Are our food choices genetic?

Certain women have genes that can induce increased fat intake

Are our food choices genetic?

Obesity is a global pandemic, affecting millions of people in North America alone. It has been associated with medical conditions, such as cardiovascular complications and type 2 diabetes.

A recent study published in JAMA Pediatrics suggests that diet may not be the primary cause of obesity. Rather, the presence of a certain gene in women may also be a contributing factor.

Researchers at McGill University recently discovered that the fat intake of women is influenced by a gene called the DRD4 VNTR repeat 7. Although this gene alone does not cause women to become obese, the way that the gene affects the fat intake of the body depends on the environment that the carrier of the gene grew up in.

In particular, the presence of the DRD4 repeat 7 gene, present in approximately 20 per cent of the population, is informed by the carrier’s socioeconomic background. Women who carry the gene will have increased or healthier than average fat intake, if they grew up in a poorer or richer household, respectively. Lead author Laurette Dubê believes that the higher fat intake is due to the carrier’s food choices, rather than due to an underlying metabolic mechanism.

The study focused on 200 Canadian children, aged four, from Montreal, Quebec and Hamilton, Ontario. The researchers calculated the percentages of fat, protein, and carbohydrates the children had consumed based on diaries kept by their parents, while saliva tests were used to determine which children were carriers of the DRD4 repeat 7 gene. The quality of their socio-economic environment was estimated using family income.

“We found that among girls raised in poorer families, those with DRD4 repeat 7 had a higher fat intake than other girls from the same socio-economic background,” said Laurette Dubé.

Conversely, wealthier girls with the same gene variant had a lower fat intake than other girls in the same economic conditions. “This suggests that it’s not the gene acting by itself, but rather how the gene makes an individual more sensitive to environmental conditions that determines […] a child’s preference for fat and consequent obesity as the years pass by.”

The study confirms that DRD4 repeat 7 belongs to a larger class of plasticity genes, which increase or decrease the risk of certain medical conditions depending on an individual’s environment. The study confirmed that DRD4 repeat 7 was indeed a plasticity gene. These results provide a clearer explanation of the underlying causes of diseases like obesity, changing the  focus from the gene to the environment.

Boys with the DRD4 repeat 7 gene were not affected. Perhaps it is because girls need to be prepared to gain more weight to reproduce. Or perhaps it is too early to see the effects of the gene in boys at the tender age of four. Boys and girls gain weight at different stages in this age.

The outcomes of this study have further advanced our knowledge of obesity. Rather than merely blaming genetics, it is now evident that the environment in which one is raised plays a significant role on the development of obesity. It is therefore necessary to focus on both genetic and environmental factors to adequately prevent the pandemic.

Bill seeks to stop genetic discrimination

Bill S-201 currently in senate committee

Bill seeks to stop genetic discrimination

Picture this: U of T transfers you out because of your DNA. While it may sound like a twisted joke to most, this is exactly what happened to a Californian student back in 2012. He was told that because of his genes, he could no longer attend his middle school.

Although he was allowed back to school after his parents took this act of ‘genetic discrimination’ to court, it seems farfetched that a ruling was ever needed to resolve the issue in the first place. “It feels like I’m being bullied in a way that is not right,” he commented in an interview with NBCNews TODAY. It is worth noting that the decision was made because of a potential health risk to two students suffering from cystic fibrosis.

Bill S-201 is currently going through committee revision in the senate, after its second reading. It was first introduced in 2013 as S-218 and subsequently tabled, only to be reintroduced as the Genetic Non-Discrimination Bill by its sponsor Nova Scotia senator James Cowan, a long-standing liberal and lawyer by trade.

Dubbed as “an Act to prohibit and prevent genetic discrimination,” it was first referred to the Standing Senate Committee on Legal and Constitutional Affairs and later to the Standing Senate Committee on Human Rights. S-201 prohibits “genetic testing of any person as a condition in exchange for ‘providing goods or services to that individual’” (3.1a) or as part of a contract. This ensures that the results of genetic testing cannot be collected or used without written consent, though it does not apply to healthcare industry professionals such as physicians, pharmacists, or researchers.

The legislation pertains to giving citizens and employees the right to refuse genetic testing, the choice to disclose results of genetic testing, and the need for written consent if results are to be disclosed. This law would be enforced by a fine of up to $1 million and/or five years jail time if indicted; or up to $300, 000  and/or up to 12 months in jail for a summary conviction.

It also includes provisions to various conventions including the Canada Labour Code, the Privacy Act, the Canadian Human Rights Act, and the Personal Information Protection and Electronic Documents Act. According to the bill, this is done: to extend the aforementioned rights to employees; to incorporate these rights into our human rights; to ensure our personal information now includes our genetic material; and to classify information from genetic testing as personal health information.

According to experts and officials, we are currently lagging behind in terms of legal protection. In contrast, our neighbours to the south have already imposed a Genetic Information Nondiscrimination Act in 2008 and anti-discrimination laws for genetics and health insurance in most states. There are exceptions such as Alabama, which only prohibits the use of genetic information for denying coverage for applicants with sickle cell anemia, because it outlaws considering a “predisposition for cancer in risk selection or risk classification.”

In a 2014 Second Reading Debate, senator Cowan made reference to various pediatricians, geneticists, and even celebrities, notably Angelina Jolie, in an effort to convince his fellow senators that advancement in personalized genetic medicine and research will be beneficial to adults and children alike, but it was being hindered by fears of consequences in insurance and employment. Citing Dr. Ronald Cohn, co-director of Sick Kids Centre for Genetic Medicine, Cowan emphasized that the lack of protection against genetic discrimination was “preventing many Canadians from benefiting from extraordinary advances in medical research.”

On a separate occasion, prominent scholars and researchers have also voiced their concerns for the urgent need for protection against genetic discrimination, including bioethicist Kerry Bowman of the University of Toronto.

The senator ended his speech by raising questions of his own: “Does it achieve its objectives? Are there unanticipated consequences we should be aware of? And of course, are there ways in which the bill could be improved?”

While this bill will be beneficial in advancing genetic research and personalized medicine as it is intended, cautions remain in the broader political landscape.

Masters of our own design

A student’s perspective on the opportunities and risks of gene-editing

Masters of our own design

In 2012, the naturally occurring Cas9 enzyme was shown to be able to edit DNA sequences from a number of organisms by researchers at the Zhang Lab at MIT.

While this new powerful genetic editing tool holds great promise for treating an array of genetic disorders, such as HIV, cancers, and lesser known disorders like Duchenne muscular dystrophy; it also raises a number of ethical questions. When do we allow DNA editing in humans? To what extent will we allow for DNA editing to modify our genomes? Are we getting in the way of evolution, and what dangers could modifying our DNA bring about?  Most importantly, how will these changes to our genome get passed down to our offspring?

Due to these important and deeply controversial questions, scientists worldwide agreed to a moratorium on CRISPR-Cas9 gene-editing research in humans. For now, scientists have agreed to allow for clinical gene-editing research in all human cells, but have banned research that edits the germline — a scientific term for the DNA that is passed on from parent to offspring.

There is merit to this stance. The state of CRISPR-Cas9 research is still in its infancy, and needs to be perfected before it can be used in human therapeutics, and must pass a number of tests before it can be used to edit the human germline. CRISPR-Cas9 is not the first technology capable of editing DNA — its predecessors were zinc finger nucleases and TALENs, among other technologies — but so far it is the most promising. That said, biological techniques are not foolproof, and the CRISPR-Cas9 is not immune to off-target effects in the genome.

To put this in perspective, imagine that someone designs a computer program to edit the operating system on your computer. The program used is usually effective and edits the code it intends to. Although every once in a while, it modifies the code of something you need to function (for instance, Microsoft Word). But unlike a computer program or operating system, we cannot simply uninstall and then reinstall the program with the defective code. Instead, we are stuck with something dysfunctional, and the possibility that the defective code will actually interfere with other things that previously were working. To extend the analogy now, we’re left with a computer that cannot do basic word processing, and, scariest of all, cannot be fixed. To make matters worse, off-target effects in germline editing will likely be permanent not only in a single generation, but for generations to come.

The difficulty with CRISPR-Cas9 is that it holds so much promise, that researchers around the world are all racing to incorporate the technology into their work. As this race gets more competitive, the likelihood that someone will attempt something dangerous in the process of conducting ground breaking research increases. Thus the ban on germline editing.

Although CRISPR-Cas9 is possibly very dangerous, research cannot and should not be stopped. If we’re able to solve some of humanity’s most pressing concerns, such as HIV/AIDS, then we have a moral obligation to try. For that reason, the CRISPR-Cas9 gene-editing system might be the latest biomedical advancement to offer serious hope to millions. As long as scientists worldwide ensure that they conduct their research with caution and within certain limits, gene-editing research will be able to make significant advancements safely.

Recently, The Varsity had a chance to attend a discussion with Dr. Feng Zhang of the Zhang Lab, hosted by the Neuroscience Association for Undergraduate Students.

At the event, one student asked, the researcher about his opinion on using the CRISPR-Cas9 system to edit the germline. Dr. Zhang replied, stating that the importance of germline editing varies between groups of people, such as potential parents and policy-makers. As a researcher, he suggested that “we are not ready to use this  [CRISPR-Cas9 gene-editing] for medical treatment, because there are issues with specificity and efficiency,” citing the possibility of off-target effects. He highlighted the possibility of off-target effects causing other disorders, like cancer.

While the CRISPR-Cas9 system is undoubtedly one of the greatest biomedical breakthroughs of the past fifty years, if not the past century, it is not ready for public consumption. While nearly everyone wants this technology to be perfected, it cannot and should not be used until it is. When that day comes, the possibilities for treating disease and improving lives will be endless. It is for that reason, that CRISPR-Cas9 and gene-editing research needs to keep moving at its current pace, while being constrained by a few necessary rules.