New Genetic clue to common diseases
30 May 2006
Scientists have uncovered a new way by which the levels of gene expression can vary to make us fat, have high blood pressure or suffer from other conditions like asthma or diabetes.
The work by scientists at the Medical Research Council has identified a new genetic mechanism that could have wide research implications in the study of common diseases. They’ve found that some parts of human DNA, which don’t contain genes play a role in switching genes on or off and that altering these so called regulatory elements can cause disease.
The director of the MRC’s Molecular Haematology Unit, Professor Doug Higgs explained: “The human genome is made up of around three billion letters of DNA. We now know that some inherited diseases can result from a change in a single letter of DNA. About 25,000 genes are used to build an individual but they’re only a small part of our DNA. It’s not entirely clear what the rest of our DNA does. We do know that a small proportion of the remaining sequences are used to switch genes ‘on’ and ‘off’ in the right place, at the right level and at the right time in development.
“They are rather like the on/off switches on a radio. Without these controls, the radio is either silent or doesn’t work as it should. Similarly, inherited or acquired changes, known as mutations, in a gene's regulatory element may impair normal gene expression and cause human genetic disease.”
Scientists at the MHU have discovered that thalassaemia, an inherited blood disorder, can result from a change in a single letter of DNA that creates an entirely new control element where there should not be one. In the case of thalassaemia, the new switch turns the haemoglobin (red blood cell pigment) gene off when it should be on, causing the affected patient to develop anaemia.
Professor Higgs went on: “The discovery of this new mechanism could have much wider implications. Scientists know that about one in every thousand letters in the regions of DNA without genes differs between individuals. It’s likely that some of these differences may account for some of the normal variation we see between people. Importantly, in some cases, these changes may make us more likely to suffer from common diseases such as obesity, high blood pressure, diabetes and asthma.”
“It’s been a challenge to identify these important genetic variants and our research has developed an important tool for their recognition.” He added: “This is another example where, by carefully studying a relatively uncommon genetic condition, we have uncovered what may turn out to be a common way by which genes are turned on and off to cause genetic variation, including our susceptibility to common diseases.”
