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How large DNA banks help us to make breakthroughs possible

We know that in the majority of cases, the diseases that cause dementia are not the result of a single faulty gene passed down from our parents. Instead, it appears that small changes in several genes can contribute to disease development. These small genetic changes can affect a variety of different areas of our brain.

Even though risk is a complex mixture of genetics, lifestyle factors and our age, researching genetic risk factors provides scientists with vital clues to understand the biology behind the diseases. They are also the first step towards finding areas which may be useful targets for the development of new treatments.

But how do researchers find genetic risk factors?

The best way to understand genetic changes linked to diseases like Alzheimer’s is through large-scale studies. These studies are known as Genome-Wide Association Studies (GWAS) and at best, involve tens of thousands of DNA samples. The samples are donated by people with Alzheimer’s disease as well as those of a similar age and background but who don’t have the disease.

Researchers can then analyse the genetic makeup of the volunteers in precise detail. They use statistical analysis to look at each gene in our DNA code. The building blocks of a specific gene can vary between people and researchers are looking for variations in the same gene that occur more often in people with the disease than those without it. This flags up genes (the ones we call risk genes) that may be linked to an increased risk of developing a disease that causes dementia.

The bigger the better

The most important thing to remember about these genetic studies is “the more samples the better”.

Investigating Alzheimer’s disease genetics is especially complicated because, due to the multiple factors thought to contribute to disease development, having a risk gene does not necessarily mean you will get the disease. Changes in these risk genes can also be very subtle and therefore hard to detect.

For example, imagine you were investigating a gene. We know that for many genes there are slightly different variations of the same gene that occur naturally in the population. Let’s say for our gene of interest there are two – GENE1 and GENE2.

You suspect that having GENE2 may be a risk factor for Alzheimer’s disease. But because GENE2 is rare, or the effects are small, if you only look in a small number of people – you won’t be able to spot the affect!

However, if you did a larger study with many more samples, you may start to see differences. If you have a large enough set of samples, it may become clear that GENE2 does associate with the disease. These large-scale studies are especially useful for finding genetic changes which are rare or only contribute to Alzheimer’s in certain groups of people.

As researchers find more and more “risk genes” they can also start to look at how different combinations of these genes may work together to increase our risk of developing the diseases that cause dementia.

Genetics and environment

These large-scale genetic studies also allow scientists to tease apart genetic and environmental risk factors. For instance, it might be that all the samples from people with Alzheimer’s disease come from the same area. That means you cannot rule out that an environmental effect contributing to the disease. However, if your sample are from all over the world and from people with very different lifestyles, these environmental effects get diluted out. This makes the genetic effects clearer!

Gathering, maintenance and organisation of genetic data which are large enough to do these studies requires a monumental amount of management.

GWAS studies, along with other large-scale techniques, have already contributed greatly to our understanding of the genetics behind Alzheimer’s, but there is more left to be discovered. As well as helping us to understand why the disease develops, finding these genetic contributions to Alzheimer’s will aid researchers in finding new areas which can be used as targets for treatment.

 

Since 2014, Alzheimer’s Research UK has supported Prof Kevin Morgan at the University of Nottingham, to build and maintain a huge collection of DNA samples – known as the Alzheimer’s Research UK DNA Bank. DNA banks are an essential tool for dementia research, as often the samples and data are available for scientists all over the world to use.  The bank run by Prof Morgan has already helped to identify over 20 new Alzheimer’s risk genes, with more discoveries to come!

This is why Alzheimer’s Research UK encourages and funds the maintenance of large DNA banks such as the one managed by Prof Morgan and his team. The more data available, and the more varied it is, the better chance we have of understanding the genetics of the diseases that cause dementia and translating that understanding into benefits for people with dementia.

6 Comments

  1. Mike Pye on 16th May 2015 at 10:07 am

    Are they looking for more DNA samples from Alzheimers patients?

    • Alzheimer's Research UK Editor on 17th May 2015 at 11:14 am

      There are many ways that people with Alzheimer’s can get involved in current research, and this may include providing a DNA sample. The best way to get involved in research is to sign up to Join Dementia Research.

      Anybody with or without dementia can register their interest in being approached about research studies they match to by simply registering with some basic demographic and health information.

      Visit http://www.joindementiaresearch.nihr.ac.uk or call our Dementia Research Infoline on 0300 111 5 111 for more information about the scheme. Thank you for your interest.

  2. Amanda Johnson on 22nd August 2016 at 7:06 pm

    I am interested in registering my interest in becoming part of a Dementia Research Project. I do not have dementia and am a 54 year old white female. There does not appear to be any history of dementia in my family.

    • ARUK Editor on 23rd August 2016 at 7:45 am

      If you are interested in getting involved in research, there are lots of dementia studies recruiting through a nationwide research register called Join Dementia Research. This service is designed to match people to appropriate research studies, and anyone, with or without dementia, can register their interest as a volunteer. The research studies available are happening all across the UK and can range from doing memory tests to having brain scans, or even taking part in drug trials. You can find out more about this service on our website, http://www.alzheimersresearchuk.org/about-dementia/helpful-information/getting-involved-in-research/, or if you prefer, you can register over the telephone by calling our Dementia Research Infoline on 0300 111 5 111.

  3. ARUK Editor on 23rd August 2016 at 8:13 am

    If you are interested in getting involved in research, there are lots of dementia studies recruiting through a nationwide research register called Join Dementia Research. This service is designed to match people to appropriate research studies, and anyone, with or without dementia, can register their interest as a volunteer. The research studies available are happening all across the UK and can range from doing memory tests to having brain scans, or even taking part in drug trials. You can find out more about this service on our website, http://www.alzheimersresearchuk.org/about-dementia/helpful-information/getting-involved-in-research/, or if you prefer, you can register over the telephone by calling our Dementia Research Infoline on 0300 111 5 111.

  4. Molly McDonald on 1st December 2017 at 4:35 pm

    This is such an interesting study. We need to spread awareness of the crippling effects of dementia.

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About the author

Fiona Calvert

Team: Science news