Why do some people _ when they drink alcohol? This effect is a common reaction to alcohol among East Asians. It affects about 36 percent of Japanese, Chinese and Koreans. For many, even a small amount of alcohol can cause unpleasant effects. Most commonly, their face, neck and sometimes their whole body turn red. People might also feel uncomfortable and sick to their stomach. They might experience a burning sensation, increased heart rate, shortness of breath and headaches. The cause is a genetic difference that they are born with called an ALDH2 deficiency  . It prevents their bodies from treating alcohol the way other people do. But the effects might be more serious than just a red face. Researchers warn of a link between this condition and an increased risk of cancer of the esophagus   from drinking alcohol. The more alcohol people with this deficiency drink, the greater their risk is. In Japan and South Korea, for example, many people have the deficiency but still drink heavily. Researchers found that these drinkers develop a form of esophageal cancer six to ten times more often than those without the deficiency. Esophageal cancer is one of the deadliest cancers. It can be treated when found early, but once it grows the chances of survival drop sharply. The researchers estimate that at least five hundred forty million people have the deficiency, about eight percent of the world's population. Philip Brooks is a researcher at the National Institute in the United States. He says it is important to educate people about the link between the alcohol flushing effect and esophageal cancer. He says doctors should ask East Asian patients about their experiences with facial flushing after drinking alcohol. Those with a history of it should be advised to limit their alcohol use. They should also be warned that cigarette smoking works with the alcohol in a way that further increases the risk of esophageal cancer. We can infer from the passage that   _  .
the ALDH2 deficiency may be passed on from generation to generation about 36 percent of Japanese, Chinese and Koreans are heavy drinkers unpleasant effects occur only when people with this deficiency drink a lot only some East Asians have the ALDH2 deficiency