Genotyping data sets may contain errors that, in some instances, lead to false conclusions. Deviation from Hardy-Weinberg equilibrium (HWE) in random samples may be indicative of problematic assays. This study has analysed 107 000 genotypes generated by TaqMan, RFLP, sequencing or mass spectrometric methods from 443 single-nucleotide polymorphisms (SNPs). These SNPs are distributed both within genes and in intergenic regions. Genotype distributions for 36 out of 313 assays (11.5%) whose minor allele frequencies were 40.05 deviated from HWE (Po0.05). Some of the possible reasons for this deviation were explored: assays for five SNPs proved nonspecific, and genotyping errors were identified in 21 SNPs. For the remaining 10 SNPs, no reasons for deviation from HWE were identified. We demonstrate the successful identification of a proportion of nonspecific assays, and assays harbouring genotyping error. Consequently, our current high-throughput genotyping system incorporates tests for both assay specificity and deviation from HWE, to minimise the genotype error rate and therefore improve data quality.

WHAT IS ALREADY KNOWN ABOUT THIS SUBJECT• P2X7 receptors are involved in the production of pro-inflammatory cytokines, such as Il-1b, by central and peripheral immune cells. Il-1b has been implicated as an important mediator of inflammation. Therefore, the P2X7 receptor is an attractive therapeutic target for inflammatory diseases. WHAT THIS STUDY ADDS• Findings in pharmacokinetics, pharmacodynamics, safety and tolerability of a P2X7 receptor modulator, GSK1482160, from the first human study for the molecule are described. A pharmacokinetic/ pharmacodynamic model for LPS-stimulated ATP-induced Il-1b production in blood allowed the integration of all relevant data and provided in vivo evidence of the nature of the drug-receptor interaction. The model has the potential to be used to simulate future trials. AIMSThis paper describes findings from the first-in-human study for GSK1482160, an orally available allosteric P2X7 receptor modulator. The study aimed to assess the pharmacokinetics (PK), pharmacodynamics (PD), safety and tolerability of the compound in healthy subjects. METHODSEscalating single doses of up to 1 g were administered to healthy subjects in a single-blind and placebo-controlled fashion. Safety, tolerability, blood drug concentrations and ex vivo Il-1b production in blood were evaluated. RESULTSDrug concentration peaked within 3.5 h of dosing under fasting conditions and declined thereafter with a relatively short half-life of less than 4.5 h. Exposure was proportional to dose with between subject variability of less than 60%. A PK/PD model quantified Il-1b as a function of drug exposure. The model allowed simulation of in vivo pharmacology for various untested dose levels and regimens. Furthermore, the mechanistic model supported the hypothesis that the compound reduces the efficacy of ATP at the P2X7 receptor without affecting its affinity. No major safety or tolerability concerns were identified in this small study (n = 29), except for one case of asymptomatic accelerated idioventricular rhythm at the top dose. CONCLUSIONThe model-based approach maximized analysis power by integrating all biomarker data and revealed mechanistic insight into the pharmacology of P2X7 modulation by GSK1482160. Simulations by this model ultimately led to the discontinuation of the development of this compound. The therapeutic relevance of the P2X7 receptor remains to be tested in patients. The mechanistic-model-based approach can be applied widely to drug development.

The cytochrome p450 enzyme, CYP2D6, metabolises approximately 20% of marketed drugs. CYP2D6 multiple variants are associated with altered enzyme activities. Genotyping 1018 Caucasians for CYP2D6 polymorphisms (G1846A, delT1707, delA2549 and A2935C), known to result in the recessive CYP2D6 poor drug metaboliser (PM) phenotype, identified 41 individuals with predicted PM phenotype. These 41 individuals were classified as 'cases'. Single nucleotide polymorphisms (SNPs) mapping within an 880 kb region flanking CYP2D6, were identified to evaluate potential association between genetic variation and the CYP2D6 PM phenotype. The 41 PM cases and 977 controls were genotyped and analysed for 27 SNPs. Associations were observed across a 390 kb region between 14 SNPs and the PM phenotype (P values from 6.20 ϫ 10 Ϫ4 to 4.54 ϫ 10 Ϫ35 ). Haplotype analysis revealed more significant levels of association (P ϭ 3.54 ϫ 10 Ϫ56 ). Strong (DЈ Ͼ 0.7) linkage disequilibrium (LD) between SNPs was observed across the same 390 kb region associated with the CYP2D6 phenotype. The observed phenotype:genotype association reached genome-wide levels of significance, and supports the strategy for potential application of LD mapping and whole genome association scans to pharmacogenetic studies.

Migraine is one of the most common diseases in the Western world, affecting approximately 14% of the adult population. Migraine can be subdivided into migraine with aura (MA) and without aura (MO), with 10% of migraineurs suffering exclusively from MA, and up to 20% having both types of attack. The term "typical migraine" describes migraine with or without aura, without additional syndromic traits such as hemiplegia. It is estimated that at least 18% of women and 6% of men suffer from migraine. Variation in migraine prevalence has been reported by ethnicity [1]. In women, migraine prevalence was significantly higher in Caucasians (20.4%) than in African (16.2%) or Asian (9.2%) Americans. A similar pattern was found among men (8.6%, 7.2%, and 4.2%