Rare Genetic Diseases: Edward’s Syndrome

The trisomy on the 18th chromosome causes a genetic disorder called the Edward’s syndrome, which affects approximately one in 5,000 live births.

Edward’s syndrome is a rare genetic disorder and the second most prevalent trisomy, which is more common in girls than boys. It is caused by faulty cell division, known as meiotic disjunction. The formation of an extra chromosome happens at random amid the development of the sperm or the egg.

There are three different types of the trisomy 18. First one is called Mosaic trisomy, which was identified as the less severe form of Edward’s syndrome, because the third chromosome was not present in all of the cells. In partial trisomy, only a small part of the third chromosome was present and it was attached to either one of the two 18th chromosomes. Lastly, full trisomy represents the most severe type of Edwards syndrome, in which the whole third chromosome is present in all of the cells.

Individuals affected by this disease have severe mental and physical life-threatening disabilities. The characteristic symptoms include small lower jaw (micrognathia), heart defect, clenched fist with overlapping fingers, club foot and short sternum. Furthermore, affected individuals have small, abnormally shaped heads as well as kidney defects. They also suffer from delayed neurodevelopment and have slow growth before birth (intrauterine growth retardation).

Unfortunately, there is no known cure for Edward’s syndrome. Furthermore, the majority of the infants die shortly before or after the birth, due to the severe defects. However, some individuals survive until the age of two, and very rarely, they live into adulthood.