The Human Genome Project was an international research project, completed in 2003. Scientists worked out the order of the bases in human DNA, which is about 3 billion base pairs long. They identified and located all the human genes, around 20 000 of them.
This has many potential uses in medicine. Researchers can find the alleles that cause inherited disorders, so people can be tested to find out if they carry them or are at risk. Knowing a person's genotype can also let doctors choose the drug and dose most likely to work, which is called personalised medicine. It also helps scientists to research new treatments, including ways of replacing faulty genes.
There are drawbacks too. Genetic test results are private information, and there is a worry that insurers or employers might use them unfairly. Some people may feel anxious about learning they are at risk of a disease that cannot be treated. These are ethical concerns.