What is Trisomy 18? An explanation of Rick Santorum's Daughter's Condition

For those who follow politics, you may have heard Republican presidential hopeful talk about his daughter, Isabllea (Bella), and how he never expected her to live to her first birthday but that she is now three years old. On Sunday, it was announced that Santorum had to cancel some planned appearances because his daughter was hospitalized at the Children’s Hospital in Philadelphia for double pneumonia (pneumonia in both lungs).

What is not often mentioned on television is what condition his daughter is actually suffering from and why it is so serious.

The name of the condition that Bella suffers from is a genetic disorder called trisomy 18 (also known as Edward’s syndrome). To understand trisomy 18, it is helpful to understand the importance of the word “trisomy.” Trisomy is when there is an extra set of chromosomes so that there are three chromosomes of a certain number instead of the usual two. This is where the word “trisomy” comes from since “tri” mean “three.” Chromsomes are structures that contain genes. Genes are units of material contained in a person's cells that contain coded instructions for how certain bodily characteristics will develop. Each person normally has 23 pairs of chromosomes, meaning that there are 46 chromosomes in total. A person with trisomy has 47 chromosomes, since there is one extra chromosome. One of each pair of chromosomes is inherited from the mother and one of each pair is inherited from the father.

Conditions in which there is an extra chromosome are medically defined based on where the extra chromosome is. For example, the most common trisomy is trisomy 21 (also known as Down’s syndrome) because there is an extra 21st chromosome. In trisomy 18 (Edwards syndrome), the 2nd most common trisomy, there is the presence of all or part of an extra 18th chromosome. The condition was named after John H. Edwards (not the former Democratic presidential candidate) who first described the condition in 1960.

Like Bella, about 80% of children affected by trisomy 18 are females. The older the mother at the time of conception, the greater the risk of trisomy 18. Santorum’s wife was 48 when she gave birth to Bella, well past the recommended age for child conception. About 1 in 6,000 live births have a diagnosis of trisomy 18. The average age of mother’s who give birth to children with trisomy 18 is 32.5.

The reason why trisomy 18 is so serious and often deadly is because it causes damage to the heart, kidneys, intestines (which can protrude outside the body), and/or other internal organs. Other problems can include but are not limited to overlapping fingers, restricted growth, an abnormally small head (microcephaly), webbing of the 2nd and 3rd toes, an upturned nose, narrow eyelid folds, underdeveloped thumbs and nails, clenched hands, low-set and malformed ears, mental retardation, widely spaced eyes, droopy eyelids, difficulties breathing, eating, and drinking. In males, there can be undescended testicles.

Most fetuses with this condition die before birth.  Common causes of death are heart damage and respiratory problems. Half of children born with this condition do not live past the first week. About 8% live longer than one year. Only 1% will live to age 10, although these are the less severe cases. Fortunately, after being in and out of the hospital for most of the first year of her life, Bella has not been hospitalized since this most recent event and is reportedly improving.

For those wishing to make a donation to the Trisomy 18 Foundation, you can do so at this link.

Suggested reading: I Am Not a Syndrome - My Name is Simon