Biomedical subjects

Paal Skytt Andersen

Publications and source records attributed to Paal Skytt Andersen.

11 recordsLinked to original sources

PubMed2006

[Long QT syndrome--genes, mechanisms and risks. Indication for genetic family screening?].

Inherited long QT syndrome (LQTS) is a cardiac disease characterised by episodes of ventricular tachyarrhythmia, presenting as syncope or sudden death. Untreated, the annual mortality rate is 1-2%. Sudden death has been reported as the first manifestation of the disease in some cases. Therefore, early (pre-symptomatic) diagnosis and management may save lives. However, clinically false negative relatives are also at risk of sudden death. On this basis we conclude assessment of relatives should be extended with genetic testing.

Death, Sudden, Cardiac↗

PubMed2006

Optimization of capillary array electrophoresis single-strand conformation polymorphism analysis for routine molecular diagnostics.

Mutation screening is widely used for molecular diagnostics of inherited disorders. Furthermore, it is anticipated that the present and future identification of genetic risk factors for complex disorders will increase the need for high-throughput mutation screening technologies. Capillary array electrophoresis (CAE) SSCP analysis is a low-cost, automated method with a high throughput and high reproducibility. Thus, the method fulfills many of the demands to be met for application in routine molecular diagnostics. However, the need for performing the electrophoresis at three temperatures between 18 degrees C and 35 degrees C for achievement of high sensitivity is a disadvantage of the method. Using a panel of 185 mutant samples, we have analyzed the effect of sample purification, sample medium and separation matrix on the sensitivity of CAE-SSCP analysis to optimize the method for molecular diagnostic use. We observed different effects from sample purification and sample medium at different electrophoresis temperatures, probably reflecting the complex interplay between sequence composition, electrophoresis conditions and sensitivity in SSCP analysis. The effect on assay sensitivity from three different polymers was tested using a single electrophoresis temperature of 27 degrees C. The data suggest that a sensitivity of 98-99% can be obtained using a 10% long chain poly-N,N-dimethylacrylamide polymer.

Acrylamides↗

PubMed2005

NOD2/CARD15 gene polymorphisms in Crohn's disease: a genotype-phenotype analysis in Danish and Portuguese patients and controls.

BACKGROUND: A North-South gradient in Crohn's disease (CD) implying a higher incidence in northern Europe compared to southern Europe has been established. AIMS: To investigate whether there is a difference between Denmark and Portugal in the frequency of CARD15 mutations in CD patients compared to a healthy background population and to compare genotype-phenotype relations in the two countries. METHODS: 58 Danish patients and 29 Portuguese patients with CD were matched for age, sex and disease behaviour at time of diagnosis and compared with 200 healthy Danish and Portuguese controls. Phenotypes were recorded at year of diagnosis, 3 years after diagnosis and at end of follow-up. Patients were genotyped for Arg702Trp, Gly908Arg and Leu1007InsC. RESULTS: 22% of the Danish patients vs. 9% of Danish controls compared to 21% of the Portuguese patients vs. 16% had at least one mutation. Mutation rates in Danish patients were significantly different (p=0.02) compared with Danish controls, no difference (p=0.51) was found between Portuguese patients and controls. However, a possible relationship between CD and presence of genetic mutations was found when comparing the two countries (p=0.03) using the Mantel-Haenszel test. No difference in evolution of phenotypes and the CARD15 status in CD was found during follow-up between the two matched populations. Ileal disease correlated to high occurrence of CARD15. CONCLUSION: No North-South gradient regarding occurrence of CARD15 was revealed. Although a trend towards more mutations in the Portuguese controls was seen, a relationship between CD and CARD15 mutations was observed in both countries.

Adult↗

PubMed2005

Genetic and environmental factors in monozygotic twins with Crohn's disease and their first-degree relatives: a case report.

BACKGROUND/AIMS: Familial Crohn's disease has shown concordance concerning location and clinical type of the disease especially among monozygotic twins. Susceptibility to Crohn's disease is both based on genetic and environmental factors. We investigated polymorphisms of CARD15, TLR4, and OCTN, and environmental factors in a monozygotic twin pair with Crohn's disease and their first-degree relatives. METHODS: 22-year-old monozygotic female twins with ileocolonic Crohn's disease and their healthy brother and parents were examined. DNA samples from patients and relatives were genotyped for CARD15, TLR4,and OCTN polymorphisms. ASCA and p-ANCA analyses were performed. Additionally, patients and relatives filled out a questionnaire concerning multiple environmental factors. RESULTS: Both twins presented in the same year with identical Vienna Classification phenotypes: stenotic behavior (B2) and localization in terminal ileum and colon (L3). Both carried a CARD15 R702W variant, but had normal alleles in TLR4 and OCTN. They were smokers since the age of 15, used oral contraceptives and had undergone appendectomy. The healthy father and brother were CARD15 R702W positive, were non-smokers and had not undergone appendectomy. CONCLUSION: This case report is the first to describe complete concordance in CARD15 status, phenotypic appearance, and smoking, appendectomy and oral contraceptive use in a pair of monozygotic twins with CD.

Adult↗

PubMed2005

High-throughput single-strand conformation polymorphism analysis on a microfabricated capillary array electrophoresis device.

A high-density 384-lane microfabricated capillary array electrophoresis device is evaluated for high-throughput single-strand conformation polymorphism (SSCP) analysis. A delayed back bias direct electrokinetic injection scheme is used to provide better than 10-bp resolution with an 8.0-cm effective separation length. Separation of a HaeIII digest of PhiX174 yielded theoretical plate numbers of 4.0 x 10(6). Using 5% PDMA containing 10% glycerol and 15% urea, 21 single-nucleotide polymorphisms (SNPs) from HFE, MYL2, MYL3, and MYH7 genes associated with hereditary hemochromatosis (HHC) and hereditary hypertrophic cardiomyopathy (HCM) are discriminated at two running temperatures (25 degrees C and 40 degrees C), providing 100% sensitivity. The data in this study demonstrate that the 384-lane microCAE device provides the resolution and detection sensitivity required for SSCP analysis, showing its potential for ultrahigh-throughput mutation detection.

Cardiomyopathies↗

PubMed2005

One third of Danish hypertrophic cardiomyopathy patients with MYH7 mutations have mutations [corrected] in MYH7 rod region.

Familial hypertrophic cardiomyopathy (FHC) is, in most cases, a disease of the sarcomere, caused by a mutation in one of 10 known sarcomere disease genes. More than 266 mutations have been identified since 1989. The FHC disease gene first characterized MYH7, encodes the cardiac beta-myosin heavy chain, and contains more than 115 of these mutations. However, in most studies, only the region encoding the globular head and the hinge region of the mature cardiac beta-myosin heavy chain have been investigated. Furthermore, most studies carries out screening for mutations in the most prevalent disease genes, and discontinues screening when an apparent disease-associated mutation has been identified. The aim of the present study was to screen for mutations in the rod region of the MYH7 gene in all probands of the cohort, regardless of the known genetic status of the proband. Three disease-causing mutations were identified in the rod region in four probands using capillary electrophoresis single-strand conformation polymorphism as a screening method. All mutations were novel: N1327K, R1712W, and E1753K. Two of the probands had already been shown to carry other FHC-associated mutations. In conclusion, we show that in the Danish cohort we find one third of all MYH7 mutations in the rod-encoding region and we find that two of the patients carrying these mutations also carry mutations in other FHC disease genes stressing the need for a complete screening of all known disease genes in FHC-patients.

Amino Acid Substitution↗

PubMed2005

Disease concordance, zygosity, and NOD2/CARD15 status: follow-up of a population-based cohort of Danish twins with inflammatory bowel disease.

OBJECTIVES: A Danish cohort of twins with inflammatory bowel disease (IBD), Crohn's disease (CD) and ulcerative colitis (UC), has previously been collected. The aim of the present study was to reassess this cohort in order to compare clinical characteristics in concordant versus discordant twin pairs, test twin zygosity genetically, follow-up on disease concordance, and examine NOD2/CARD15 genetic status. METHODS: The Danish cohort is one of two population-based cohorts worldwide and consists of 103 twin pairs. After median 13 yr of follow-up, all twins were contacted and hospital files were scrutinized to reassess disease concordance and obtain phenotype data. DNA was obtained from 123 twins for analysis of zygosity and prevalence of the three common NOD2/CARD15 mutations. RESULTS: Zygosity tested genetically was consistent with the former assessment based on questionnaires. The proband concordance for CD remained fairly stable: 63.6% among monozygotic (MZ) twins and 3.6% among dizygotic (DZ) twins. Clinical characteristics were similar in twins from concordant versus discordant pairs. Forty-four percent of patients with CD were positive for >or=1 mutant allele of NOD2/CARD15 compared to 2% of UC patients (p < 0.001) and 19% of healthy twins (p= 0.02). The allele mutation frequency was 43% among the healthy twins to patients with CD versus 9% among twins to UC patients (p= 0.01). CONCLUSIONS: Previous questionnaire assessment of twin zygosity was confirmed by genetic test. Concordance for CD remained quite stable and was significantly higher among MZ than DZ twins. A high NOD2/CARD15 mutation frequency was observed both among CD twins and their healthy siblings.

Adult↗

PubMed2004

Does KCNE5 play a role in long QT syndrome?

BACKGROUND: Long QT syndrome [LQTS] is a congenital cardiac disease characterised by prolonged QTC-time, syncopes and sudden cardiac death. LQTS is caused by mutations in genes coding for ion channels involved in the action potential. KCNE5 codes for a novel beta-subunit of the ion channel conducting the delayed rectifier repolarizing current IKs. As KCNE5 is expressed in the human heart and suppresses the IKs current in heterologous systems, it is a candidate gene that may be mutated in LQTS families where no causative mutations in known LQTS associated genes have been found. We examined whether this was the case. METHODS: Genomic DNA from LQTS patients [n=88] and normal controls [n=90] was screened for mutations in KCNE5 by endonuclease-enhanced single strand conformation polymorphism analysis [EE-SSCP], and DNA sequencing of aberrant conformers. Mutations in other LQTS associated ion channels were excluded by SSCP. RESULTS: No mutations were found in the coding region of the KCNE5 gene in LQTS patients. One polymorphism, a T-to-C transition at nucleotide 97, causing an amino acid polymorphism P33S, was present in 16 persons, nine heterozygotes and seven homozygotes. The T-allele frequency was 0.13 in LQTS patients and 0.10 in controls.

Action Potentials↗

PubMed2003

High-throughput single strand conformation polymorphism mutation detection by automated capillary array electrophoresis: validation of the method.

Capillary array electrophoresis (CAE) is a novel technique, which allows for high throughput analysis of DNA fragments. When screening for mutations in whole populations or large patient groups it is necessary to have robust and well-characterized setups for high throughput analysis. For large-scale mutation screening, we have developed procedures for single strand conformation polymorphism (SSCP) assays using CAE (CAE-SSCP) whereby we may increase both the sensitivity and the throughput compared to conventional SSCP analysis. In this study we have validated CAE-SSCP by 1) comparing detection by slab-gel based SSCP with CAE-SSCP of mutations in the MYH7, MYL2, and MYL3 genes encoding sarcomere proteins from patients suffering from hypertrophic cardiomyopathy; and 2) by constructing a series of 185 mutants having substitution mutations, as well as insertion/deletion mutations, or some combinations of these, in different sequence contexts in four exons and different positions relative to the end of the amplicon (three from the KCNQ1 gene, encoding a cardiac potassium channel, and one from the TNNI3 gene encoding cardiac troponin I). The method identified 181 out of 185 mutations (98%), and the data suggest that the position of mutation in the fragment had no effect on the sensitivity. Analysis of the specificity of the method showed that only very few mutants could not be distinguished from each other and there were no false positives.

Automation↗

PubMed2003

Capillary electrophoresis-based single strand DNA conformation analysis in high-throughput mutation screening.

The generation of the draft human genome sequence has created new possibilities for diagnosis, prevention, and treatment of human disease. One consequence of these new possibilities is an increasing need for methods and technology that can be used for high-throughput screening for mutations in large DNA sample materials. In recent years, a number of mutation screening methods have emerged that are based on the analysis of sequence-dependent changes in the conformation of single- and double-stranded DNA using capillary electrophoresis. Common features of these methods are high sensitivity and reproducibility as well as the possibility for automation and massive parallelization. Thus, at present they are among the most attractive technologies for high-throughput mutation screening. This review describes the recent advances in capillary electrophoresis-based single strand conformation polymorphism (CE-SSCP) for detection of unknown mutations, and assesses its practical usability for high-throughput mutation screening based on the available literature. In addition, future prospects are outlined in light of the recent advances in microchip-based capillary electrophoresis.

DNA Mutational Analysis↗

PubMed2003

Outcome of clinical versus genetic family screening in hypertrophic cardiomyopathy with focus on cardiac beta-myosin gene mutations.

OBJECTIVE: Familial hypertrophic cardiomyopathy (FHC) is caused by mutations in genes encoding cardiac sarcomere proteins. Although available, genetic analyses are generally not used clinically. In the present study, we evaluated the outcome of clinical vs. genetic screening of family members with specific focus on mutations in the cardiac beta-myosin heavy chain (MYH7) gene. METHODS: A consecutive cohort of 68 FHC probands and their families (395 persons) of Danish origin was evaluated including patient- and family histories, physical examinations, electrocardiogram and echocardiography. Mutation screening was performed by a combination of single strand conformation/heteroduplex analysis and direct sequencing. RESULTS: Eight different MYH7 gene mutations were identified in nine (13%) families (96 persons). In eight (89%) of the families, major cardiac events had occurred. Myectomy or percutaneous septal alcohol ablation had been performed in a higher number of MYH7 probands i.e. in five of nine (56%) as compared to 10 of 59 (17%) (P<0.05) non-MYH7 mutation probands. Neither echocardiographic nor ECG findings were useful to distinguish MYH7 from non-MYH7 probands. Between adult MYH7 mutation-carriers (n=38) and their non-carrier relatives (n=39), low sensitivity and specificity of the clinical diagnostic criteria tested were observed and minor clinical diagnostic criteria alone were not useful for identification of mutation carriers. By genetic screening of relatives with no or only minor hypertrophy on echocardiography, i.e. a priori possible mutation-carriers normally recommended clinical follow-up-the diagnosis was excluded in 52 (83%) persons. In addition, six relatives with secondary hypertrophy were identified as non-carriers. CONCLUSION: Neither echocardiographic nor ECG findings were useful to distinguish MYH7 from non-MYH7 probands. Extension of screening to include genetic analyses offered a marked diagnostic advantage as compared to clinical screening alone in FHC families.

Adolescent↗