Trisomy 18 Pictures

Trisomy 18 Pictures

Edwards syndrome (also known as Trisomy 18 (T18) or Trisomy E) is a genetic disorder caused by the presence of all or part of an extra 18th chromosome. It is named after John H. Edwards, who first described the syndrome in 1960. It is the second most common autosomal trisomy, after Down syndrome, that carries to term. Trisomy 18 (47,XX,+18) is caused by a meiotic nondisjunction event. With nondisjunction, a gamete (i.e., a sperm or egg cell) is produced with an extra copy of chromosome 18; the gamete thus has 24 chromosomes. When combined with a normal gamete from the other parent, the embryo has 47 chromosomes, with three copies of chromosome 18. A small percentage of cases occur when only some of the body's cells have an extra copy of chromosome 18, resulting in a mixed population of cells with a differing number of chromosomes. Such cases are sometimes called mosaic Edwards syndrome. Very rarely, a piece of chromosome 18 becomes attached to another chromosome (translocated) before or after conception. Affected individuals have two copies of chromosome 18 plus extra material from chromosome 18 attached to another chromosome. With a translocation, a person has a partial trisomy for chromosome 18, and the abnormalities are often less severe than for the typical Edwards syndrome.

Trisomy 18 Pictures

Trisomy 18 Pictures

Trisomy 18 Pictures

Trisomy 18 Pictures

Trisomy 18 Pictures

Trisomy 18 Pictures

Trisomy 18 Pictures

Trisomy 18 Pictures

Trisomy 18 Pictures