Skip main navigation
We use cookies to give you a better experience, if that’s ok you can close this message and carry on browsing. For more info read our cookies policy.
We use cookies to give you a better experience. Carry on browsing if you're happy with this, or read our cookies policy for more information.

Skip to 0 minutes and 8 secondsGenetic variation. We are all, as humans, very similar. Similar enough to be recognisable as humans. Much more similar than members of many other species are to each other. But still, we're all different. Different hair, different skin, different abilities, different likes and dislikes. So different as to be unique. Even identical twins who originate from the same fertilised egg are now thought not to be as genetically similar as previously thought.

Skip to 0 minutes and 50 secondsIn fact, no two individuals are exactly the same genomically. Why? Because of genetic variation. Genetic variation is a term used to describe the differences in the DNA sequence in each of our genomes.

Skip to 1 minute and 11 secondsAlthough there are many different changes to the genetic architecture which drive variation, the commonest type of genetic variation is what we call a single nucleotide polymorphism, or a SNP. A SNP is the substitution of a single base or nucleotide with another base or nucleotide. They occur throughout the genome, on average about every 300 bases. And many SNPs are seen frequently within the general population.

Skip to 1 minute and 44 secondsAs technology and our understanding of the genome improves, we're beginning to understand the importance of SNPs, although we still have a lot to learn. For instance, we know that genetic variation contributes to the evolution of species. Favourable characteristics are selected for, survive, and are passed on. This is what we call natural selection. In addition, we now know that some SNPs can predispose to the development of disease, whereas others can protect against disease. When the full set of detrimental and protective SNPs for a given disease are understood, we will be in a position to offer individuals SNP profiling to more accurately determine their risks for developing a given illness.

Skip to 2 minutes and 37 secondsWe are also beginning to understand that the combination of SNPs that an individual has will determine how they respond to some medicines, such as warfarin. We will talk much more about this in week four. But ultimately, we are still far more alike than we are different. If visitors from another planet landed on Earth, they would have a hard time telling us all apart.

Normal genetic variation

In this video, we learn about single nucleotide polymorphisms (SNPs), normal variation within the human genome and how we are beginning to understand that SNPs have a key role in disease development and our response to medicines.

Image: © SGUL, “A silhouette of human evolution created in Adobe Illustrator” by Tkgd2007. Licensed under CC BY-SA 3.0

Share this video:

This video is from the free online course:

The Genomics Era: the Future of Genetics in Medicine

St George's, University of London

Get a taste of this course

Find out what this course is like by previewing some of the course steps before you join:

  • Welcome to Week 1
    Welcome to Week 1
    video

    In this video, Lead Educator, Dr Kate Tatton-Brown welcomes learners to the course and explains the course aims and outcomes.

  • Did you know?
    Did you know?
    video

    Our resident scientist tells you his favourite genomics facts.

  • Errors in recombination
    Errors in recombination
    article

    This video describes how structural chromosome abnormalities occur when errors occur in recombination.

  • Responsibility in the genomic era
    Responsibility in the genomic era
    video

    In this tutorial, you will hear from Dr Carwyn Rhys Hooper on the concept of responsibility for health.

Contact FutureLearn for Support