Detailed Instructions: In this task, you are given a text of many news articles seperated by special token "|||||". Your task is to summarize them.
Q: The X and Y chromosomes, with the smaller Y chromosome to the right. 
  
 Add another troubling side effect to the list of health issues caused by cigarettes: Smoking may cause the Y chromosome to disappear from men's blood cells. 
  
 A new study finds that men who smoke lose the Y chromosome in blood cells more frequently than nonsmokers — and the heavier their cigarette use is, the fewer Y chromosomes they have. 
  
 This Y chromosome loss could explain why male smokers are at higher risk of cancer than female smokers, the researchers said in their study, published today (Dec. 4) in the journal Science. 
  
 "The cells that lose the Y chromosome … They don't die," said study co-author Lars Forsberg, of the Department of Immunology, Genetics and Pathology at Uppsala University in Sweden. "But we think that they would have a disrupted biological function." 
  
 More specifically, the immune cells in the blood that are tasked with fighting cancer may be hampered without their Y chromosome, Forsberg told Live Science. [Macho Man: 10 Wild Facts About His Body] 
  
 The case of the missing Y 
  
 The Y chromosome is one of two sex-determining chromosomes in men, who have one X chromosome and one Y. (Women have two X chromosomes.) Normally, during cell division, copies of all of the chromosomes are made and sorted into the two new daughter cells. But during the complex process, chromosomes are sometimes lost, Forsberg said. 
  
 Usually, a missing chromosome would result in the death of the new cell, but cells can survive without a Y chromosome. 
  
 Scientists have known for more than 50 years that Y chromosomes can vanish, Forsberg said. Missing Y's are more common in older men than in younger men. In April, however, Forsberg and his colleagues published findings in the journal Nature Genetics revealing that the loss of the Y chromosome in the blood cells is linked with an increased risk of cancer in men. 
  
 The next task, Forsberg said, was to find out what factors lead men to lose their Y chromosomes. He and his colleagues gathered health data from a total of 6,000 men who were participating in three different ongoing epidemiological studies in Sweden. The men were questioned on factors such as exercise, blood pressure, alcohol use and smoking, and also gave blood samples, so the researchers could test the prevalence of the Y chromosome in the blood. (Because red blood cells don't carry any DNA, the results apply only to the white blood cells, or immune cells, that circulate in the blood.) 
  
 Smoking's strange side effect 
  
 The results showed that it was very common for men in the study to be missing Y chromosomes from their cells. The men in two of the studies ranged in age from 70 to 80 years old. In the first group, 12.6 percent of men were missing Y chromosomes from their blood cells; in the second group, 15.6 percent had lost the Y chromosome. 
  
 The third group of men ranged in age from 48 to 93, and only 7.5 percent were missing Y chromosomes. The results from this group highlighted the effect of age, the researchers said. Among the men age 70 and older, 15.4 percent were missing Y chromosomes, compared with 4.1 percent of men younger than 70. 
  
 With those overall numbers established, the researchers compared participants on lifestyle and health factors and found that, other than age, only smoking was linked to the loss of the Y chromosome. Smokers had between 2.4 and 4.3 times the risk of losing Y chromosomes compared with nonsmokers. 
  
 More experimental work will be necessary to prove that smoking directly causes Y chromosomes to vanish — and to pin down exactly how cigarettes may bring about this side effect. But several clues in the results strongly imply that cigarettes are the culprit. For one, the men who smoked more had lost more Y chromosomes. And among men who had stopped smoking, the levels of Y chromosome in their blood were indistinguishable from those of men who never smoked. 
  
 That last finding is particularly encouraging, Forsberg said. 
  
 "When you stop smoking, these cell clones with loss of [the] Y [chromosome] will disappear from circulation," he said. In other words, the Y disappearance is reversible. [10 Scientific Tips to Quit Smoking] 
  
 Researchers aren't sure how widespread the smoking-related loss of Y is among other cells in the body; other studies of older men have suggested that Y chromosomes may disappear in other tissues with age, Forsberg said. 
  
 Cancer link? 
  
 The loss of the Y chromosome in the blood has little to do with manliness, despite the chromosome's association with sex. 
  
 "The Y chromosome is involved in much more than sex determination and reproduction," Forsberg said. 
  
 Instead, this vanishing chromosome could be the link that explains why men have a higher risk of cancer (from smoking, and in general) than women, Forsberg said. One possibility is that the missing Y is harmless in and of itself, but acts as a canary in a coal mine, signaling that cells are being damaged by smoking and accruing mutations that can cause cancer. 
  
 But Forsberg and his team believe the story may be more complex. 
  
 "Since we study blood cells from whole blood, it's basically the immune system that we study," he said. "One of the functions of the immune system is to fight cancer throughout life." 
  
 If some of the genetic code carried on the Y chromosome helps with this cancer-fighting function, the loss of the Y in blood could make the body more susceptible to tumors, he said. Next, the researchers plan to tackle immune cell types one by one, to find out which might be most affected by a missing Y chromosome. 
  
 Follow Stephanie Pappas on Twitter. Follow us @livescience, Facebook & Google+. Original article on Live Science. ||||| A man smokes in front of a ''no smoking'' sign outside a shopping mall in Shanghai January 10, 2014. 
  
 LONDON Male smokers are three times more likely than non-smoking men to lose their Y chromosomes, according to research which may explain why men develop and die from many cancers at disproportionate rates compared to women. 
  
 In a study in the journal Science, researchers at Sweden's Uppsala University found that Y chromosomes, which are important for sex determination and sperm production, more often disappear from blood cells of smokers than those of men who have never smoked or of men who have kicked the habit. 
  
 Since only men have Y chromosomes, the finding offers a possible answer to why smoking is a greater risk factor for cancer among men than women. 
  
 "There is a correlation between a common and avoidable risk factor, that is smoking, and the most common human mutation -- loss of the Y chromosome," said Jan Dumanski, an Uppsala professor who worked on the study. 
  
 "This ... may in part explain why men in general have a shorter life span than women and why smoking is more dangerous for men." 
  
 Besides lung cancer, which is caused by smoking and is often fatal, tobacco smoking is known to be a major risk factor for a range of serious illnesses. It is the world's leading preventable cause of premature death from chronic conditions such as heart disease, strokes and high blood pressure. 
  
 Epidemiological data show male smokers have a higher risk of developing non-lung forms of cancer than women who smoke. 
  
 The team analysed data on more than 6,000 men, taking into account their ages, exercise habits, cholesterol levels, education status, alcohol intake and many other health and behavioural factors. 
  
 They discovered that in smokers, the loss of Y chromosomes appeared to be dose-dependent -- in other words, men who smoked more lost more -- and that some men who went on to quit smoking appeared to regain their Y chromosomes. 
  
 Lars Forsberg, who also worked on the study, said this suggested Y chromosome loss due to smoking might be reversible 
  
 "This discovery could be very persuasive for motivating smokers to quit," he said. 
  
 The scientists are not sure how loss of Y chromosomes in blood cells is linked with the development of cancer, although one possibility is that immune cells in blood that have lost their Y chromosome have a reduced capacity to fight cancer cells. 
  
 (Reporting by Kate Kelland; Editing by Gareth Jones) |||||
A:
Even if general appeals to one's health aren't enough to convince people to quit smoking, perhaps this new research out of Sweden will give men some pause. An Uppsala University study published yesterday in Science says that male smokers are, on average, three times more likely to lose Y chromosomes as their nonsmoking counterparts, Reuters reports. The study also found that the more men smoked, the more Y chromosomes they lost, LiveScience reports. "The cells that lose the Y chromosome … don't die," says study co-author Lars Forsberg. "But we think that they … have a disrupted biological function." Specifically, that disrupted function may mean that blood cells missing the Y's can't fight off disease, he explains—and because only men have Y chromosomes, that cell-weakening could be the link to men's higher cancer rates. The study looked at blood pressure, as well as drinking, exercising, and smoking habits, and collected blood samples of 6,000 men taking part in three separate studies in Sweden. Forsberg and his team had previously linked the loss of the Y chromosomes in blood to shorter life spans and a jump in the rate of non-blood-related cancers, so they controlled for age in this study to isolate other factors that might lead to this loss: Only smoking had a correlation. There's good news to be found from the study, though: Forsberg says that some study participants who eventually kicked the habit ended up recouping their lost Y chromosomes, suggesting the chromosome loss may be reversible. "This discovery could be very persuasive for motivating smokers to quit," he says. (Meanwhile, women have a higher risk of heart disease from smoking than men.)