Continuing Chapter 4’s discussion of Down syndrome and conditions associated with it, this section covers the remaining common internal conditions associated with Down syndrome. (BTW: as the caption describes the photo above, my daughter is enrolled in the Allied Health certificate program at her high school. She has loved her classes on medical terminology, emergency procedures, and sports medicine. On her own, she selected The Atlas of the Human Body while at Barnes & Noble and enjoys transcribing the chapters into a notebook).
Down syndrome & the heart
Cardiac malformations are another condition that is common among individuals with Down syndrome. Juliet was born with two heart murmurs—holes in her heart—which closed naturally as she grew (my older brother also had a heart murmur that closed). But, of babies born with Down syndrome, about 50% will have some degree of a heart condition and of these, about 50% will need surgery. Put another way, about 25% of all children born with Down syndrome will need some form of cardiac surgery. These surgeries range in complexity, but common repairs involve restructuring the atrioventricular canal, as some of these children are born without the four chambers of their heart separated. The most intense surgical repair is when a child is born with hypoplastic left heart syndrome, requiring the surgical formation of the left ventricle, the largest chamber of the heart.
Among parents of children with Down syndrome, there is a bit of gallows humor or “gimp pride” that they embrace as a way of coping with the stress of having a baby undergo open-heart surgery. At get-togethers, occasionally you’ll hear parents refer to their child as a “zipper baby,” for the scar running up the center of their child’s chest. It is often the situation that when a child with Down syndrome is born with one of these life-threatening conditions that will require surgery, it is the surgical condition that is the focus for the parents; only after the child’s surgery is performed and the child is expected to recover does the focus then shift to the fact that the child also has Down syndrome.
Down syndrome & life expectancy
While there are many contributing factors—de-institutionalization, early intervention therapy, inclusive education—the improvement in cardiac surgical procedures and their success rates is likely the single greatest reason that the average age of individuals with Down syndrome has skyrocketed since the 1980’s.
At the turn of the 20th Century, the average life expectancy for a child with Down syndrome was just nine years old. As the 1980’s approached, that average had risen to be in the mid-20’s. Since the turn of the 21st Century, the routinely quoted average life expectancy is in the 50’s and 60’s, with that average continuing to rise. This dramatic increase from single digits to a near typical average lifespan in just 100 years is due to many if not most cardiac surgeries having a 90% success rate. A century ago, when these procedures had not even been developed, almost 25% of the children born with Down syndrome would die an early death. Now, these children can look forward to the prospect of a long and full life.
Unfortunately, there is a caveat to the rise in the average life expectancy. Not every child born with Down syndrome can expect such a long life. Sadly, the numbers just quoted apply only if the child is born with Down syndrome and also happens to be Caucasian. The average life expectancy for children with Down syndrome who are African-American is a fraction of the current life expectancy—being closer to what the life expectancy was in the 1980’s. The reasons for this disparity and injustice tracks the disparity in equality between the two races in the United States in general: levels of poverty, single-family homes, access to adequate healthcare, work schedules flexibility to allow for therapies and doctor visits, and on and on.
Down syndrome & the reproductive system
Finishing the internal system-effects of Down syndrome brings us to the reproductive system. For males, sterility is almost universal; for females, about 50% will be fertile. For both, the one developmental milestone children with Down syndrome are not delayed in is puberty. Whereas walking, talking, and other milestones usually come later than for other children, the release of hormones in adolescence is on the same timetable as for all other children.
As we just covered the racial injustice in the disparity in life expectancy, there is also an injustice regarding sex and individuals with Down syndrome. Whereas a small minority of boys without Down syndrome or other IDD will be victims of sexual abuse, that percentage is much higher for boys, and men, with Down syndrome. For women, it’s even worse. Whereas most women, tragically, are at risk for sexual assault at some point in their lives, that risk is close to 85% for women with developmental disabilities. One of my goals is for Juliet to be in that slim 15% minority of women with Down syndrome who avoid being a victim of sexual assault.
Down syndrome & leukemia
Finishing out the physical impact of Down syndrome, which is not to say this has been a comprehensive, exhaustive list, but a list of those aspects that medical professionals typically highlight, there are two diseases that those with Down syndrome are at an increased risk for: leukemia and Alzheimer’s.
Children with Down syndrome have an increased risk, as compared to the general population, for developing leukemia, but the risk remains what the AAP guidelines describe as “rare,” a one-percent chance. Nevertheless, it is a condition that medical professionals often mention, if not in counseling expectant parents, then as a reason to justify prenatal testing—the logic being that since children with Down syndrome have a slighter higher risk for leukemia, parents should be advised they have the option of terminating their pregnancies to avoid this risk. Of course, that reasoning would also support noting that individuals with Down syndrome are resistant to developing hard cell tumors, with, as an example, breast cancer being incredibly rare, and therefore an offsetting reason to the risk of developing leukemia.
The resistance to hard cell tumors prompted researchers to investigate what genes on the 21st Chromosome may, by being overexpressed, result in resistance to cancer. What they discovered is a gene that in individuals with just two pairs of 21st Chromosomes, i.e. the general population, is an accelerant for tumor growth. Counterintuitively, when that gene is overexpressed, its effect is the opposite, resulting in resistance to hard cell cancer tumors. As Dr. Roger Reeves, the lead researcher, explained,
If there were no such thing as Down syndrome, we probably wouldn’t have found this because it wouldn’t make a lot of sense to take these oncogenes that we thought were genes that cause cancer and try to express them at high levels to try to prevent cancer. But that’s what happens.
Down syndrome & Alzheimer’s
The other disease that happens with near universality for individuals with Down syndrome is Alzheimer’s. My father’s father suffered from Alzheimer’s disease for the last decade of his life. Instead of the sweet, loving man who liked to make rhymes with my name (“Mark plays in the park at dark”), he slowly began to forget things, then people, then his grandchildren, his sons, until he only, sometimes, recognized his wife. Instead of being loving, he would lash out violently in frustration. He was a body that kept living but stripped of a mind. This is the fate currently that many individuals with Down syndrome will suffer if they reach the average life expectancy. But, then I learned something that may provide some hope.
It is true that essentially all people with Down syndrome will have the symptoms of Alzheimer’s disease in a physical sense. All people with Down syndrome will develop the plaques associated with Alzheimer’s disease on their brains, with most developing these plaques earlier than other people. However, despite all having the plaques of Alzheimer’s, only as many as 50% will actually manifest the disease symptoms of dementia. It is for this reason that much of the National Institutes of Health grants for Down syndrome research have been awarded for research into possible genetic treatments for Alzheimer’s that may apply to all. The hypothesis is similar to that of hard cell tumors: what is it on the 21st Chromosome when it is overexpressed that may deter the disease symptoms of Alzheimer’s from manifesting?
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