Despite the success of recent genome-wide association studies (GWAS) investigating longitudinal traits, a large fraction of overall heritability remains unexplained. This suggests that some of the missing heritability may be accounted for by gene-gene and gene-time/environment interactions. In this paper, we develop a Bayesian variable selection method for longitudinal genetic data based on mixed models. The method jointly models the main effects and interactions of all candidate genetic variants and non-genetic factors and has higher statistical power than previous approaches. To account for the within-subject dependence structure, we propose a grid-based approach that models only one fixed-dimensional covariance matrix, which is thus applicable to data where subjects have different numbers of time points. We provide the theoretical basis of our Bayesian method and then illustrate its performance using data from the 1000 Genome Project with various simulation settings. Several simulation studies show that our multivariate method increases the statistical power compared to the corresponding univariate method and can detect gene-time/environment interactions well. We further evaluate our method with different numbers of individuals, variants, and causal variants, as well as different trait-heritability, and conclude that our method performs reasonably well with various simulation settings.

Propofol is a rapidly acting intravenous anesthetic agent used for the induction of anesthesia, with a low incidence of side effects. But pain on injection of propofol has limited its use. The additional effect of lidocaine on painful injection of propofol was studied, during induction of general anesthesia in 75 patients in a prospective, randomized method. They were allocated randomly to three groups to receive propofol 2.0 mg/kg(group A), propofol 2.0 mg/kg with lidocaine 0.2 mg/kg(group B), propofol 2.0 mg/kg with lidocaine 0.3 mg/kg(group C). Pain score was assessed on a simple scale graded from 0 (no pain) to 3 (severe pain). Mean arterial blood pressure and heart rate were monitored at 1, 3, 5, 7 minutes after endotracheal intubation. In group B and C, significantly smaller pain score was observed. On the other hand, changes of mean arterial blood pressure and heart rate after endotracheal intubation was not significant. It is concluded that the addition of small amount of lidocaine can significantly reduce the severity of pain on injection of propofol.
Anesthesia ; Anesthesia, General ; Arterial Pressure ; Hand ; Heart Rate ; Humans ; Incidence ; Injections, Intravenous ; Intubation, Intratracheal ; Lidocaine* ; Propofol ; Prospective Studies