Gender, ethnicity and genetics in cardiovascular disease: part 1: Basic principles

Community-led risk analysis of direct-to-consumer whole-genome sequencing

Direct-to-consumer (DTC) genetic testing is cheaper and more accessible than ever before; however, the intention to combine, reuse, and resell this genetic information as powerful data sets is generally hidden from the consumer. This financial gain is creating a competitive DTC market, reducing the price of whole-genome sequencing (WGS) to under 300 USD. Entering this transition from single-nucleotide polymorphism-based DTC testing to WGS DTC testing, individuals looking for access to their whole-genomic information face new privacy and security risks. Differences between WGS and other methods of consumer genetic tests are left unexplored by regulation, leading to the application of legal data anonymization methods on whole-genome data, and questionable consent methods. Large representative genomic data sets are important for research and improve the standard of medicine and personalized care. However, these data can also be used by market players, law enforcement, and governments for surveillance, population analyses, marketing purposes, and discrimination. Here, we present a summary of the state of WGS DTC genetic testing and its current regulation, through a community-based lens to expose dual-use risks in consumer-facing biotechnologies.

The Recruitment Innovation Center: Developing novel, person-centered strategies for clinical trial recruitment and retention

Clinical trials continue to face significant challenges in participant recruitment and retention. The Recruitment Innovation Center (RIC), part of the Trial Innovation Network (TIN), has been funded by the National Center for Advancing Translational Sciences of the National Institutes of Health to develop innovative strategies and technologies to enhance participant engagement in all stages of multicenter clinical trials. In collaboration with investigator teams and liaisons at Clinical and Translational Science Award institutions, the RIC is charged with the mission to design, field-test, and refine novel resources in the context of individual clinical trials. These innovations are disseminated via newsletters, publications, a virtual toolbox on the TIN website, and RIC-hosted collaboration webinars. The RIC has designed, implemented, and promised customized recruitment support for 173 studies across many diverse disease areas. This support has incorporated site feasibility assessments, community input sessions, recruitment materials recommendations, social media campaigns, and an array of study-specific suggestions. The RIC’s goal is to evaluate the efficacy of these resources and provide access to all investigating teams, so that more trials can be completed on time, within budget, with diverse participation, and with enough accrual to power statistical analyses and make substantive contributions to the advancement of healthcare.

Cardiovascular Disease: An Introduction

Cardiovascular disease (CVD) is a collective term designating all types of affliction affecting the blood circulatory system, including the heart and vasculature, which, respectively, displaces and conveys the blood.

Dialogues on diversifying clinical trials: successful strategies for engaging women and minorities in clinical trials

There is mounting scientific evidence pointing to genetic or physiologic distinctions between genders and among racial and ethnic groups that influence disease risk and severity and response to treatment. The diverse enrollment of subjects engaged in clinical trials research is, thus, critical to developing safer and more effective drugs and medical devices. However, in the United States, there are striking disparities in clinical trial participation. To address this problem, the Food and Drug Administration (FDA) Office of Women's Health and the Society for Women's Health Research (SWHR) together convened the 2-day meeting, Dialogues on Diversifying Clinical Trials. The conference was held in Washington, DC, on September 22-23, 2011, and brought together a wide range of speakers from clinical research, industry, and regulatory agencies. Here, we present the major findings discussed at this meeting about female and minority patients and physicians and their willingness to participate in clinical trials and the barriers that sponsors face in recruiting a diverse trial population. We also discuss some recommendations for improving trial diversity through new technologies and greater efficiency in trial regulation and review.

Circadian variation of acute st segment elevation myocardial infarction by anatomic location in a Turkish cohort

Background

To evaluate the relationship between site of infarction (anterior vs. inferior) and circadian variation in patients with ST segment elevation myocardial infarction (STEMI) in a Turkish cohort.

Material/Methods

This restrospective study enrolled 465 patients (407 male, mean age 65±7 years) with STEMI. Patients were then categorised into 4 6-hour increments according to the time of day during which the symptoms began (12:00 AM–06:00 AM, 06:00 AM–12:00 PM; 12:00 PM–06:00 PM and 06:00 PM–12:00 AM hours). Characteristics of patients by site of infarction (anterior vs. inferior) were compared.

Results

The frequency of onset of acute anterior MI as determined by onset of pain demonstrated significant circadian variation among the 4 time periods, demonstrating bimodal peaks (afternoon and morning) and a trough between 06:00 PM to 06:00 AM. The incidence of occurrence of MI between 06:00 AM to 06:00 PM was 4.50 times that of the average frequency of the remaining 12 hours of the day. The frequency of onset of acute inferior MI as determined by onset of pain exhibited significant circadian variation among the 4 time periods, demonstrating bimodal peaks (midnight to 06:00 AM and 06:00 AM to noon) and a trough between noon to midnight. The incidence of occurrence of MI between midnight to noon was 4.25 times that of the average frequency of the remaining 12 hours of the day.

Conclusions

Different circadian periodicity in the time of onset of STEMI was found regarding infarction site in a Turkish cohort. This may be related to genetic and/or demographic characteristics of the Turkish population.

The Isfahan cohort study: rationale, methods and main findings

A 10-year longitudinal population-based study, entitled the Isfahan Cohort Study (ICS) is being conducted. The ICS commenced in 2001, recruiting individuals aged 35+ living in urban and rural areas of three counties in central Iran, to determine the individual and combined impact of various risk factors on the incidence of cardiovascular events. After 24379 person-years of follow-up with a median follow-up of 4.8 years, we documented 219 incident cases of ischemic heart disease (IHD) (125 in men and 94 in women) and 57 incident cases of stroke (28 in men and 29 in women). The absolute risk of IHD was 8.9 (7.8-10.2) per 1000 person-years for all participants, 10.6 (8.8-12.5) per 1000 person-years for men and 7.4 (6.0-9.0) per 1000 person-years for women. The respective risk of ischemic stroke was 2.3 (1.7-3.0), 2.3 (1.6-3.3) and 2.3 (1.5-3.2) per 1000 person-years. The risk of IHD was approximately 3.5-fold higher in the presence of hypertension, followed by diabetes mellitus and hypercholesterolemia with near 2.5- and twofold higher risk, respectively. This cohort provides confirmatory evidence of the ethnic differences in the magnitude of the impact of various risk factors on cardiovascular events. The differences may be due to varying absolute risk levels among populations and the existing ethnic disparities for using western risk equations to local requirements.

Triggers and the onset of acute myocardial infarction

The onset of acute myocardial infarction (AMI) is a complex interplay of internal circadian factors and external physical and emotional triggers. These interactions may lead to rupture of an often nonocclusive vulnerable atherosclerotic coronary plaque with subsequent formation of an occlusive thrombus. The onset of AMI has a distinct pattern, with peak incidence within the first few hours after awakening, on certain days of the week, and in the winter months. Physical and emotional stresses are important triggers of acute cardiovascular events including AMI. Triggering events, internal changes, and external factors vary among different geographical, environmental, and ethnic regions. Life-style changes, pharmacotherapy, and psychologic interventions may potentially modify the response to, and protect against the effects of triggering events.

Analysis of circadian variation of acute myocardial infarction: afternoon predominance in Turkish population

BACKGROUND

Although data about circadian variation of myocardial infarction (MI) in western populations reveal morning peak between 06:00 and 12:00 hours, differences have been reported in different regions of the world and ethnic groups. We aimed to evaluate circadian variation of MI in a Turkish cohort.

METHODS

A total of 476 patients (mean age 56.7 +/- 11.7; 80% men) with acute st elevation MI were included into the study. Patients were categorised into four 6-h increments (00:01-06:00; 06:01-12:00; 12:01-18:00 and 18:01-24:00 hours).

RESULTS

Onset of MI exhibited significant circadian variation among four time periods (p < 0.001), demonstrating afternoon peak (between 12:01 and 18:00 hours) and trough between 00:01 and 06:00 hours. Incidence of MI between 12:01 and 18:00 hours was significantly higher when compared with other three 6-h periods (p = 0.001). Incidence of MI between 00:01 and 06:00 hours was significantly lower when compared with other three 6-h periods (p = 0.001). Incidence of MI between 12:01 and 18:00 hours was 1.64 times that of average frequency of the remaining 18:00 hours of the day and 2.3 times that of frequency between 00:01 and 06:00 hours. When analysed for the subgroups of the study sample, only smoking blunted the afternoon peak.

CONCLUSIONS

Instead of early morning peak in western countries, there is afternoon predominance in circadian variation of MI in a Turkish cohort. It may be related with genetic and/or demographic characteristics of Turkish population. Further studies are required to determine underlying pathophysiological mechanisms causing these differences in chronobiology of MI among populations.

Ethnic disparities in incidence of stroke subtypes: Auckland Regional Community Stroke Study, 2002–2003

BACKGROUND

Limited population-based data exist on differences in the incidence of major pathological stroke types and ischaemic stroke subtypes across ethnic groups. We aimed to provide such data within the large multi-ethnic population of Auckland, New Zealand.

METHODS

All first-ever cases of stroke (n=1423) in a population-based register in 940 000 residents (aged 15 years) in Auckland, New Zealand, for a 12-month period in 2002-2003, were classified into ischaemic stroke, primary intracerebral haemorrhage (PICH), subarachnoid haemorrhage, and undetermined stroke, according to standard definitions and results of neuroimaging/necropsy (in over 90% of cases). Ischaemic stroke was further classified into five subtypes. Ethnicity was self-identified and grouped as New Zealand (NZ)/European, Maori/Pacific, and Asian/other. Incidence rates were standardised to the WHO world population by the direct method, and differences in rates between ethnic groups expressed as rate ratios (RRs), with NZ/European as the reference group.

FINDINGS

In NZ/European people, ischaemic stroke comprised 73%, PICH 11%, and subarachnoid haemorrhage 6%, but PICH was higher in Maori/Pacific people (17%) and in Asian/other people (22%). Compared with NZ/European people, age-adjusted RRs for PICH were 2.7 (95% CI 1.8-4.0) and 2.3 (95% CI 1.4-3.7) among Maori/Pacific and Asian/other people, respectively. The corresponding RR for ischaemic stroke was greater for Maori/Pacific people (1.7 [95% CI 1.4-2.0]), particularly embolic stroke, and for Asian/other people (1.3 [95% CI 1.0-1.7]). The onset of stroke in Maori/Pacific and Asian/other people began at significantly younger ages (62 years and 64 years, respectively) than in NZ/Europeans (75 years; p<0.0001). There were ethnic differences in the risk factor profiles (such as age, sex, hypertension, cardiac disease, diabetes, hypercholesterolaemia, smoking status, overweight) for the stroke types and subtypes.

INTERPRETATION

Compared to NZ/Europeans, Maori/Pacific and Asian/other people are at higher risk of ischaemic stroke and PICH, whereas similar rates of subarachnoid haemorrhage were evident across ethnic groups. The ethnic disparities in the rates of stroke types could be due to substantial differences found in risk factor profiles between ethnic groups. This information should be considered when planning prevention and stroke-care services in multi-ethnic communities.

Circadian analysis of myocardial infarction incidence in an Argentine and Uruguayan population

Background

The occurrence of variations in the spectrum of cardiovascular disease between different regions of the world and ethnic groups have been the subject of great interest. This study report the 24-h variation of myocardial infarction (MI) occurrence in patients recruited from CCU located in Argentina and Uruguay.

Methods

A cohort of 1063 patients admitted to the CCU within 24 h of the onset of symptoms of an acute MI was examined. MI incidence along the day was computed in 1 h-intervals.

Results

A minimal MI incidence between 03:00 and 07:00 h and the occurrence of a first maximum between 08:00 and 12:00 h and a second maximum between 15:00 and 22:00 h were verified. The best fit curve was a 24 h cosinor (acrophase ~ 19:00 h, accounting for 63 % of variance) together with a symmetrical gaussian bell (maximum at ~ 10:00 h, accounting for 37 % of variance). A similar picture was observed for MI frequencies among different excluding subgroups (older or younger than 70 years; with or without previous symptoms; diabetics or non diabetics; Q wave- or non-Q wave-type MI; anterior or inferior MI location). Proportion between cosinor and gaussian probabilities was maintained among most subgroups except for older patients who had more MI at the afternoon and patients with previous symptoms who were equally distributed among the morning and afternoon maxima.

Conclusion

The results support the existence of two maxima (at morning and afternoon hours) in MI incidence in the Argentine and Uruguayan population.

Ethnic or Racial Differences Revisited

Ethnic or racial differences in pharmacokinetics and pharmacodynamics have been attributed to the distinctions in the genetic, physiological and pathological factors between ethnic/racial groups. These pharmacokinetic/pharmacodynamic differences are also known to be influenced by several extrinsic factors such as socioeconomic background, culture, diet and environment. However, it is noted that other factors related to dosage regimen and dosage form have largely been ignored or overlooked when conducting or analysing pharmacokinetic/pharmacodynamic studies in relation to ethnicity/race. Potential interactions can arise between the characteristics of ethnicity/race and a unique feature of dosage regimen or dosage form used in the study, which may partly account for the observed pharmacokinetic/pharmacodynamic differences between ethnic/racial groups. Ethnic/racial differences in pharmacokinetics/pharmacodynamics can occur from drug administration through a specific route that imparts distinct pattern of absorption, distribution, transport, metabolism or excretion. For example, racial differences in the first-pass metabolism of a drug following oral administration may not be relevant when the drug is applied to the skin. On the other hand, ethnic/racial difference in pharmacokinetics/pharmacodynamics can also happen via two different routes of drug delivery, with varying levels of dissimilarity between routes. For example, greater ethnic/racial differences were observed in oral clearance than in systemic clearance of some drugs, which might be explained by the pre-systemic factors involved in the oral administration as opposed to the intravenous administration. Similarly, changes in the dose frequency and/or duration may have profound impact on the ethnic/racial differences in pharmacokinetic/pharmacodynamic outcome. Saturation of enzymes, transporters or receptors at high drug concentrations is a possible reason for many observed ethnic/racial discrepancies between single- and multiple-dose regimens, or between low- and high-dose administrations. The presence of genetic polymorphism of enzymes and/or transporters can further complicate the analysis of pharmacokinetic/pharmacodynamic data in ethnic/racial populations. Even within the same dosage regimen, the use of different dosage forms may trigger significantly different pharmacokinetic/pharmacodynamic responses in various ethnic/racial groups, given that different dosage forms may exhibit different rates of drug release, may release the drug at different sites, and/or have different retention times at specific sites of the body. It is thus cautioned that the pharmacokinetic/pharmacodynamic data obtained from different ethnic/racial groups cannot be indiscriminately compared or combined for analysis if there is a lack of homogeneity in the apparent 'extrinsic' factors, including dosage regimen and dosage form.

Are there ethnic differences in the circadian variation in onset of acute myocardial infarction?

We hypothesised that ethnicity may influence the circadian pattern in acute myocardial infarction (MI), in view of the potential differences in genetic background, cardiovascular risk factors and cultural habits. To test our hypothesis, we studied 340 consecutive acute MI patients (268 males; mean age 61.6+/-12.3 years) from two different city-centre teaching hospitals in Birmingham (United Kingdom) and Alicante (Spain). A different circadian rhythm in MI onset was observed between the ethnic groups (p=0.001), with a significantly higher number of acute MI onset occurring between midnight and noon in British Caucasians and Indo-Asians. In contrast, Mediterranean Caucasians showed the converse circadian pattern, with most of the acute MI events happened between noon and midnight. Indo-Asian patients were the youngest patient group and showed the highest prevalence of diabetes and increased body mass index. Mediterranean patients had the highest prevalence of smokers but their mean serum cholesterol was the lowest. No differences in sex, blood pressure, height and weight were observed. In conclusion, this study has shown a different circadian rhythm in acute MI onset between 3 ethnic groups from two different city-centre teaching hospitals in Birmingham (United Kingdom) and Alicante (Spain) and, for the first time, provide data in the Indo-Asian population. Further studies are required to determine the pathophysiological mechanism(s) underlying these differences.