Trisomy Awareness: Support Organization For Trisomy (Trisomy.org)
Trisomy18.org · Trisomy 13 Life · Donate
Trisomy is a genetic disorder caused by three copies of a chromosome instead of the usual two.
After Trisomy 21, commonly known as Down syndrome, Trisomy 18 (Edwards syndrome) and Trisomy 13 (Patau syndrome) occur most frequently. Congenital malformations, serious developmental and motor delays, and a high incidence of mortality are present in all three trisomies. But in Trisomies 13 and 18, the delays are usually greater, and the prognosis includes a much shorter life span.
However, trisomies are not universally lethal, as sometimes described: 5-8% of infants live past their first birthday often without extraordinary measures. And, once a child’s age is greater than a year there is a 60% chance to live beyond age 5 years.
- Statistically, the incidence of trisomy 21 (Down syndrome) is about 1 in 1,000 live births; for Trisomy 18, this is about 1 in 5,000 live births, and for Trisomy 13, about 1 in 10,000 to 21,700 live births (the median figure being 1 in 16,000 live births).
- The risk of having a baby with a trisomy condition increases with the age of the mother, especially after her early 30s.
- However, there are no precise figures on how common trisomy conditions are, as some parents elect not to carry a fetus that has been diagnosed as such to term, an issue of strong contention within the pro-choice, anti-choice, and disability advocacy communities.