Genes linked to being right- or left-handed identified

Sep. 12, 2013 — A genetic study has identified a biological process that influences whether we are right handed or left handed.

Scientists at the Universities of Oxford, St Andrews, Bristol and the Max Plank Institute in Nijmegen, the Netherlands, found correlations between handedness and a network of genes involved in establishing left-right asymmetry in developing embryos.

'The genes are involved in the biological process through which an early embryo moves on from being a round ball of cells and becomes a growing organism with an established left and right side,' explained first author William Brandler, a PhD student in the MRC Functional Genomics Unit at Oxford University.

The researchers suggest that the genes may also help establish left-right differences in the brain, which in turn influences handedness.

They report their findings in the open-access journal PLOS Genetics.

Humans are the only species to show such a strong bias in handedness, with around 90% of people being right-handed. The cause of this bias remains largely a mystery.

The researchers, led by Dr Silvia Paracchini at the University of St Andrews, were interested in understanding which genes might have an influence on handedness, in order to gain an insight into the causes and evolution of handedness.

The team carried out a genome-wide association study to identify any common gene variants that might correlate with which hand people prefer using.

The most strongly associated, statistically significant variant with handedness is located in the gene PCSK6, which is involved in the early establishment of left and right in the growing embryo.

The researchers then made full use of knowledge from previous studies of what PCSK6 and similar genes do in mice to reveal more about the biological processes involved.

Disrupting PCSK6 in mice causes 'left-right asymmetry' defects, such as abnormal positioning of organs in the body. They might have a heart and stomach on the right and their liver on the left, for example.

The researchers found that variants in other genes known to cause left-right defects when disrupted in mice were more likely to be associated with relative hand skill than you would expect by chance.

While the team has identified a role for genes involved in establishing left from right in embryo development, William Brandler cautioned that these results do not completely explain the variation in handedness seen among humans. He said: 'As with all aspects of human behaviour, nature and nurture go hand-in-hand. The development of handedness derives from a mixture of genes, environment, and cultural pressure to conform to right-handedness.'

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Statins being overprescribed for kidney disease patients

Sep. 10, 2013 — A new analysis concludes that large numbers of patients in advanced stages of kidney disease are inappropriately being prescribed statins to lower their cholesterol -- drugs that offer them no benefit and may increase other health risks such as diabetes, dementia or muscle pain.

The findings, which were published in the American Journal of Cardiovascular Drugs as a review of multiple studies, raise serious questions about the value of cholesterol-lowering therapies in kidney disease.

The issue is important, the researchers say, because the incidence of chronic kidney disease is rising in the United States at what they called "an alarming rate." Also, kidney disease patients are 23 times more likely to get cardiovascular disease, and for them it's the leading cause of death.

But for these patients, the frequent decision to prescribe statin drugs to lower cholesterol in order to reduce the risk of cardiovascular disease is not supported by the wider body of research, experts say.

"There is very little benefit to statin drugs for patients in the early stages of kidney disease, and no benefit or possible toxicity for patients in later stages," said Ali Olyaei, a professor of pharmacotherapy in the College of Pharmacy at Oregon State University, and lead author on the new report.

"I believe the evidence shows that the majority of people with chronic kidney disease are taking statins inappropriately," Olyaei said. "They may help a little in early-stage disease, but those people are not the ones who generally die from cardiovascular diseases. And by the end stages the risks outweigh any benefit. More drugs are not always better."

Some of the particular risks posed by statin use, especially at higher doses, include severe muscle pain known as rhabdomyolysis, an increase in dementia and a significant increase in the risk of developing diabetes. The body of research also shows that statins do nothing to slow the progression of kidney disease, contrary to some reports that it might.

The impetus to use statin drugs -- some of the most widely prescribed medications in the world to lower cholesterol -- is obvious in end-stage kidney disease, because those patients have a mortality rate from coronary heart disease 15 times that of the general population. Unfortunately, evidence shows the drugs do not help prevent mortality in that situation. There is also no proven efficacy of the value of statins in patients using dialysis, researchers said.

If statins are prescribed in early-stage kidney disease, the study concluded that low dosages are more appropriate.

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