Introduction: Aneuploidy or the abnormal number of chromosomes can cause various disorders such as: spontaneous abortions, developmental defects and cancer. One of the types of aneuploidy is Edward's syndrome, which is discussed in this article.
There are two important points about this syndrome. First, this syndrome is the second most common trisomy in the world after trisomy 21 or Down syndrome, and secondly, the exact mechanism of the cause of this syndrome has not yet been discovered.
In this field, many articles have been written, especially in the form of examining different patients, but however, this issue has not been examined as it should be. In this article, we try to collect the information written in previous studies and prepare the ground for further research.
Methods: In order to write this article, we first studied general and basic information on the Internet and then reviewed and studied articles in Google Scholar from 2019 until now. In the search of articles, we also used terms such as: Edward's syndrome, Edward's syndrome genetics, Edward's syndrome symptoms and Edward's syndrome treatment and the prevalence of trisomy 18.
Results: Edward's syndrome was first defined in the 1960s. This syndrome is known as the second most common trisomy, and the prevalence of this syndrome among newborns is 1/1600 to 1/1800, but due to many abortions, as well as its diagnosis and termination of pregnancy, the number of these babies has reached 1/3600. and the prevalence of Edward's syndrome in girls is 3 times that of boys.
Edward's syndrome is one of the prominent aneuploidies in the world. In this syndrome, there are 3 of chromosome 18 and it is actually a type of trisomy. In general, trisomies cause disturbances in the cell cycle, such as reducing the ability of somatic cells to reproduce.
The cause of this syndrome is either the lack of correct segregation of chromosomes during meiosis, especially from the maternal side (94%) or less commonly post zygotic nondisjunction mitosis. However, the exact mechanism of trisomy 18 is not known.
Genetically, trisomy 18 can be in the following three forms: 1) a complete extra chromosome 2) a partial trisomy (18q) 3) or a mosaic
This trisomy causes a significant increase in mortality in sufferers, so that only 5 to 10% of sufferers survive after one year of age, but on the other hand, even though this syndrome is associated with a high risk of stillbirth and fetal loss, more than 50% of patients survive for more than a week. In the past, this disease was called "incompatible with life" and special treatment methods were not prescribed for the sufferers, but temporary sedatives were prescribed by the medical community, but today, researchers of treatment methods to correct congenital anomalies (medical and surgical interventions) especially Cardiac abnormalities have been presented to increase the survival of this baby.
It is noteworthy that the prevalence of this trisomy increases with the age of the mother.
The symptoms of this syndrome include: incomplete heart, digestive defects, abnormalities of the stomach, esophagus and endocrine glands, hearing and vision disorders, kidney disorders, abnormalities of the nervous system, mental retardation, drooping ears and bent fingers.
Conclusion: Congenital abnormalities such as the topic discussed in this article impose heavy economic, social and cultural consequences on the family and society, therefore, early diagnosis and termination of pregnancy is very important. Therefore, in this article, we did a general review of this trisomy and its symptoms.
It is expected that in the future researches, methods of prevention and early diagnosis of this disorder will be worked on. Also, an important defect in this field is the reason for the occurrence of this syndrome and its exact mechanism, and also methods for treating or increasing the life span of the sufferers can be found. important and vital issues for the continuation of the research process.