There are many causes of genetic defects and an even longer list of the different types. Fortunately, scientists have the capability to research, find out potential causes, and determine if there are cures. Research has shown that 1 out of every 3-4 fertilized eggs are chromosomally abnormal. Trisomy 18, or Edwards's syndrome, is a genetic disorder that affects embryos from the moment of conception. This disease is not causes by the actions of the mother or father, but by the chromosomes presented during fertilization.
Trisomy 18 is a chromosomal condition associated with abnormalities in many parts of the body when a third copy of chromosome 18 is present ("Trisomy 18."). It is the second most common trisomy disorder ("What Is Trisomy 18?"). It is nondisjunction occurrence, which is an error in cell division that results in a reproductive cell with an abnormal number of chromosomes ("Trisomy 18."). Only 1 in 5,000 infants are diagnosed and survive until birth; many individuals die before birth or within the first month. 50% of babies that are carried to term will be stillborn, with boys at a higher stillbirth rate than girls ("What Is Trisomy 18?"). Only 5-10% that survives birth lives past their first year, but often they have severe intellectual disabilities ("Trisomy 18."). There are a small number of adults (usually girls) that are living into their 20s and 30s, although with significant developmental delays that do not allow them to live independently without assisted caregiving ("What Is Trisomy 18?"). As with most embryonic genetic defects, the chance of developing this condition increases as the mother ages ("Trisomy 18.").
Scientist have discovered 5 different chromosomal variations. The first one is chromosome 18p. This chromosome has a missing piece from the short arm of chromosome 18. The second variation is chromosome 18q, which is missing a piece from the long arm. In this case if the missing piece is located close to the centromere it is proximal 18q.
