how can DNA help us discover more about diseases?

Question: how can DNA help us discover more about diseases?
- Keywords:
  disease,
  DNA,
  genetics
Asked by anon-244767 on 29 Apr 2020.
- Alena Pance answered on 29 Apr 2020:
  
  We can of course treat diseases without knowing the actual cause but the symptoms. And this works quite well for some things, like a cough, we don’t need to understand what is causing the cough and just giving some soothing syrup we can make it better and because it generally is caused by temporary issues, it will eventually go away.
  But more serious illness needs more than just treating the symptoms because the patient will not get better and that means living under some sort of treatment all the time for some diseases. It is only knowing the cause that will make it possible to cure the disease rather than just treat it. This is where DNA is extremely useful because many times diseases are caused my genetic changes or mutations in specific genes. We can get a good understanding of this by comparing genome sequences of many people which can reveal those differences that some people have that can be associated to certain conditions. Once we know the cause, then the hunt starts for ways to correct or overcome the problem to cure the disease.
- Laura Devlin answered on 29 Apr 2020: last edited 29 Apr 2020 9:29 pm
  
  To add to this answer, we can also look to DNA to help us discover whether certain mutations/errors, predispose (make it more likely) for people to get a particular disease/illness, for example heart problems. This could help when thinking about preventative treatments (i.e trying to stop people from developing the disease in the first place).
  
  This is very complex problem to tackle, as lots of things can predispose you to disease, including environmental factors such as diet, so the area still requires a lot of research before there are solid answers.
- Lucy McGowan answered on 29 Apr 2020:
  
  This is a great question and there are lots of different answers to it. I will give just a few examples.
  
  Our DNA is like a big recipe book, with each gene (a single recipe) telling the cells in our bodies what to do. If we get mutations in our DNA, this changes the instructions that cells receive. Some mutations are good, some mutations make no difference and some mutations can be very damaging. By studying the DNA we can understand what types of mutations are damaging.
  
  If we find a disease-causing mutation in a certain gene, it tells us a lot about what that gene does and why it’s important. For example, people who have a mutation in the gene for Collagen 1 have very weak bones. This tells us that Collagen 1 is important for making healthy bones. By studying DNA in this way, it highlights potential new ways we can treat diseases for which there are no medicines.
  
  Studying DNA is also a really good tool for helping us predict diseases. By looking at people’s DNA, we can detect “risk factors” for developing a certain disease in later life. For example, people with a mutation in the gene BRCA 1 are much more likely to get breast cancer. If we know a person has this mutation, we can make sure they receive preventative medical care to stop them from getting a disease before it strikes.
  
  DNA can also tell us about infectious diseases, like viruses, bacteria and parasites. Genetic sequences change from generation to generation (mutations) and this is what drives evolution. Unfortunately, this is also what creates new types of infectious diseases which can spread from person to person. By studying the DNA from infectious diseases, we can find out about where they came from, how they spread and most importantly how we can stop them in their tracks and treat people who get infected.
- Gavin McStay answered on 29 Apr 2020:
  
  If we know the DNA sequence of a gene that causes a disease we can then begin to understand what that gene does and which other genes it works with in a cell. Knowing this information we can try and research treatments for that disease.
- Amy Mason answered on 30 Apr 2020:
  
  This is one of the coolest areas in which I do research. There are multiple ways you can use DNA to discover more about diseases.
  You can look for direct genetic causes e.g. if having a certain sequence in your genes makes you much more likely to get something like breast cancer, then we can investigate what those genes do and try to work out why they cause cancer, and how we can prevent/treat it.
  Some diseases don’t have genetic causes because they are caused by outside causes, like parasites or viruses, or by lifestyle choices like smoking or drinking.
  But by using a technique called Mendelian randomization we can still use genetics to understand what is happening. For example, there are some genes that make you more likely to smoke so we can divide the population into two based on their genetic predisposition to smoking and then look at whether the people who are likely to be higher smokers also have more lung cancer. This is almost like a randomized trial where the “randomization” stage happens at conception.
  Similarly, by finding genes that mimic the effects of drugs, we can predict how people will be affected by new drugs before we do drug trials (i.e. if both drug A and gene B lower blood pressure in the same way, then taking drug A will be like changing to the population with gene B)
- Nicole Wheeler answered on 30 Apr 2020:
  
  Great question! And there are some great answers here already. I would add that for infectious diseases, we can also look at the DNA of whatever is causing the infection to better understand cases of disease in people.
  
  For example, in England, if you go to the doctor for an upset stomach and are found to be infected with salmonella, the DNA of this salmonella is sequenced. This lets people working in public health see if other people have been infected by the same “strain”, meaning a really close relative of the bacteria infecting you.
  
  If lots of people show up to the doctor with the same strain of a bacterial infection, this suggests they’ve all become infected from a common source. This would result in an investigation to find the source, for example contaminated meat or salad, or maybe an unhygienic restaurant. Once we know the source, we can work to make sure more people don’t become infected.
- Ben Wiggins answered on 1 May 2020:
  
  An interesting question! I guess you can think about this in two ways: how knowing about our own DNA can help us understand disease, and how knowing about the DNA of disease-causing bacteria and viruses can help understand disease.
  
  Like the other scientists have said, our DNA is like a recipe book. Each gene is really just a long string of chemicals called bases which provide the instructions that make all the different proteins our cells need to function. Each protein has a specific role within the cell to allow it to do its job. For example, muscle cells make ‘contractile’ proteins that allow our muscles to contract, and brain cells called neurons make neurotransmitters – the chemicals that are responsible for the brain to do its job of thinking, acting and feeling. By knowing exactly what genes are made into proteins in each cell type, we know how the body works in health. Then we can compare what happens to these genes in different diseases to see if there is a link between not having (or having too much of) certain genes in certain diseases. Scientists commonly do this in by looking at the genetic sequences of many people and then seeing if any variations in the genes precise instructions are found more commonly in those people with certain diseases (this is what ‘genome wide association studies or GWAS are). For example thanks to this we know certain gene variations are more common in people who develop breast cancer, and certain other gene variations make people more likely to get diseases of the immune system.
  
  From the other side, if we can understand the exact instructions that different disease causing viruses or bacteria use to infect our cells and cause damage, we can better design strategies to stop them. As a topical example, right now scientists are working hard to understand how the genetic code of the novel coronavirus (coronaviruses actually use RNA not DNA, but the same principle applies) can be used to enhance the immune response to the virus and create an effective vaccine. They have found that the genes that code for the coronavirus spike protein is important for the virus to bind to and enter our lung cells. Therefore they are focussing on encouraging an immune response where immune cells bind to and cover up these coronavirus spikes and stop it being able to get into our cells and thus providing immunity.