Health Bulletin

Genetic advances in Down's syndrome

Scientists in the United States say they have moved a step closer to being able to treat disorders caused by an extra chromosome. They have 'switched off' the chromosome that causes the symptoms of Down's syndrome in human cells in the lab.

The research, published in Nature, could one day lead to new medical treatments for the condition. Future work may be of real benefit to people with Down's syndrome, said the United Kingdom Down's Syndrome Association.

Humans are born with 23 pairs of chromosomes, including two sex chromosomes, making a total of 46 in each cell. People with Down's syndrome have three - rather than two - copies of chromosome 21. This causes symptoms such as learning disabilities and early-onset Alzheimer's disease, as well as a greater risk of blood disorders and heart defects.

Gene therapy, which uses genes to treat illnesses, has been attempted for problems caused by a single defective gene. But until now, the idea of being able to silence the effects of a whole chromosome had appeared beyond the realms of possibility, even in the lab.

Now scientists at the University of Massachusetts Medical School have shown that, in theory, this might be possible but would take decades of research. A team led by Dr Jeanne Lawrence inserted a gene called XIST into the stem cells of a person with Down's syndrome grown in the lab.

The gene plays a role in normal cell development by switching off one of the two X chromosomes present in female embryos, ensuring daughters avoid a double dose of X chromosome genes.

The experiments showed that the gene was able to silence the extra copy of chromosome 21, helping correct unusual patterns of growth in the cells.

Commenting on the study, Carol Boys, chief executive of the Down's Syndrome Association, said it was exciting new research from a very well-respected team.

"The findings could have serious implications for future work that may be of real benefit to people with Down's syndrome," she said.

"We are a very long way from understanding how these findings might translate into clinical applications but it could be that they will be of great assistance in the search for conventional treatments for some of the health conditions that affect people with Down's syndrome."

Intelligent knife 'sniffs' out cancer

An 'intelligent' knife that can sniff out tumours to improve cancer surgery has been developed by scientists. The Imperial College London team hopes to overcome the dangerous and common problem of leaving bits of the tumour in a patient, which can then regrow.

Early results in the journal Science Translational Medicine showed the 'iKnife' could accurately identify cancerous tissue on the spot. It is now being tested in clinical trials to see if it saves lives.

The team modified a surgical knife that uses heat to cut through tissue. It is already used in hospitals around the world, but the surgeons can now analyse the smoke given off when the hot blade burns through tissue. The smoke is sucked into a high-tech 'nose' called a mass spectrometer. It detects the subtle differences between the smoke of cancerous and healthy tissue. This information is available to the surgeon within seconds.

Tests on 91 patients showed that the knife could accurately tell what type of tissue it was cutting and if it was cancerous.

Dr Zoltan Takats, who invented the system at Imperial, said: "These results provide compelling evidence that the iKnife can be applied in a wide range of cancer surgery procedures. It provides a result almost instantly, allowing surgeons to carry out procedures with a level of accuracy that hasn't been possible before. We believe it has the potential to reduce tumour recurrence rates and enable more patients to survive."

Trials are now taking place at three hospitals in London - St Mary's, Hammersmith and Charing Cross.

Gaining just a few pounds can lead to heart failure

A new study published in PLOS Medicine noted that just a one-unit increase in your body mass index (BMI) - only a seven-pound gain for a 5'9", 180-pound man - increases the risk of congestive heart failure by about 20 per cent.

Scientists analysed the health records of nearly 200,000 adults, paying close attention to people's BMI and fat mass and obesity-associated (FTO) gene, which regulates appetite. As in previous studies, subjects with certain variants of the gene had a higher BMI than those without them, but people with the variants also had a great risk of heart failure, which hasn't been shown before.

"The FTO variants increase BMI, which causes heart failure through effects on blood pressure, insulin resistance, and lipid levels as well as increased workload on the heart," says study co-author Tove Fall, PhD, of Uppsala University in Sweden.

Fall says it's your actual weight, and not so much your FTO variant, that's dangerous.

"Most people should aim to have a BMI that's less than 25 throughout life, regardless of genotype," he says.

According to a study in PLOS ONE, regular physical activity such as taking a brisk walk can cut your genetic tendency toward obesity by about 40 per cent, which can keep your heart healthy for years to come.