What is genomics?

Please take your time to work through this step and the following step. Then the videos in 1.9 will recap the main points.

What is genomics?

As patients, research participants or their representatives, we’re often invited into conversations where genetics or genomics are mentioned—sometimes without much explanation. This part of the course sets out key concepts in genomics so we can feel more comfortable when these topics come up.

Genomics vs genetics

The human genome contains 3.2 billion chemical building blocks (together known as DNA, deoxyribonucleic acid). Most of these (99.9%) are the same in everybody. Where there are differences, these influence our unique characteristics. Some of these differences are known to have health impacts. Many of the differences are not yet fully understood.

The first step to understanding the genome is to ‘sequence’ it. This means writing down the 3.2 billion DNA letters in order. This is known as Whole Genome Sequencing (WGS). The first project to sequence a human genome took an international team of researchers about 12 years. Today, powerful computing technology can do this within a day.

Located within the genome are strings of DNA bases known as ‘genes’. These genes are responsible for providing the instructions for making proteins in our bodies or sending instructions to other cells. Geneticists can look for individual genes in a patient to check whether the sequence of DNA bases is as expected, based on a reference genome. If there are differences in the sequence this may indicate that the gene is not providing the correct instructions and that the gene product is not functioning as it should. One way to do this is by sequencing the ‘exome’ of a patient, the portion of a genome that contains only the ‘protein-coding regions’ or the genes that provide the instructions to make proteins (these are important because proteins enable cells to function). This is known as Whole Exome Sequencing (WES).

We have a copy of our entire genome in almost every cell of our body. In order to fit within each cell, the DNA that makes up our genome is tightly coiled and organised into structures known as chromosomes. Humans generally have 46 chromosomes, made up of 23 pairs of chromosomes.

Babies inherit half of their genetic material from each of their parents – one copy of each pair of chromosomes. If a parent has a genetic disorder, this may be passed onto their child. The way a genetic condition is inherited varies, depending on several biological factors. Several family members can be affected by the same genetic disorder, over generations. This means that discoveries about one person’s genome can have implications for their relatives – even if they don’t know each other.

You may have heard the terms genetics and genomics, and wondered if they mean the same thing. The graphic below summarises the differences between genomics and genetics.

Source: NHS Genomics Education Programme, England

For more on the fundamental biology of genomics, see YourGenome website from Wellcome Connecting Science.

For more on the Human Genome Project video from 2018, (duration 7mins) showing how the multidisciplinary international collaborative team was formed, and touches on the importance of ethics and law as integral to the study of genomes.

What’s unique about genomics?

It can be argued that the field of genomics is fundamentally different from other branches of medicine. Genomics requires the collection and analysis of huge amounts of data about an individual person, which can be used for different purposes over the course of their life. For example, this data might initially be used to diagnose a health condition which is currently affecting a patient, but the genome can later be revisited to find out more about their likelihood of developing some chronic conditions (technically known as their ‘genetic predisposition’ to such conditions), or to find out whether they would benefit from receiving a particular drug.

The field is evolving rapidly and it is clear that in the coming decade, new analytical tools will be developed to look at different aspects of our genomes. The long term value of genomic data, and the uncertainty about future uses, mean that trust between patients or participants and the data controllers is of even greater importance than in other branches of medicine.

For the terms used in this course, we have provided a Glossary to help you, which can be found here.

In the next step, we’ll explore some of the main uses of genomic data.

Reflection questions

How would you feel if whole genome or exome sequencing was offered to you? What questions would be on your mind? What information would you want to have before making your decision?