Cardiovascular top research: Smoking makes people genetically altered, and they will be passed on to the next generation

The author of this article: Mai Jingting, deputy chief physician of the Department of Cardiology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University

Smoking, which reminds me of Wong Kar-wai's films, is always smoky, thick and deep.

"A person always has to smoke a different cigarette, know a different person, and understand a different life", this is the line in "In the Mood for Love".

"In the Mood for Love" stills: Shots of Maggie Cheung and Tony Leung smoking

However, scientific research tells us that after smoking, you really cease to be "you" and your genes and gene functions may have changed.

This is a study from Circulation, a leading journal in the cardiovascular field: Loss of Cardio-Protective Effects at the ADAMTS7 Locus Due to Gene-Smoking Interaction [1].

The idea that smoking increases the risk of coronary heart disease has been deeply rooted in people's minds, and unlike other articles demonstrating the association between smoking and coronary heart disease, the highlight of the study is to reveal the "Gene-Smoking Interaction" in the pathogenesis of coronary heart disease, that is, the interaction between genes and smoking (behavior).

Smoking can really change the function of human genes, and the protagonist of this change is called "ADAMTS7".

Smoking affects "good genes" and may be passed on to the next generation

The researchers included 29 clinical studies focusing on genes related to coronary heart disease risk, including 60,919 patients with coronary heart disease and 80,243 healthy controls, and selected 45 previously reported loci associated with coronary heart disease and 5 loci associated with smoking behavior, and meta-analyzed gene-smoking interactions through fixed-effect models.

There are two main research results: on the one hand, smoking affects "good genes", reduces their protective effect on cardiovascular disease, and increases the risk of coronary heart disease; On the other hand, the results show that these genetic influences can even be passed on to the next generation.

1. Smoking greatly reduces the function of "good" genes

People who don't want to try to quit smoking probably have all kinds of excuses. Some people think that they have good genes and don't have to worry about coronary heart disease. However, research has shown that "good" genes may also be greatly reduced in the face of smoking.

The protagonist of the study, "ADAMTS7", is a new metalloproteinase that can participate in the occurrence of atherosclerosis by promoting mechanisms such as the proliferation of coronary smooth muscle cells. The ADAMTS7 gene is upregulated and plays an important role in the pathogenesis of coronary heart disease.

The study found that at the location of the ADAMTS7-related locus on human chromosome 15, the T allele of the rs7178051 variant was strongly negatively correlated with the risk of coronary heart disease, and the rs7178051 variant accounted for 39% of the European population and reduced the expression of ADAMTS7 enzyme, thereby reducing the risk of coronary heart disease.

However, the results suggest that smoking significantly affects the protective effect of the RS7178051 variant against coronary heart disease.

This "protective" variant can reduce the risk of coronary heart disease by 12% in non-smokers, and if former smokers, even if they also have this "protective" variant, its protective function on cardiovascular disease will be reduced to only 5%.

Blue is the study subject who has never smoked, and red is the study subject who has smoked before, and the above figure shows the bias of its OR value

This is the first finding of the study: there is an interaction between genes and smoking, and smoking can greatly reduce the protective function of "good" genes.

2. Smoking can change genes and may be passed on to the next generation

As can be seen from the figure below, smoking can cause a range of genetic changes. For example, smoking an extra cigarette a day is significantly associated with changes such as 1.02 more A's for the SNP of chromosome 15 rs1051730, 0.37 more Gs for chromosome 10 rs1329650, and 0.33 Gs for chromosome 19 rs3733829.

The more cigarettes smoked, the more obvious the genetic changes, and there was a clear dose-response relationship. And these tangible changes in the genetic sequence will probably be passed on to the next generation.

Presentation of the results of another study

So while you're still in the lab doing CRISPR/Cas9 gene editing, ancient tobacco has been able to change the base pairs of smokers one by one.

Can change be reversed?

Since smoking can change genes and their functions, is quitting smoking still useful? Is it just a broken jar?

Although smoking leaves an imprint on human DNA, researchers have reviewed nearly 16,000 blood samples from 16 previous studies [2] and found that for those who quit, most genes automatically recover within 5 years after quitting smoking.

It is actually easy to understand that smoking interacts with genes, and the act of quitting smoking also interacts with genes. The same is true in the real world, as the time to quit smoking is extended, the risk of coronary heart disease and lung cancer gradually decreases. However, the study also found that a small number of genetic alterations persisted 30 years after quitting smoking.

So, the best thing is not to try smoking. If you don't smoke, don't smoke it in the future.

If you smoke, then...

Please avoid the harm of secondhand smoke to people around you, and do not smoke in indoor public places;

Please avoid smoking before childbearing, as smoking may alter your genes and potentially have adverse effects on the next generation.

Then, reconsider your reasons for smoking and trust the science:

If you smoke to be handsome, science tells you that smoking causes premature aging, small fresh meat becomes old bacon, and it can also cause ED.

If you smoke to refresh yourself and want to smoke when you think about problems, science tells you that smoking causes mental decline and stroke.

Source: Journal screenshot|Executive producer: Capricorn, Gyouza

Bibliography:

1. Loss of Cardio-Protective Effects at the ADAMTS7 Locus Due to Gene-Smoking Interaction. Circulation(2017)

2. Epigenetic Signatures of Cigarette Smoking. Circulation: Cardiovascular Genetics (2016), 9(5), 436 - 447