What genes have we found?
The first gene we found was the leptin gene in 1997. Children with a problem in the leptin gene put on weight very quickly and at a very early age.
The children are always hungry, never feel full and will seek out and ask for food even after they have just eaten. The reason for this continual drive to eat is because the children are lacking the hormone leptin which sends messages to the brain to tell us to stop eating because we are full. For these children, it has been possible to treat them with daily injections of the hormone leptin. The children are now normal weight, and it has also reversed a number of other problems that can be caused by the lack of leptin.
Leptin deficiency is very rare. We have now identified 11 other genes that can cause severe weight gain and we expect to find more with the new technologies that are now available to us. You will be able to read more about the other genes that we have found in our Patient Information pages.
We would, however, like to tell you a little bit about one of these genes called Melanocortin-4-Receptor (MC4R) because it is the commonest cause of severe weight problems in children. Many families with MC4R gene problems have very kindly come to Cambridge to help us with our studies and with their help we have learnt a lot about this gene. We know that the MC4R gene is involved in the same pathway in the brain as leptin, so children often feel hungry all the time. Children (and adults) are often very tall, and tests of body composition show an increase in bone and muscle mass compared to patients without this gene problem. We have also found that patients with an MC4R problem do not burn up the calories from food efficiently. One of the most important findings was that the MC4R gene is also involved in controlling blood pressure, something that will often be high in people that are overweight. We found that many of our MC4R patients had relatively normal blood pressures and we are looking into what this means for the heart.
For many of the gene problems that we have identified, including MC4R, there is no obvious treatment available immediately. In fact, finding the gene is the first step to understanding why someone is gaining weight and therefore finding the right treatment. This can take some time but the more information we can gain from the tests that we do, the better our knowledge of how a particular gene works or has stopped working. It can take a long time but we will keep you updated on all of the work we are doing through our website.