Elsevier

Preventive Medicine

Volume 39, Issue 3, September 2004, Pages 458-464
Preventive Medicine

Public interest in genetic testing for susceptibility to heart disease and cancer: a population-based survey in the UK

https://doi.org/10.1016/j.ypmed.2004.04.051Get rights and content

Abstract

Background. Given the current concerns about the clinical validity of commercially marketed genetic tests for multifactorial diseases, there is a surprising dearth of information about what public demand might be for genetic tests for any complex diseases other than cancer. The aim of this study was to examine interest in genetic testing for the most common multifactorial disease, heart disease, and to compare it with interest in testing for cancer in a general population sample that had not received detailed information about genetic tests.

Methods. Interest in genetic testing for heart disease susceptibility was surveyed and compared to interest in genetic testing for cancer susceptibility among a nationally representative sample of 1,960 British adults as part of the Office for National Statistics Omnibus survey.

Results. Sixty-nine percent of respondents expressed interest in being tested for genetic susceptibility to heart disease. Men, people aged 45–60 years, those with less education, and those with a family history were most interested in genetic testing for heart disease. Sixty-four percent of respondents expressed interest in genetic testing for susceptibility to cancer, and gender, age, and education, but not family history, were associated with interest.

Conclusions. Interest in genetic testing for susceptibility to both heart disease and cancer was high, with the most educated individuals being the least interested in testing. Although the shift toward the ‘expert patient’ is actively encouraged and consistent with today's health policies, there is considerable and justifiable concern about some of the genetic tests for multifactorial diseases that are currently being marketed directly to the public. The high level of initial interest in the general public found in this study supports the need for a public education program around genetic testing for multifactorial diseases.

Introduction

Much of molecular genetics in medicine is concerned with inherited disorders that are caused by a defect in a single gene or chromosome (‘monogenic’ or ‘single-gene’ disorders). There are currently around 200 genetic tests available, most of which are for single gene disorders. Carrier genetic testing for cystic fibrosis, for example, provides couples with information about the chances of cystic fibrosis in their future children. Other types of genetic tests include predictive genetic tests that give individuals with a family history of a late-onset single gene disorder, such as Huntington's chorea, the option of knowing whether they themselves will develop the disease in the future. In addition to the diseases caused by single genes of total penetrance, susceptibility to some rare subtypes of common diseases, such as some forms of cancer, can also be conferred by a single defective gene of partial penetrance. For example, 5% of breast cancer cases are caused by a mutation in the BRCA1 gene, and genetic tests can inform some relatives of breast cancer patients with this mutation about their own risk.

However, most of the more common diseases also have a genetic component, acting in concert with environmental factors, and there is a substantial research effort underway investigating the genetic components. For example, in addition to the known environmental contributors to susceptibility to heart disease such as smoking and stress, several genes conferring an increased susceptibility to heart disease have been identified [1]. These include both monogenic causes, such as the rare mutations in the low density lipoprotein receptor gene that cause Familial Hypercholesterolemia [2] and “polygenic” variants that are common but of small to modest effect on risk, such as APOE [3] and GSTM1 [4]. Testing for such genetic “risk factors” may be used clinically in the future to identify and target people at increased risk [5], [6], much in the way that risk factors such as blood pressure or cholesterol concentrations are used today [7].

While it is widely recognized in the public health sector that genetic tests for multifactorial diseases will not be available clinically for at least 5–10 years, some commercial organizations are already seeking to develop and market such tests directly to the public. For example, one US-based company has already developed a SNP panel for cardiovascular disease and is marketing this test (calling the results a ‘CardioGenomic Profile’) and other similar tests through health care professionals. Another company is using the Internet to market its ‘tailored’ dietary supplements directly to the public. The so-called ‘Nutragenetic Report’ is allegedly based on tests for genes associated with increased risk of cardiovascular disease. Yet another company has been providing lifestyle advice directly to the public from genetic tests for genes possibly involved in the carcinogenic metabolic pathways [8].

In response to these developments in the commercial sector, the UK Government's independent advisory body on human genetics, the Human Genetics Commission (HGC), has advised an overhaul of the regulation of genetic tests provided direct to the public [9]. One of their main concerns about ‘direct genetic testing’ is that “misinterpreted or erroneous predictive health information which overstates the role of genetics in developing common diseases may result in delays in seeking proper medical advice (or seeking unnecessary medical treatment) or making expensive and unproven dietary or lifestyle changes” (p7). The HGC recognizes that genetic testing is developing against a background that increasingly encourages people to take more responsibility for their own health, and notes that public demand, coupled with commercial pressures, may lead to tests being offered directly to consumers before they are available clinically (p16).

One important consideration in developing guidelines for the effective oversight of direct genetic testing is determining the likely level of public demand for genetic tests for common diseases and the characteristics of people who are particularly interested in testing and might therefore benefit from educational interventions. There is an emerging body of literature examining public interest in genetic testing and investigating the demographic and other factors that are associated with interest. Most of these studies examine genetic testing for cancer, either a specified cancer, such as breast [10], colon [11], [12], or prostate cancer [13], or for cancer risk in general [14], [15]. Interest in genetic testing is usually reported to be high among both clinical and general population samples. Some studies have found interest to be higher among people with a family history of the cancer in question, while other studies have found no difference. The reason for these mixed findings is not clear, but it may be in part due to differences in the characteristics and source of the population being studied (e.g., high-risk clinic populations vs. general populations). While the findings from both the high-risk samples and the wider population are interesting, some of the population-based surveys have been criticized for providing too little information to participants concerning the limitations of testing, and it is indeed likely that some people who show an initial interest in testing will decide against it once they learn, for example, that the tests cannot give them a definitive, yes or no, answer. Nonetheless, it is important to know about the public's interest even without detailed information, given that it may reflect the reality that commercial companies currently providing these tests are not necessarily providing it.

While the body of research examining interest in testing for cancer is growing, there is still very little research on attitudes and levels of interest for any other multifactorial diseases, such as heart disease, despite the focus of the commercial sector on genes associated with cardiovascular function. The aim of the current study was to examine general population interest in testing for the two multifactorial diseases that are responsible for most deaths in Western countries—heart disease and cancer. In view of limited information provided for some commercial testing, detailed information about genetic tests was not provided before decision-making.

Previous studies have found interest in genetic testing for susceptibility to cancer to be higher among younger adults, women, and those with more years of education. In the absence of any other guidance, we hypothesized that the same factors that predict interest in testing for cancer would predict interest in heart disease testing. In addition, we hypothesized that people might be more interested in genetic testing for heart disease than for cancer on the basis that heart disease tends to be regarded as more controllable and less terrifying than cancer.

Section snippets

Participants and procedure

A series of questions on genetic testing was included in the September 2002 Omnibus Survey. The Omnibus Survey is a monthly multipurpose survey developed by the Office for National Statistics for use by the government and nonprofit making organizations, and uses a stratified random probability sample. Previous Omnibus surveys have addressed a range of health-related issues, including obesity [16], oral health [17], and health status [18]. Of the 3,000 addresses that were selected in September

Results

The 1,960 respondents ranged in age from 16 to 96 with a mean age of 47 years (SD = 18.2 years). Just over half (51%) were female, and the majority (94%) were Caucasian. Table 1 shows the demographic characteristics of the sample: 32% had no formal qualifications; 27% had GCSEs or equivalent; 29% had A-levels or equivalent; and 13% had a degree or equivalent. When asked whether they had any close family members with heart disease: 42% (830) said ‘yes’; 52% (1,017) said ‘no’; 2% (41) said ‘don't

Discussion

This is the first study to examine interest in genetic testing for heart disease risk in parallel to interest in genetic testing for cancer risk. The majority of people in this survey said that they would be interested (69%) in genetic testing for heart disease risk, and as hypothesized, this was slightly higher than their interest in testing for cancer (64%). Heart disease tends to be perceived as less threatening and more preventable than cancer, and this, combined with the observation that

Acknowledgements

This work was supported in part by a grant from the Department of Health and Department of Technology and Industry to the London IDEAS Genetics Knowledge Park. SCS, JW, and MJJ are supported by Cancer Research UK. SEH is supported by the British Heart Foundation (RG2000/015). There are no competing interests to declare.

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