Huntington's disease is the first completely dominant human genetic disease discovered by humans. After reaching the middle age, the sick people will gradually begin to lose their balance, gradually become unable to take care of themselves, and finally die prematurely. The decline in abilities first manifested itself in the beginning of a slight problem with intelligence. After that, the extremities began to tremble, and finally there was deep depression, with occasional hallucinations and delusions. There is no way to “appeal” for this disease: the disease cannot be cured. However, patients with this disease must be tortured for 15 to 25 years before they die.

 

In the late 1970s, a doctor named Milton Wexler was determined to find the genes of Huntington's disease. The doctor's wife and her three brothers have this disease. Wechsler's daughter, Nancy, knows that she has 50% of the possible pathogenic mutations. She is as enchanted as she wants to find the gene. Someone persuaded her: Or forget that such a gene may not be found. Finding this gene is like finding a needle in a haystack that is as big as the United States. She should wait a few years and wait for technological progress. May be when the gene is found. "But," she wrote, "If you have Huntington's disease, you don't have time." After seeing a report from Venezuela's doctor Amirico Negrit, she flew to Venezuela in 1979. The three villages on the lakeside in Maracaibo.

 

There is a very large family in this area, and the incidence of Huntington's disease is high in the family. According to stories circulating among family members, the disease came from a sailor in the 18th century. Wechsler successfully traced their family history back to a woman named Maria Conquest in the early 19th century. She is a prolific woman and she has 11,000 people in her eight generations. In 1981, there were still 9,000 people alive. During the visit to Wechsler, 371 of them had Huntington's disease. In addition, 3,600 people are more than a quarter more likely to develop the disease. Because at least one of their grandparents had Huntington's disease.

 

Wexler has the courage of Superman. She herself may have a mutation in her illness. “It's heartbreaking to watch these happy children,” she writes. “Despite poverty, though I can’t read, even though the boys are riding boats, fishing on the rolling lakes, they’re tired and dangerous, albeit so small. The girls are required to perform housework and take care of sick parents. Although ruthless diseases have taken away their parents, grandparents, aunts, uncles, cousins, and cousins, they still hope to live happily and heartily - - Until the disease hits."

 

Wexler began to pick up the needle in the haystack. In the first step, she collected blood samples of 500 people. "Hot, bloody days." Then she sent blood samples to Jim Cosella's laboratory in Boston. He began to look for the causal genes by testing genetic markers: Random selection of some DNA fragments may be the same as normal DNA, or it may be different. Good luck smiled at him. By the end of 1983, he not only isolated a marker that was close to the pathogenic gene, but also determined that it was on the top of the short arm of chromosome 4. “This work is extremely hard work,” said Wexler’s tone as a Victorian explorer: “The environment at the top of the four is extremely dangerous. In the past eight years, we were like climbing Everest.