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. Diagnosis
Ultrasound can increase suspicion for the condition, which can be confirmed by CVS or amniocentesis.Levels of PAPP-A, AFP, uE3, free β-hCG, all of which are generally decreased during pregnancy. Prognosis
About 95% of pregnancies that are affected do not result in a live birth. Major causes of death include apnea and heart abnormalities. It is impossible to predict an exact prognosis during pregnancy or the neonatal period. Half of the live infants do not survive beyond the first week of life. The median lifespan is five to 15 days. About 8–12% of infants survive longer than 1 year. One percent of children live to age 10. However, these estimates may be pessimistic; a retrospective Canadian study of 254 children with trisomy 18 demonstrated ten-year survival of 9.8%, and another found that 68.6% of children with surgical intervention survived infancy. Epidemiology
Edwards syndrome occurs in about one in 5,000 live births, but more conceptions are affected by the syndrome because the majority of those diagnosed with the condition prenatally will not survive to birth. Although women in their 20s and early 30s may conceive babies with Edwards syndrome, the risk of conceiving a child with it increases with a womans age. The average maternal age for conceiving a child with this disorder is 32+1⁄2.
History
Edwards syndrome was first identified by John Hilton Edwards in 1960, although he originally believed it to be caused by a trisomy of chromosome 17. Klaus Patau and Eeva Therman reported another two cases shortly thereafter. They identified the extra chromosome as being part of what Pataus lab called "group E", containing chromosomes 16, 17, and 18, but were unable to determine which chromosome was responsible at the time. Analyzing 5 more cases, they were able to determine that the extra chromosome was in fact chromosome 18. See also
18q deletion syndrome

References
External links

Edwards syndrome at Curlie
Perinatal Hospice Care - Preparing for birth and death"
Humpath #5389