Pharmaceutical Outcomes Programme, Children's and Women's Health Centre of British Columbia, Child and Family Research Institute, University of British Columbia, Vancouver, British Columbia, Canada. bcarleton@popi.ubc.ca
Adverse drug reactions (ADRs) rank as the fifth leading cause of death in the western world. The nature and scope of these ADRs in children are not predictable based on post market surveillance reports that rely heavily on adult drug experience. The genotype-specific approaches to therapy in childhood (GATC) national ADR network was established to identify specific ADRs and to improve drug safety through identification of predictive genomic biomarkers of drug risk.
GATC set out to establish a national network of trained surveillance clinicians in pediatric hospitals across Canada. Surveillance clinicians identified, enrolled, and collected clinical data and biological samples from ADR cases and controls. Surveillance was targeted to three ADRs: anthracycline-induced cardiotoxicity, cisplatin-induced hearing impairment, and codeine-induced mortality in breastfed infants.
The initial surveillance site was established in September 2005, with 10 sites fully operational by 2008. In 3 years, GATC enrolled 1836 ADR cases and 13188 controls. Target numbers were achieved for anthracycline-induced cardiotoxicity. Modified target numbers were nearly attained for cisplatin-induced hearing impairment. Codeine-induced infant mortality in a breastfed infant was discovered by GATC investigators. A case-control study was subsequently conducted.
GATC has demonstrated a model of active and targeted surveillance that builds an important step toward the goal of personalized medicine for children. Effective communication, site-specific solutions and long-term sustainability across the network are critical to maintain participation and productivity. GATC may provide a framework of ADR surveillance that can be adapted by other countries and healthcare systems.
Eskimos and to a slightly lesser degree Northern Indians are extremely rapid acetylators as tested with isoniazid. They also tend to clear phenytoin rapidly as proven in Greenland Eskimos and supported by clinical observations in Canadian Eskimos. Most "silent gene" cholinesterase cases found in Canada came from the tiny minorities of Northern Indians and Eskimos and an even higher prevalence was found in an isolate of South Western Alaskan Eskimos. We found alcohol metabolism significantly slower in Northern Indians and Eskimos than Caucasians, which is at variance with findings in other Amerindian groups and Asiatic Mongoloids reflecting perhaps quite different physical and nutritional environments over long periods of time. Pecularities of sugar metabolism found in Natives of the Canadian Arctic and Sub-Arctic may also be best explained by the relative deficiency of carbohydrates in their traditional diet.
Notes
From: Fortuine, Robert et al. 1993. The Health of the Inuit of North America: A Bibliography from the Earliest Times through 1990. University of Alaska Anchorage. Citation number 2243.
Androgen receptor gene CAG repeat length as a modifier of the association between persistent organohalogen pollutant exposure markers and semen characteristics.
Molecular Reproductive Medicine Research Unit, Department of Clinical Sciences, Reproductive Medicine Centre, Malmö University Hospital, Lund University, Malmö, Sweden. aleksander.giwercman@med.lu.se
OBJECTIVES: Exposure to persistent organohalogen pollutants was suggested to impair male reproductive function. A gene-environment interaction has been proposed. No genes modifying the effect of persistent organohalogen pollutants on reproductive organs have yet been identified. We aimed to investigate whether the CAG and GGN polymorphisms in the androgen receptor gene modify the effect of persistent organohalogen pollutant exposure on human sperm characteristics. METHODS: Semen and blood from 680 men [mean (SD) age 34 (10) years] from Greenland, Sweden, Warsaw (Poland) and Kharkiv (Ukraine) were collected. Persistent organohalogen pollutant exposure was assessed by measuring serum levels of 2,2',4,4',5,5'-hexachlorobiphenyl (CB-153) and dichlorodiphenyl dichloroethene (p,p'-DDE). Semen characteristics (volume, sperm concentration, total count, proportion of progressively motile and morphology) and DNA fragmentation index (DFI) were determined. CAG and GGN repeat lengths were determined by direct sequencing of leukocyte DNA. RESULTS: A statistically significant interaction was found between the CB-153 group and CAG repeat category in relation to sperm concentration and total sperm count (P=0.03 and 0.01, respectively). For p,p'-DDE, in the European cohorts a significant interaction was found in relation to DFI (P=0.01). For CAG
OBJECTIVES: The renin-angiotensin system may play a role in the pathogenesis of atrial fibrillation, and renin-angiotensin system blockers reduce the risk of atrial fibrillation. We hypothesized that polymorphisms in the angiotensinogen and angiotensin-converting enzyme (ACE) genes encoding proteins in this system predict risk of atrial fibrillation. METHODS AND RESULTS: We genotyped 9235 individuals from the Danish general population, The Copenhagen City Heart Study, for the a-20c, g-6a, T174M, and M235T polymorphisms in the angiotensinogen gene and the insertion/deletion (I/D) polymorphism in the ACE gene; rare allele frequencies were 0.16, 0.40, 0.12, 0.41, and 0.49, respectively. Participants had sinus rhythm at inclusion. During 26 years of follow-up, 968 individuals developed atrial fibrillation. Multifactorially adjusted hazard ratios for atrial fibrillation for a-20c ac and cc versus aa genotype were 1.1(95% confidence interval: 1.0-1.3; P=0.05) and 1.5(1.1-2.1; P=0.01). Compared with double noncarriers (angiotensinogen -20aa and ACE II), double heterozygotes (ac-I/D genotype), and double homozygotes (cc-DD) had hazard ratios for atrial fibrillation of 1.2(0.9-1.6; P=0.06) and 2.4(1.4-4.1; P=0.001). a-20c cc homozygotes above 70 years of age who were overweight, severely hypertensive, and had heart failure, had an absolute 10-year risk of atrial fibrillation of 61%. CONCLUSION: Angiotensinogen a-20c genotype alone and in combination with ACE I/D genotype predicts an increased risk of atrial fibrillation. Therefore, genetic variation in the renin-angiotensin system may influence effect of renin-angiotensin system blockers on atrial fibrillation.
Centre for Molecular Medicine and Therapeutics, Child and Family Research Institute, Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia, Canada.
Ethnicity can confound results in pharmacogenomic studies. Allele frequencies of loci that influence drug metabolism can vary substantially between different ethnicities and underlying ancestral genetic differences can lead to spurious findings in pharmacogenomic association studies. We evaluated the application of principal component analysis (PCA) in a pharmacogenomic study in Canada to detect and correct for genetic ancestry differences using genotype data from 2094 loci in 220 key drug biotransformation genes. Using 89 Coriell worldwide reference samples, we observed a strong correlation between principal component values and geographic origin. We further applied PCA to accurately infer the genetic ancestry in our ethnically diverse Canadian cohort of 524 patients from the GATC study of severe adverse drug reactions. We show that PCA can be successfully applied in pharmacogenomic studies using a limited set of markers to detect underlying differences in genetic ancestry thereby maximizing power and minimizing false-positive findings.
The activity of the enzymes that metabolize tobacco smoke may affect the susceptibility to chronic obstructive pulmonary disease (COPD). Cytochrome P450 (CYP) 3A5 is expressed selectively over CYP3A4 in human lung, but the association between the CYP3A5 polymorphisms and the airway injury is unknown.
Two hundred and six male Saskatchewan grain workers participated in this longitudinal study, and their lung function values of forced expiratory volume in the first second (FEV1) and forced vital capacity (FVC), respiratory symptoms, smoking status, and the occupational history were analyzed.
A significant interactive effect was observed between the CYP3A5 genotype and current smoking status on FEV1, and the annual decline rates of FEV1 and FVC in current smokers were greater among CYP3A5*1/*3 carriers than CYP3A5*3/*3 carriers (-48.7+/-16.4 vs. -31.5+/-4.7 ml/years, P=0.02; -27.4+/-18.9 vs. -5.8+/-6.5 ml/years, P=0.04). The incidences of chronic cough and COPD were also higher in current smokers with CYP3A5*1/*3 than in nonsmokers and current smokers with CYP3A5*3/*3. The adjusted odds ratios for chronic cough and COPD current smokers with CYP3A5*1/*3 versus nonsmokers with the CYP3A5*3/*3 genotype were 11.4 (P=0.009) and 4.3 (P=0.13), respectively.
The results suggest that CYP3A5*1 may be a novel genetic risk factor for airway injury in smokers, and that CYP3A5 may play a role in airway injury owing to the bioactivation of chemicals in tobacco smoke.
*Department of Geriatric Medicine, Oslo University Hospital; †Department of Pharmaceutical Services, The Hospital Pharmacies; ‡Institute of Clinical Medicine, University of Oslo; §Department of Pharmaceutical Bioscience, School of Pharmacy, University of Oslo; and ¶Center for Psychopharmacology, Diakonhjemmet Hospital, Oslo, Norway.
To compare measures of anticholinergic activity between metabolic phenotypes of the polymorphic enzymes cytochrome P450 2D6 (CYP2D6) and CYP2C19 in the elderly patients exposed to anticholinergic agents.
Long-term nursing home patients (n = 80) with an anticholinergic drug scale (ADS) score =3 were recruited from 22 nursing homes in Norway. Based on pharmacogenetic analyses of mutations encoding absent CYP2D6 or CYP2C19 metabolism, patients were divided into subgroups of poor metabolizers (PMs) (n = 8) and extensive metabolizers (n = 72). Serum anticholinergic activity (SAA) was determined by a validated, 96-well format radio receptor assay and adjusted for ADS score. Unadjusted and adjusted SAAs, mouth dryness, and cognitive function (Mini-Mental State Examination and verbal recall tests from Consortium to Establish a Registry for Alzheimer Disease) were compared between the subgroups with Mann-Whitney tests.
The study population was represented by 78% women, 68% had mild to moderate dementia, and mean age was 86 years. More than 80% used more than 1 anticholinergic agent, and their median ADS score was 4. The subpopulation of PMs had significantly higher median SAA than the extensive metabolizers (10.3 versus 4.2 pmol atropine equivalents per milliliter, P = 0.012). This difference remained significant after adjusting for ADS score (P = 0.013). No significant differences in mouth dryness and cognitive function were observed between the subgroups (P > 0.3).
These preliminary findings suggest that elderly CYP2D6/CYP2C19 PMs with a high anticholinergic drug burden are at increased risk of elevated SAA. Whether PMs are also more prone to experience anticholinergic side effects needs to be further studied in larger patient populations.
[Association of ITGB3, P2RY12, and CYP2C19 gene polymorphisms with platelet functional activity in patients with coronary heart disease during dual antiplatelet therapy].
To assess the association of CYP2C19 G681A, P2RY12 H1/H2, and ITGB3 T1565C polymorphisms with the extent of platelet aggregation in patients with coronary heart disease (CHD) during antiplatelet therapy.
166 male patients with CHD, living in the Western Siberian Region, were examined. All the patients underwent a test for platelet aggregation induced by ADP (2.5 and 5.0 µm) and epinephrine (0.2 µm). Genotyping was performed using an allele-specific polymerase chain reaction technique.
The polymorphic variants of the P2RY12 and ITGB3 genes were ascertained to have no impact on the extent of platelet aggregation in patients receiving clopidogrel and acetylsalicylic acid. An association was found between CYP2C19 681A allele carriage and the increased extent of platelet aggregation induced by ADP.
The carriage of the cytochrome P450 CYP2C19 681A allele rather than platelet receptor gene polymorphisms determines a risk for clopidogrel resistance in patients with CHD.
Department of Medical Genetics, Faculty of Medicine, Centre for Molecular Medicine and Therapeutics, University of British Columbia, Vancouver, Canada.
Adverse drug reactions (ADRs) rank as one of the top 10 leading causes of death in the developed world, and the direct medical costs of ADRs exceed $100 billion annually in the United States alone. Pharmacogenomics research seeks to identify genetic factors that are responsible for individual differences in drug efficacy and susceptibility to ADRs. This has led to several genetic tests that are currently being used to provide clinical recommendations. The Canadian Pharmacogenomics Network for Drug Safety is a nation-wide effort established in Canada to identify novel predictive genomic markers of severe ADRs in children and adults. A surveillance network has been established in 17 of Canada's major hospitals to identify patients experiencing specific ADRs and to collect biological samples and relevant clinical history for genetic association studies. To identify ADR-associated genetic markers that could be incorporated into predictive tests that will reduce the occurrence of serious ADRs, high-throughput genomic analyses are conducted with samples from patients that have suffered serious ADRs and matched control patients.
ADRs represent a significant unmet medical problem with significant morbidity and mortality, and Canadian Pharmacogenomics Network for Drug Safety is a nation-wide network in Canada that seeks to identify genetic factors responsible for interindividual differences in susceptibility to serious ADRs.
Active ADR surveillance is necessary to identify and recruit patients who suffer from serious ADRs. National and international collaborations are required to recruit sufficient patients for these studies. Several pharmacogenomics tests are currently in clinical use to provide dosing recommendations, and the number of pharmacogenomics tests is expected to significantly increase in the future.
