• Question: Does DNA hold information about illnesses or diseases you could possibly get in the future?

    Asked by abiiii on 1 May 2020.
    • Photo: Kyren Lazarus

      Kyren Lazarus answered on 1 May 2020:


      Interesting question. There are many companies who will sequence your DNA and based on that information give you a probability of you getting a certain disease or illness. For certain cancers there if you have a heritable mutation you may be more prone to developing that cancer, however for most diseases or illnesses there is tight balance between the information and various environmental factors like smoking that could vary this information can increase the risk of certain diseases.

    • Photo: Ailith Ewing

      Ailith Ewing answered on 1 May 2020:


      In short, yes it can. Whilst about 99.9% of your DNA will be the same as other people’s. That still means that about 3 million of your DNA bases are different from somebody else’s! It’s these differences that give people different eye colours, hair colours and affect a huge variety of other things. But as you say, some changes in our DNA can mean that we are MORE or LESS LIKELY to develop illnesses or diseases in the future than other people. What’s important to know though is that these changes don’t usually mean that we definitely will or won’t get the disease. Instead, they can affect our risk of developing the disease. Just like eating unhealthily will increase our risk of getting ill. All these risks should be considered together.

    • Photo: Max Furst

      Max Furst answered on 1 May 2020:


      The answer is a clear “yes”. Many diseases that stem from a “genetic disorder” will only manifest later in life. One of many examples is Huntington’s disease: it stems from a mutation in a gene encoding for a protein called huntingtin. Although it’s still not really clear what that protein is actually needed for, it turns out that it is pretty important for humans. People that have a certain modification of that gene will produce a different form of that protein, which, when broken down in the course of a normal degradation within the cell, leaves leftover pieces that, over time, accumulate in nerve cells and cause severe symptoms like dementia, at a certain point in adult life. This is a pretty clear cut case: if you get your genome sequenced (you can do it for ~£1000 these days), you’ll see the mutation that causes Huntington’s and you know you’ll get it.
      In other cases, especially cancers, it’s much less clear: you’ll have some genetic variations that can increase your risk to get the disease, but it’s not garantueed. Researchers work a lot in this area and the more we find out about the function of all the proteins in our body, the better we will understand what a certain genetic background (i.e. the exact DNA sequence your genome has) means with respect to diseases one may later develop.

    • Photo: Niloofar Ganji

      Niloofar Ganji answered on 2 May 2020:


      Yes, DNA contains genes that involve mutations (mistakes in the gene!) which that will lead to a disease. There are many diseases like this, such as cancer. Your question was considered by many scientists years ago and now they are thinking about how to prevent progression of diseases by being able to prevent them in early steps.

    • Photo: Bilal Ahsan

      Bilal Ahsan answered on 2 May 2020:


      Fantastic and elaborated answers already!
      DNA does hold information for genetic/inherited disease, and we are already testing such disorders routinely in hospitals – especially in very early stages of life when the baby is inside the mother’s womb. Based on certain mutations in parental DNA, for certain cancers, we are also capable of predicting the probability of having same cancer in the children in their old age.
      However, our DNA does not hold information about the illness that involves exposure to infectious agents, such as bacteria, viruses, fungi and parasites.

    • Photo: Nina Rzechorzek

      Nina Rzechorzek answered on 2 May 2020: last edited 2 May 2020 3:31 pm


      Hi abiiii – as others have said – yes it does; but the most common diseases you hear about are thought to be ‘polygenic’ in that they involve many different genes – a change in just one of these genes is not enough on its own to cause the disease, but changes in multiple genes, each of which ‘modifies the risk’ of getting a disease, in combination with environmental risk factors, can increase the chance of getting e.g. some types of cancer, diabetes, cardiovascular disease. More info here:
      https://www.who.int/genomics/public/geneticdiseases/en/index3.html
      There are some less common ‘hereditary’ or ‘familial’ diseases (including some cancers, neurodegenerative diseases, heart diseases, developmental diseases and many others), that are caused by just one mutant gene – we call these ‘monogenic diseases’ and you can read more about these here:
      https://www.who.int/genomics/public/geneticdiseases/en/index2.html
      Our DNA can can also tell us if there are abnormalities in whole chromosomes, or the number of chromosomes that can lead to certain syndromes, e.g. Down syndrome:
      https://www.who.int/genomics/public/geneticdiseases/en/index1.html
      The other major advantage of whole-genome sequencing is that we can even learn about diseases that are caused by mutations in the DNA that sits ‘between’ protein-coding sequences – the intronic regions. These are much harder to find, but a recent and important example is a type of hereditary motor neurone disease (MND) caused by mutations in the intronic (promoter) region of the gene C9orf72; these lead to an abnormal expansion of the genetic code and is currently the most common cause of hereditary MND. MND is a devastating, fatal, rapidly progressive neurodegenerative disease. You can read more about genetic forms of MND here:
      https://www.mndassociation.org/about-mnd/what-is-mnd/inherited-mnd/
      And more about C9orf72 here:
      https://en.wikipedia.org/wiki/C9orf72
      It’s important to note that for the vast majority of cases of MND, there is no known underlying genetic cause (although there may be more yet to discover)
      There are also several research groups looking at our genetic susceptibility to infection, including for COVID-19:
      https://genomicc.org/

    • Photo: Emma Lloyd

      Emma Lloyd answered on 2 May 2020:


      Great question! In theory, yes, our DNA sequence can tell us about potential genetic diseases a person may have. Two good examples are Huntington’s disease in which patients have a certain number of amino acid repeats in a specific gene and the BCRA genes which are associated with a higher risk of breast cancer.

    • Photo: Darren Thomson

      Darren Thomson answered on 4 May 2020:


      Yup! Babies in the womb of expectant mothers are commonly tested to see if they have a mutation in certain genes, which we know will lead to a likely chance that the child may be born with a particular disease or condition such as cystic fibrosis.

      We also know, through comparing sick patient genomes with a normal healthy genomes, that a genetic mutation found in the sick patients (and absent on heathy individuals) is associated with the disease. We found this with patients who are suceptible to a fungal lung disease called Aspergilosis; https://www.nc3rs.org.uk/development-new-experimental-models-understand-genetic-basis-allergic-bronchopulmonary-aspergillosis

      Hope this helps!

    • Photo: Eleanor Raffan

      Eleanor Raffan answered on 4 May 2020:


      Yes, but not all the answers. Sometimes people’s DNA includes mutations that mean they will definitely get a particular condition. That’s fairly rare though. More commonly, lots of different areas of our DNA give us a tiny increase or decrease in the risk we will develop a disease. The overall effect of those increases and decreases usually comes as making it more or less likely we will develop a condition.

      I study obesity. There are some rare mutations that mean people with those mutations are desperately hungry all the time and they simply cannot stay at a healthy weight. Those are very unusual conditions though. More commonly, whether someone is prone to overeating is the result of having lots and lots of different changes across their DNA which together make them a little hungrier or a little more likely to make unhealthy food choices. Over time, and if they live in an environment where there is lots of food available – and particularly if there is lots of unhealthy food available – they will gain weight. Because of their genetic makeup, that means there are some people who find it a lot harder to maintain a healthy weight.

    • Photo: Kim Liu

      Kim Liu answered on 4 May 2020:


      This is a great question, with countless great answers I can’t really add to 🙂 I’d like to copy what Eleanor said above because I think it’s important – DNA does not hold all the answers; the way you live your life matters a lot ~
      Also – this hopefully highlights how important your personal genetic information is: what if health insurance is given based upon your DNA code? Thankfully – the UK doesn’t really need health insurance, but this is already proving to be an issue in the US!

    • Photo: Ozge Ozkaya

      Ozge Ozkaya answered on 5 May 2020:


      Yes. There are many diseases that may have a genetic cause that has not been identified yet.

    • Photo: Ana Cruz

      Ana Cruz answered on 5 May 2020:


      Hi Abi, you have already had such great responses. I hope you have found them helpful. I don’t have much to add but will mention that sometimes changes that happen “above” your DNA, called epigenetic changes can also influence disease. This is a newer field (Epigenetics) and there is a lot stronger evidence to suggest that certain mutations (errors/deletions/additions) in your DNA are linked to disease, but a lot of research is being done on “outside influencer” on DNA too. Changes to DNA can not only cause some diseases as mentioned in other answer but also increase your risk of developing those conditions later in life.

    • Photo: Donna MacCallum

      Donna MacCallum answered on 7 May 2020:


      Interesting… many disease have genetic (DNA) causes which also require certain lifestyle or environmental changes… so some diseases like type 2 diabetes do not show up unless you become overweight. Some diseases need a number of different genes to be in the same person to get disease too.
      Many diseases are infectious diseases (like malaria and coronavirus) – our DNA may determine how ill we might get, but you still have to be exposed to the disease to get it

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