SCIENTISTS combing the human genome have discovered ten common genetic mutations that boost the risk of sudden cardiac arrest by subtly disrupting the heart beat, two studies released on Sunday reported. The findings shed light on the cause of the irregular rhythms that often underlie severe heart problems, and could point to new treatments, said the study, published in Nature Genetics. Heart disease is the number one killer worldwide, claiming upward of 17 million lives every year, according to the World Health Organization. Smoking, obesity and high cholesterol are common risk factors, but genes can be a critical factor too....