Genome-wide association study for white coat effect in Japanese middle-aged to elderly people: The HOMED-BP study

Background: White coat effect (WCE), the blood pressure (BP) difference between clinical and non-clinical settings, can lead to clinical problems such as misdiagnosis of hypertension. Etiology of WCE has been still unclear, especially from genetic aspects. The present article investigated association between genome-wide single nucleotide polymorphisms (SNPs) and WCE in patients with essential hypertension.Methods: The present cross-sectional analyses were based on 295 Japanese essential hypertensive outpatients aged 40years enrolled in randomized control study, Hypertension Objective Treatment Based on Measurement by Electrical Devices of Blood Pressure (HOMED-BP) study, who were not taking antihypertensive medications before the randomization. Home and clinic BP were measured. WCE was defined by subtracting home BP from clinic BP. Genotyping was conducted with 500K DNA microarray chips. Association between genome-wide SNPs and WCE were analyzed. For replication (p<10(-4)), we analyzed participants from Ohasama study who took no antihypertension medications and whose SNPs were collected.Results: Genome-wide SNPs were not significantly associated with WCE of systolic and diastolic BP after corrections of multiple comparisons (p<2x10(-7)). We found suggestive SNPs associated with WCE of systolic and diastolic BP (p<10(-4)). However, the consistent results were not obtained in the replication study.Conclusion: The present article showed no significant association between genome-wide SNPs and WCE. Since there were several suggestive SNPs associated with WCE, the present study warrants a further study with bigger sample size for investigating the genetic influence on WCE.