The bleeding risk during warfarin therapy is associated with the number of variant alleles of CYP2C9 and VKORC1 genes.

BACKGROUND: Warfarin is commonly used for the treatment and prevention of arterial and venous thromboembolism but its use is hindered by the risk of bleeding. The main reason for this risk is a narrow therapeutic index and a wide response variability after warfarin treatment. These shortcomings affect clinical outcomes including bleeding complications and may be associated with variant polymorphisms in the CYP2C9 and VKORC1 genes. AIM: It was the aim of this study to assess the impact of the total variant allele count of CYP2C9 and VKORC1 genes on bleeding related to warfarin treatment. METHODS: In a retrospective cohort-design study, patients were genotyped for polymorphisms in genes CYP2C9 (*1, *2, *3) and VKORC1 (haplotype A, B). Extensive clinical data were obtained. Adjusted hazard ratios (HR) for the occurrence of major bleeding events (MBE) were counted separately for the induction and maintenance phases of warfarin therapy. RESULTS: Out of the 329 patients in our clinical database, 194 patients were eligible and included in the analysis. MBE occurred in 51 patients (26.3%) during a mean follow-up of 26 months: 6 patients (11.8%) experienced early MBE during warfarin initiation, and 45 MBE occurred during the maintenance phase. The adjusted HR for MBE risk for patients with any CYP2C9 variant allele was 1.962 [95% confidence interval (CI) 1.08-3.56, p = 0.027]; for the VKORC1 AA haplotype, HR was 1.841 (95% CI 0.97-3.48, p = 0.06), while for 3 variant allele carriers of both genes, HR was 4.34 (95% CI 1.95-9.65, p < 0.001). Despite the insignificant association of the VKORC1 genotype with bleeding in our study, we have noted a warfarin dose-dependent effect with risk significance ascending: CYP2C9 *1/*1 + VKORC1 B/B < CYP2C9 *1/*1 + VKORC1 A/B < CYP2C9 *1/*2 + VKORC1 B/B. CONCLUSION: Patients who are carriers of 3 variant alleles of the genes CYP2C9 and VKORC1 exhibited a significantly higher risk of MBE during the initiation and maintenance phases of warfarin therapy. Vigilant and careful management of patients with a higher variant allele count, including switching to newer anticoagulants, could be considered in this high-risk cohort.

OmniPlex--a new QF-PCR assay for prenatal diagnosis of common aneuploidies based on evaluation of the heterozygosity of short tandem repeat loci in the Czech population.

OBJECTIVES: The aim of our study was to assess the utility of commonly used multiplex assays of short tandem repeat markers used for quantitative fluorescent polymerase chain reaction (QF-PCR) for prenatal rapid aneuploidy detection (RAD) in routine prenatal diagnosis in the Czech population. METHODS: Two previously published RAD multiplexes (2M test) were tested on 2906 local prenatal samples and used to calculate the rates of heterozygosity within this population. Most of the markers used in both multiplexes were highly informative. However, some had little utility, either due to a low heterozygosity rate (D21S499, D18S978 and P39) or because they were difficult to evaluate (DXS1283E). RESULTS: After evaluation of the 2M test results, a new multiplex assay (OmniPlex) was designed, developed and tested on 960 samples. This new assay was evaluated for heterozygosity rates and for the probability of having two or more informative markers on each chromosome. CONCLUSIONS: OmniPlex assay significantly improved the QF-PCR methodology for rapid prenatal aneuploidy detection in the Czech population. Based on detected heterozygosity of markers used for QF-PCR in this population, OmniPlex is a robust assay for the detection of chromosomes 13, 18, 21, X and Y in a single reaction.

QF-PCR-based prenatal detection of common aneuploidies in the Czech population: five years of experience.

We present the results from the largest clinical application of QF-PCR for antenatal rapid aneuploidy detection (RAD) in routine prenatal diagnosis in the Czech Republic. QF-PCR was performed in addition to karyotyping (dual testing) in two settings: the first was a single multiplex reaction testing only trisomy 21 and amelogenin X/Y alleles in the second trimester screened positive cases (T21 test), and the second setting consisted of two multiplexes (2M test) for common aneuploidies (13, 18, 21, X and Y) in cases with other RAD indications such as ultrasound findings, late booking or maternal anxiety. Dual testing was performed in 6349/12,778 (49.7%) of prenatal samples using either T21 or 2M test between 2002 and 2007. The clinical acceptability of our dual testing policy, methodological efficiency of RAD and residual risks of other chromosomal aberrations (CHAs) were evaluated. QF-PCR detected 92% (175/190) of significant CHAs. The 2M test identified 93.5% and the T21 test identified 87.5% of the significant CHAs with complete specificity. The residual risk of significant CHA was 1/231 in the 2M test and 1/565 in the T21 test. If RAD for all common aneuploidies is used as the sole prenatal diagnosis method, the odds of missing a CHA of any type are 1:90 and the odds of missing significant CHA with no ultrasound findings are 1:1513. If prenatal karyotyping were used as an additional procedure to RAD in cases only with ultrasound findings, 186/190 (97.8%) of the significant CHAs would be detected when 15.7% cases were karyotyped, according to our data. We consider RAD directed towards trisomy 21 alone (our T21 test) as an economically and clinically acceptable part of second trimester screening for Down syndrome. Both RAD tests allow fast alleviation of maternal anxiety with low residual risk when the test results are negative, and allow fast decision making if the results are positive. However, replacement of dual testing with only the RAD procedure in specific indications accepted in some countries (Great Britain) remains in the Czech Republic a theme for debate.

Polymorphisms and low plasma activity of dopamine-beta-hydroxylase in ADHD children.

Attention-deficit Hyperactivity disorder (ADHD) is a multifactorial disorder clinically characterized by inattentiveness, impulsivity and hyperactivity. The occurrence of this disorder is between 3 and 6% of the children population, with boys predominating over girls at a ratio of 3:1 or more. The research of some candidate genes (DRD4, DAT, DRD5, DBH, 5HTT, HTR1B and SNAP25) brought consistent results confirming the heredity of ADHD syndromes. Dopamine-beta-hydroxylase (DBH) is an enzyme responsible for the conversion of dopamine into noradrenaline. Alteration of the dopamine/noradrenaline levels can result in hyperactivity. The DBH protein is released in response to stimulation. DBH activity, derived largely from sympathetic nerves, can be measured in human plasma. Patients with ADHD showed decreased activities of DBH in serum and urine. Low DBH levels correlate indirectly with the seriousness of the hyperkinetic syndrome in children [19,20]. In the DBH gene, the G444A, G910T, C1603T, C1912T, C-1021T, 5 -ins/del and TaqI polymorphisms occur frequently and may affect the function of gene products or modify gene expression and thus influence the progression of ADHD. This article reviews the DBH itself and polymorphisms in the DBH gene that influence the DBH activity in the serum and the CSF level of DBH. All those are evaluated in connection with ADHD.

Genotype/phenotype correlation in a SCA1 family: anticipation without CAG expansion.

We report on a family with spinocerebellar ataxia type 1 (SCA1), in which the age at onset and the severity of the disease do not correlate with the number of CAG repeat units. Although a marked anticipation was observed in the proband, it was not a consequence of an expansion of the CAG tract. None of the expanded alleles contained CAT interruptions. The pathologic expansion in this family was stable during the paternal but not maternal transmission, where it expanded by one trinucleotide and unexpectedly did not lead to anticipation. Our observations suggest that factors other than the length of the CAG repeat play a considerable role in determination of the disease course.

DiGeorge/velocardiofacial syndrome: FISH studies of chromosomes 22q11 and 10p14, and clinical reports on the proximal 22q11 deletion.

DiGeorge anomaly/velocardiofacial syndrome (DG/VCFS) occurs with different deletion intervals on chromosomes 22q11, while the DiGeorge anomaly (with other findings) is seen in patients with deletions of 10p14. The clinical outcome with the common 22q11 deletion (90% of cases) is well known, but the outcome with the less frequent deletion types has not been well documented. Using cytogenetic and fluorescence in situ hybridization (FISH) analysis we studied a series of 295 patients with suspected DG/VCFS. We identified 58 subjects with a 22q11 deletion, and none with a 10p deletion. Fifty-two subjects had the common deletion, five had the proximal deletion, and one had an atypical proximal deletion due to a 1;22 translocation. We report clinical data of four subjects with the proximal 22q11 microdeletion, and of one patient with the atypical proximal deletion. The anomalies observed with the proximal 22q11 microdeletion fell within the DG/VCFS spectrum. Two females, 6 and 25 years old, had normal mental development. Normal development has been reported with the common 22q11 deletion, but only in a minority of cases. This study may indicate a better intellectual and/or behavioral outcome with the proximal vs. the common 22q11 deletion, rather than a chance finding.

Is there anticipation in the age at onset of cancer in families with Li-Fraumeni syndrome?

Anticipation in the age at onset of cancer in successive generations was described in several familial cancer syndromes. Based on multiple statistical analyses of a database of families with germline TP53 mutations, and using several different approaches and measures to eliminate possible biases, we show that anticipation may be a feature of the Li-Fraumeni syndrome. Definitive proof of anticipation in pedigrees with germline TP53 mutations will require more family data and further analysis, as well as research on the role of the p53 protein in processes like genome stability, which may represent the biological basis of anticipation in these families. This should have important practical implications for genetic testing, counselling, and preventative care for individuals at risk.