TERWILLIGER [177] has described a class of powerful likelihood-based methods for detecting association between one or more polymorphic markers and a disease trait. These tests can be applied equally efficiently to di-allelic polymorphisms such as the tested β2 adrenoceptor genotypes. Based on an type 1 error (P-value) of 0.001 and with 347 hypertensives from the upper quintile and 284 control subjects from the lower quintile of the blood pressure distribution the study has a power of 95% to detect a doubling of the risk (odds ratio of 2.0) of hypertension associated with the variants of the β2 adrenergic receptor gene.
We have deliberately selected a stringent significance level (P = 0.001) for our power calculations as we were determined to take full advantage of the unique opportunity provided by the Caerphilly cohort to investigate the genetic basis of blood pressure variability in the population.
© 2001 Alexander Binder