was established. From the group 12 patients were eliminated (14.3%) where a mutation 3500 in the gene for apolipoprotein (apo) B-100 was detected. This mutation is most frequently the cause of a familial defect of apo B-100 (FDB), which cannot be differentiated clinically or biochemically from FH. In the LDL receptor gene a total of 11 mutations were found in 14 unrelated patients (16.7%), incl. 7 mutations not described hitherto. CONCLUSIONS: This is the first systematic characteristic of the spectrum of mutations in the LDL receptor gene in the Czech population. Molecular genetic analysis of the gene for the LDL receptor in affected families can contribute towards early assessment of the diagnosis of FH and thus to prevention of life threatening cardiovascular episodes in asymptomatic subjects.

Characterization of two nonsense mutations in the human dystrophin gene.

Forty Duchenne muscular dystrophy patients from the province of Moravia in the Czech Republic, who were previously found negative for large deletions in the dystrophin gene, were tested for the presence of point mutations in selected exons. Besides several intron and exon polymorphisms, two cases of nonsense mutations were detected in exon 70, thus causing the loss of the C-terminal domain of dystrophin. One of these, the mutation, S3365X, is newly reported here while the other, R3381X, has been described previously. These mutations, only 16 bp distant from each other, have a very different impact on the mental abilities of the corresponding patients.

Mutation and haplotype analysis of phenylalanine hydroxylase alleles in classical PKU patients from the Czech Republic: identification of four novel mutations.

Mutations, haplotypes, and other polymorphic markers in the phenylalanine hydroxylase (PAH) gene were analysed in 133 unrelated Czech families with classical phenylketonuria (PKU). Almost 95% of all mutant alleles were identified, using a combination of PCR and restriction analysis, denaturing gradient gel electrophoresis (DGGE), and sequencing. A total of 30 different mutations, 16 various RFLP/VNTR haplotypes, and four polymorphisms were detected on 266 independent mutant chromosomes. The most common molecular defect observed in the Czech population was R408W (54.9%). Each of the other 29 mutations was present in no more than 5% of alleles and 13 mutations were found in only one PKU allele each (0.4%). Four novel mutations G239A, R270fsdel5bp, A342P, and IVS11nt-8g-->a were identified. In 14 (5.1%) alleles, linked to four different RFLP/VNTR haplotypes, the sequence alterations still remain unknown. Our results confirm that PKU is a heterogeneous disorder at the molecular level. Since there is evidence for the gene flow coming from northern, western, and southern parts of Europe into our Slavic population, it is clear that human migration has been the most important factor in the spread of PKU alleles in Europe.

[Detection of extensive deletions and duplications in the dystrophin gene]. / Detekce rozsáhlých delecí a duplikací v dystrofinovém genu.

Dystrophin is a cytoskeletal protein, defects of which results in Duchenne or Becker muscular dystrophy (DMD or BMD). About 70% of all DMD and BMD cases is caused by large deletions and duplications in the dystrophin gene. Therefore, their detection at the DNA and mRNA level is the analysis of the first choice which is undergone by our patients at the molecular level. Methods which have been introduced in our laboratory for this purpose-multiplex PCR and RT-PCR-are subject of this communication.

Distribution of dystrophin gene deletions mapped by multiplex PCR in the Moravian population.

Twenty two Duchenne muscular dystrophy (DMD) patients from the province of Moravia, Czech Republic, were tested for the presence of dystrophin gene rearrangements using multiplex polymerase chain reaction (PCR). Using primer pairs for amplification of two promoter regions and 27 exons, 11 patients were found positive for deletions spanning one or more exons. In all these cases, the deletions affected the distal part of the dystrophin gene, beginning from exon 44 but not reaching exon 60.

Phenylketonuria mutations and their relation to RFLP haplotypes at the PAH locus in Czech PKU families.

A detailed study of the mutant phenylalanine hydroxylase (PAH) gene from the eastern part of the Czech Republic (Moravia) is reported. A total of 190 mutant alleles from 95 phenylketonuria (PKU) families were analyzed for 21 prevalent Caucasian mutations and restriction fragment length polymorphism/variable number of tandem repeats (RFLP/VNTR) haplotypes. Eighty per cent of all mutant alleles were found to carry 11 mutations. The most common molecular defect was the mutation R408W (55.3%), with a very high degree of homozygosity (34.6%). Each of four other mutations (R158Q, R243X, G272X, IVS12nt1) accounted for more than 3% of PKU alleles. Rarely present were mutations IVS10nt546 (2.6%), R252W (2.6%), L48S (2.1%), R261Q (1.6%), Y414C (1.0%) and 165T (0.5%). Mutations that have been predominantly described in southern Europe (IVS7nt1, A259V, Y277D, R241H, T278N) were not detected. A total of 14 different mutant haplotypes were observed. Three unusual genotype-haplotype associations were identified (R158Q on haplotypes 2.3 and 7.8 and R252W on haplotype 69.3). There was a strong association between the mutation R408W and haplotype 2.3 (54.7%). Heterogeneity was found at mutations R408W (haplotypes 2.3 and 5.9), R158Q (haplotypes 4.3, 2.3 and 7.8) and IVS10nt546 (haplotypes 6.7 and 34.7). The molecular basis of PKU in the Moravian area appears to be relatively homogeneous in comparison with other southern and western European populations, thus providing a good starting point for prenatal diagnosis and early clinical classification.

[Advances in the diagnosis of phenylketonuria with the introduction of direct detection of PAH gene mutation]. / Pokroky v diagnostice fenylketonurie zavedením prímé detekce mutací v PAH genu.

BACKGROUND: Phenylketonuria is as regards the genotype a very heterogenous disease. Successful prenatal and postnatal DNA diagnosis calls for knowledge of different mutations in a given population. The objective of the investigation was to introduce direct detection of 21 mutations in the gene for phenylalanine hydroxylase and to find the distribution and frequency of these mutations in the population of northern and southern Moravia. METHODS AND RESULTS: The authors analyzed a group of 95 patients where according to phenotypic classification classical phenylketonuria was involved which comprised 190 mutant alleles. The presence of mutations was assessed by means of a polymerase chain reaction of a Perkin Elmer DNA Thermal Cycler 480. From the total number of 21 mutations which were sought, 11 were identified in our population, which accounts for 80% of all mutations. It was revealed that mutation R408W is found in 55.3% of our patients. Twenty per cent of the mutations are still unknown. CONCLUSIONS: This investigation laid the foundations for direct DNA diagnosis of phenylketonuria in the Czech Republic. The results assembled in the Moravian region suggest that our population is as regards genotypes relatively homogenous. This gives great hope of successful prenatal diagnosis and postnatal genotype classification.

Trans-diamminedichlorplatinum (II)-modified probes for detection of picogram quantities of DNA.

A novel simple nonradioactive method for detection of specific nucleotide sequences has been developed. This method consists of the hybridization of a target DNA with a DNA probe modified with trans-diamminedichlorplatinum(II) (trans-DDP) followed by detection of DNA/DNA hybrids with affinity-isolated anti-DNA-trans-DDP antibodies and poly-horseradish peroxidase-protein A conjugate. Major advantages of this approach are the low cost and the extreme simplicity of the labeling procedure, which involves only mixing of the reagents. The sensitivity of the proposed technique is sufficient to detect 0.8 pg of DNA in Southern blot hybridization and 25 fg in dot hybridization and permits colony screening.

Differential sensitivity of CG and CCG DNA sequences to ethionine-induced hypomethylation of the Nicotiana tabacum genome.

Plant DNA is distinguished from the DNA of all other organisms by its high content of 5-methylcytosine (5mC). 5mC levels may amount to 30% of total cytosines, distributed between the sequences CG and CXG. The results presented here show that the methylation status of CXG sequences could be influenced by culturing tobacco tissues on subtoxic concentrations of ethionine. The hypomethylating effect of ethionine, evaluated as the capability of MspI or HpaII to cleave the DNA, proved to be rather specific for CCG and differed from that of 5-azacytidine which did not discriminate between CG and CXG sequences.

Isolation and characterization of two middle repetitive DNA sequences of nuclear tobacco genome.

Two DNA sequences, R8.1 and R8.3, representing two distinct classes of tobacco genomic repeated DNA, were cloned and characterized by Southern blot analysis. Both R8.1 and R8.3 were found to be homologous to the Nicotiana tomentosiformis component of the allotetraploid Nicotiana tabacum genome, and each of them represents about 0.3% of nuclear DNA. The R8.1 and R8.3 differ in the mode of distribution in chromosomes, as revealed by in situ DNA/DNA hybridization.