Alzheimer's disease, also known as Alzheimer's disease, is a kind of primary degenerative brain disability that occurs in pre-senile and senile age, that is, memory, thinking ability, analytical judgment, visual spatial recognition, emotional and other disorders without disturbance of consciousness. The most common symptom is forgetfulness. Chinese people over the age of 65 account for 8% of the total population, of which the prevalence rate of dementia is about 5%, that is, about 6 million suffer from different types of dementia, while the prevalence rate is 11.5% over the age of 75 and more than 30% over the age of 85. Cerebral degenerative diseases, cerebrovascular diseases, genetic factors, endocrine diseases, nutritional and metabolic disorders, drugs, AIDS, syphilis, brain trauma and so on may lead to Alzheimer's disease.at present, it is difficult for middle and late stage patients to obtain therapeutic effect, and early diagnosis and early treatment is the only way to delay the onset of the disease. However, there is no clear boundary between the physiology and psychology of the early patients with the disease and normal aging, so it is difficult to diagnose the patients in time. The risk of children with Alzheimer's disease was 4.3 times higher than that of the general population. Therefore, if we can detect the susceptibility genes of Alzheimer's disease as early as possible, and provide an important reference basis for the recognition and prevention of disease, we can stay away from Alzheimer's disease and spend our lives happily and healthily.
Alzheimer's disease is not normal aging, but can cause memory, computing, language and cognitive thinking and other disorders of the brain degenerative disease, the disease is a polygenic disease. Most affected by heredity.
, Three pathogenic genes specifically associated with autosomal dominant familial Alzheimer's disease are recognized: PSEN1, PSEN2 and APP. Mutations in PSEN1 and APP are associated with complete dominance, that is, if a person has a PSEN1 or APP mutation, as long as he lives an average life expectancy, he is bound to develop Alzheimer's disease in his lifetime. The mutation in PSEN2 is associated with only 95 per cent of the explicit rate, that is to say, not everyone with a PSEN2 mutation develops Alzheimer's disease. Even in the same family, the age of onset can vary from person to person for 20 years, and even the same mutations do not necessarily cause the same clinical manifestations within or between families, so care should be taken in interpreting the test results.
compared with the above three pathogenic genes, the fourth gene, APOE, has been identified as a susceptible gene for Alzheimer's disease. APOE has three subtypes, ε 2, ε 3 and ε 4. Among them, ε 2 plays a protective role against Alzheimer's disease, but ε 4 is associated with an increased risk of Alzheimer's disease, especially the risk of late-onset Alzheimer's disease. The effect of ε 4 allele on the increased risk of Alzheimer's disease is quantitative dependent. It is generally believed that carrying one ε 4 gene will increase the risk of Alzheimer's disease by 2-4 times. People with two ε 4 alleles have the highest risk of Alzheimer's disease, with an increased risk of up to 10 times. Therefore, APOE gene screening can be carried out for more older individuals who do not have a clear family history.