While Trisomy 21 is generally known by the public as Down’s Syndrome, there is another condition called trisomy 18 that has gained attention in recent weeks.
“Trisomy 18 is a genetic disorder in which a person has a third copy of material from chromosome 18, instead of the usual two copies.”
Beautiful little Bella Santorum, President Rick Santorum’s daughter, has trisomy 18. Issues with her health have brought trisomy 18 to the public eye, as Rick Santorum had to miss some campaigning days to be with his daughter. Though the prognosis of trisomy 18 syndrome still has half of all infants not surviving, the number of children living to teenage years has shown improvement.
Causes, incidence, and risk factors
Trisomy 18 is a relatively common syndrome. It is three times more common in girls than boys. The syndrome is caused by the presence of extra material from chromosome 18. The extra material interferes with normal development.
Signs and tests
Examination of the pregnant woman may show an unusually large uterus and extra amniotic fluid. An unusually small placenta may be seen when the baby is born.
Other signs include:
- Hole, split, or cleft in the iris (coloboma)
- Separation between the left and right side of the rectus abdominis muscle (diastasis recti)
- Umbilical hernia or inguinal hernia
There are often signs of congenital heart disease, such as:
Tests may also show kidney problems, including:
Treatment of children with Trisomy 18 is planned on a case-by-case basis. Which treatments are used depends on the patient’s individual condition.
Half of infants with this condition do not survive beyond the first week of life. Some children have survived to the teenage years, but with serious medical and developmental problems.
Complications depend on the specific defects and symptoms.