Facts about Human Genetics

The study of human genetics seeks to understand the role of genes in the development of disease, and how this knowledge can be used to design new therapeutics. It also looks at the genetic contribution to human nature.

The human genome consists of approximately 20,000-25,000 genes spread over 3 billion DNA base pairs. That’s a lot of genetic information, and during DNA replication there are plenty of opportunities for mistakes to occur. Some of these errors are benign and we’ll never know a thing about them. Others can have serious consequences to our health by affecting the way proteins are made. If mutations happen in germ line cells they can be passed onto the next generation.

As technology improves more and more inherited diseases can be detected by DNA testing. These tests can examine changes in a fetus's genes or they can be used to screen newborn infants. Many families with a history of a particular genetic disorder find this useful, although tests should only really be carried out after a family has had genetic counselling and professional guidance so they can interpret the results and what they might mean. Before testing takes place scientists are able to work out the probability of an individual inheriting a specific mutation based on family history. This is made possible by exploring the trait's pattern of inheritance, which derives from Gregor Mendel's laws of inheritance. Those patterns include autosomal dominant, autosomal recessive, X-linked, and Y-linked.

For many genetic disorders, such as Duchenne Muscular Dystrophy, or Fish Malodor Syndrome, the best that can be done is to manage the symptoms as best as possible, as there is currently no cure. But this is where gene therapy hopes to step in and rid us of the horrible diseases that can blight our lives. The concept is simple - replace a faulty gene with a good working copy. The reality is that it is an extremely tricky technology, and will be many years before it is a regular medical treatment.

Human genetics is also a prominent player in the debates about whether sexuality or personality traits are influenced by nature (genetics) or nurture (environment). The debate as such is perhaps a redundant one in that what is increasingly being seen is that both nature and nurture are important. What is unknown in many cases are the relative contributions of each. Are genes the biggest factor in the cause of some addictions? Does the environment make the biggest contribution as to whether an individual is homosexual?

Understanding that it is nature with nurture and how genes interact with the environment is also valuable for medical science in determining the cause and progression of diseases.

The Human Genome Project has forever revolutionised the field of human genetics. It is providing incredible amounts of new data for scientists to puzzle over in the search for cures for genetic disorders, and answers as to what makes us all tick.