Because of the gene mutation or over-expansion of CAG trinucleotide repeat sequence in the fourth chromosome DNA (deoxyribonucleic acid) matrix, brain nerve cells are degenerating continuously, and somatic cells mistakenly produce a harmful substance called Huntington protein. These abnormal protein piles up and damages some brain cells, especially those related to muscle control, leading to the gradual deterioration of the patient's nervous system, the spread of nerve impulses, dyskinesia, uncontrollable convulsions, and may develop into dementia or even death.

The main reason is gene mutation caused by family inheritance or external stimulation. As long as the genes from either parent have genetic defects, they will show symptoms. The main symptoms are: 1. Abnormal mood, become indifferent, irritable or melancholy. 2. Involuntary movements of fingers, legs, face or body. 3. Decline in intelligence, judgment, memory and cognitive ability. Generally speaking, the cause of death of patients is sudden fall or other infection complications. At present, drugs can control and slow down mood swings and exercise problems, but they can't completely cure diseases.

After 10 years of purgatory research and exploration, a multinational scientific research team claimed to have discovered the gene that caused Huntington's disease. During the period of 10, they did research in the wrong direction, tasted the pain caused by experimental failure, and finally found the long-sought goal in molecular biology.

The researchers said that now that they have mastered this gene, they can begin to study this mental illness caused by the decline of the nervous system. This disease usually affects people around the age of 30 to 40. The patient looks normal, but in fact, his body has been seriously damaged and will die in 10 to 20 years.

Huntington's disease plagues about 30,000 Americans, and another 654.38+500,000 Americans are at risk. Udi Guthrie, a well-known folk singer, is one of its victims.

In the early 1980s, people discovered the genetic clues that led to Huntington's chorea. At that time, it was in the initial stage of a new form of molecular genetics, and researchers soon encountered a series of troubles, which made the research more challenging and irresistible, and thus attracted many excellent biologists.

What interests scientists is that the gene mutation that causes this disease is the same as the gene that they saw in other diseases not long ago. It is a molecular folding reaction, and a short gene is abnormally extended and repeated.

Researchers say that a lot of work needs to be done before this mutation can be used as an accurate method to predict diseases. The discovery of pathogenic genes does not mean that a cure for this disease has been found. But this discovery provides a substantial answer to the mystery of Huntington's dance. The results of this research, published in Cell magazine, are convincing because it was discovered by Huntington's Dance Joint Research Group. This is a rare continuous scientific cooperation. The six laboratories participating in the research are located in the United States, England and Wales, and these laboratories share their research data and ideas.

Biologists everywhere, even those who have competed with this joint research group, can't help but feel happy and sincerely gratified by this discovery.

"This is a great event. I find it hard to believe that it really succeeded after so many years. This is a very important and significant discovery. " Dr Rick Mills of the University of California, San Francisco said. He also tried to isolate the gene.

Dr. David L. Nelson, a molecular geneticist at Baylor Medical College in Houston, said, "This is simply wonderful. People have always wondered why this gene can't be found. Now it's taken so long to finally find it. I am gratified and excited about this. " Dr Nelson has been studying a mental illness called fragile X syndrome, which is also caused by similar abnormal gene expansion.

Nancy S. wexler, who works at Columbia University in new york and the Genetic Diseases Foundation in Santa Monica, California, has been trying to maintain this multinational research group for many years. She has also visited villages in Venezuela many times, where many villagers suffer from Huntington's disease. When the cooperative team isolated the gene, she had just left there to investigate in South Africa. She said: "I was shocked, just like hitting a wall, and then I was ecstatic and walked around."

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Dr wexler's mother died of Huntington's disease, and the chance of her inheritance is 50%. Although there is an examination method that can accurately diagnose whether a person has the disease 10 years in advance, Wexler never talked about whether he had been examined.

The next research is to try to determine the influence of protein caused by Huntington gene copy on human body, and why the mutation of this gene will have such serious consequences.

"As far as we know, this protein is different from any known species," said Dr. Francis S. Collins of the University of Michigan. He also participated in this international cooperation.

This kind of mental illness begins to appear in infancy and adolescence, but the symptoms are not obvious. In adulthood, various symptoms will appear together: behavioral disorders, involuntary movements of various parts of the body, mental confusion, neurasthenia, and even death. Huntington's patients walk unsteadily and speak vaguely, and are often mistaken for drunkenness. Researchers suspect that some witches in Salem once suffered from this disease.

This disease is caused by a large number of deaths of nerves that maintain basic life activities in the cerebral ganglia, which is controlling people's actions and cognition.

Although this disease is rare, it has become the focus of public attention, partly because of the openness of this genetic research.

10 years ago, Dr. James P. Kossler of Massachusetts Public Hospital, who was also the head of the international cooperation team, discovered the Huntington symbol, a DNA that can show the approximate location of Huntington gene. There are 23 pairs of chromosomes in human cells, which are located in the upper part of chromosome 4.

Dr. Gossler and his partners speculated that it would be easy to find the gene of SIj, but in fact, scientists have struggled for many years to succeed, just like finding the gene that causes cell fibrosis, muscular dystrophy and neurofibroma.

Because of the particularity of Huntington's genetic model and the complexity of chromosome tip research, scientists are constantly led astray. At the tip of chromosome, the gene density is high, and there are many phenomena of gene recombination or chromosome exchange, so it is difficult to study it in depth.

Scientists say that the study of Huntington gene marks the end of the era of finding a single gene for treatment. From now on, biologists intend to concentrate on the human genome project and jointly list 100000 genes about human beings.

Finally, scientists discovered an unstable gene controlled by dangerous inflation, just as they saw in fragile X syndrome and two other hereditary mental diseases.

In Huntington gene, variation will affect the triplet within the gene, which is expressed by chemical CAG. For normal people, this gene contains 1 1 to 30 such triplets, but there are 35 to 100 or more in Huntington's disease patients. The intermittence of this molecular composition will disturb the function of protein made by genes, or produce incomplete and dysfunctional protein. In any case, the bad result is the death of brain cells.

By examining 75 Huntington's disease families, the researchers found that every patient with Huntington's disease had an unusual triplet amplification. They are further confirming that the increase of too many triplets in life will make people become victims of this disease.

If this international cooperation continues, researchers can diagnose whether people will get an incurable disease and when it will break out. Dr. Colin said that this discovery will maximize human understanding of genes.

Huntington's disease is a hereditary neurodegenerative disease. The main reason is that the Huntington gene on the fourth chromosome of the patient is mutated, resulting in a mutated protein, and protein gradually gathers in the cell to form a macromolecular group. Scientists call these water-insoluble molecular groups "inclusion bodies". Generally, patients develop symptoms in middle age and gradually lose the ability to speak, act, think and swallow. The disease will continue to develop for about 15 to 20 years until the final death, and eventually lead to the death of the patient. The genetic probability of this disease is 50%.

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1. Bile acids found in America can delay the onset of Huntington's disease.

In 2002, American researchers discovered a new clue to treat Huntington's disease. They found in experimental mice that a bile acid can effectively reduce the damage caused by this disease to brain nerve cells.

Keane of the University of Minnesota and others introduced in the Proceedings of the National Academy of Sciences that in the experiment, they chose a group of sick mice with Huntington's disease-causing genes and showed symptoms, and compared them with a group of healthy mice. The researchers first injected half of the sick mice with taurocholic acid (TUDCA), and then let the sick mice injected with this bile acid, the sick mice that did not receive the injection and the normal experimental mice participate in the maze walking test respectively. The results showed that the ability of sick mice injected with bile acid was half stronger than that of mice not injected with bile acid, and there was almost no difference with healthy mice. Brain examination also found that the number of brain cell deaths in mice injected with bile acid was significantly less than that in mice that did not receive injection.

At present, there is no effective treatment for Huntington's disease, but it can be detected whether the fetus carries the mutant gene that causes the disease before birth. If future research can prove that bile acid therapy is also suitable for human body and can prevent the death of brain nerve cells when patients are young, it will be possible to realize lifelong prevention and treatment of Huntington's disease. However, it is still far from this goal at present, and a lot of research work is needed before starting human clinical trials.

2. American scientists found that Congo red can treat Huntington's disease.

Scientists at Harvard Medical School reported in the journal Nature published on June 5438+1October 23, 2003 that Congo Red, a dye commonly used in medical experiments, can prevent some abnormal protein accumulation in the brain, thus preventing Huntington's disease.

Congo red is a common cell marker dye in medical experiments. When researchers examine brain slices of Huntington's disease patients, they usually dye them with Congo red. Congo red can adhere to abnormal proteins and clearly show the aggregation area of protein blocks.

The experiment of brain cell tissue culture conducted by scientists from Harvard Medical College shows that Congo red dye can not only attach to abnormal protein block, but also slow down the accumulation process of protein, and brain cells treated with Congo red are not easy to die. The experimental mice with Huntington's disease gene have less neurological dysfunction after receiving Congo red dye injection.

This discovery provides a new idea for the treatment of Huntington's disease, but before this method is applied to clinic, further research and improvement are needed. Congo Red is also used to mark abnormal protein in brain diseases such as Alzheimer's disease and Roitz's Felt-Jacob disease, so it may also help to prevent and treat these diseases.

3. Key protein related to Huntington's disease treatment.

Huntington's disease is caused by a mutant Huntington gene, which can have protein containing many copies of amino acids (called glutamine). Normal Huntington protein contains 10-25 glutamine sequence. However, if there are more than 36 glutamine sequences, the shape of protein will change and form a large cluster in neurons. This will kill these cells in the striatum of the brain, leading to unique loss of coordination and dementia.