Animals with down syndrome like diseases can exist in tigers, dogs, monkeys, and lions. While it is not exactly the same disease as down syndrome, it can leave the animal with similar visual and mental characteristics.
While humans are the only living creatures who can develop down syndrome, animals are able to develop a very similar disease to down syndrome. Down syndrome is unique to only human chromosomes, however, we share similar chromosomes with other animals and they can have similar mental illnesses to what humans can have.
To learn all about down syndrome and its counterpart in animals including in tigers, dogs, monkey, lions, etc., check out this guide.
My youngest sister, Cindy, has Down syndrome, and I remember my mother spending hours and hours with her, teaching her to tie her shoelaces on her own, drilling multiplication tables with Cindy, practicing piano every day with her. No one expected Cindy to get a Ph.D.! But my mom wanted her to be the best she could be, within her limits. – Amy Chua
What Is Down Syndrome?
Before we delve into animals with chromosomal problems very similar to Down Syndrome, it is important to go over what down syndrome is. Merriam – Webster dictionary (found here) define’s Down Syndrome as:
a congenital condition characterized especially by developmental delays, usually mild to moderate impairment in cognitive functioning, short stature, upward slanting eyes, a flattened nasal bridge, broad hands with short fingers, decreased muscle tone, and by trisomy of the human chromosome numbered 21 — called also trisomy 21
Down’s is not a heredity disease and in most cases, the parents have no genetic problems, that thrice 21st chromosome happens by total chance. With that being said, the risk of Down Syndrome increases after the mother turns 45 (likelihood goes up to about a 3% chance of the fetus having Down’s). This disease can be caught with prenatal screenings, and often times the fetus may be aborted depending on what the mother and father want. 1 in every 700 babies are born with Down Syndrome in the United States, and every year there are about 6,000 babies in the United States are born with Down Syndrome. The life expectancy of someone who has Down Syndrome is about 60 years old. In Europe 92% of pregnancies that test positive for their child having Down’s are terminated, however, in the United States, only 67% are terminated.
Medications have made Down Syndrome easier to handle for those affected by it, but there is no cure for Down’s. Depending on the child some kids are able to be put into a normal classroom setting while others might need to have a specialized setting for learning. The average IQ with someone with Down’s is around 60, which is the same mental ability of a 10-year-old child, but obviously, those numbers can vary based on the person.
The term “Down Syndrome” came from Dr. John Down who researched and described this illness in the 1860’s. It was not until 1959 that scientists learned that Down Syndrome came from the extra copy of the 21st chromosome. After discovering that the cause was from the extra copy of the 21st chromosome the disease was also referred to a trisomy 21 (tri meaning three).
Characteristics of Down Syndrome
Here are some of the characteristics of Down Syndrome:
- Almond-shaped eyes
- Lack of muscle tone
- White spots on the iris
- Large tongue
- Gradual hearing loss throughout life
- Flattened face
- Sleep apnea
- Heart defects
- Ear infections throughout life
There are considerably more characteristics, but these are some of the more prominent ones.
Down Syndrome in Animals
Like we said a few times, Down Syndrome is a uniquely human illness, meaning that animals cannot actually have Down Syndrome. They can, however, have other mental illnesses that closely resemblance Down Syndrome. Why can’t animals have Down’s? Well, no other animal has our chromosomal organization (even chimps who share 99% of our DNA cannot get Down’s). However, animals do have a chromosomal organization so they can have defects with their chromosomes, just like us. So while they don’t specifically have Down Syndrome, they can have a chromosomal defect resembling Down’s.
Researchers have learned that mice can have a trisomy in chromosome 16 and will actually genetically create this trisomy to learn more about how animals are affected by it. These genetically engineered mice have very similar characteristics of Down’s that humans have, but this abnormality does not naturally occur. Even if it did naturally occur without human interference, it would still not be Down Syndrome since Down’s only affects humans.
Animals do not have the type of prenatal testing like humans do, so if one of the fetuses have a trisomy it would not be known until the animal is born (the likelihood of survival after being born is extremely low). More often, however, the fetus will die before it is even born.
Down syndrome in Monkeys
While chimps and monkeys have extremely similar DNA from humans (we share 99% of the same DNA with them) they still cannot have Down Syndrome. What does happen in chimps is they have a trisomy of the 22nd chromosome, which was discovered back in 1969. It is not clear how frequently trisomy 22 appears in chimps, but when it does happen there is a possibility of the mother rejecting the child. When in captivity that means caretakers need to care for the chimp, which is the case with Kanako. Kanako is a chimp born in 1992 that has trisomy 22. Her mother rejected her and she has been raised by caretakers since. She is blind in both eyes, had stunted growth, and has a heart disease. Kanako is only the second documented case of trisomy 22 and she is helping researchers learn more about trisomy 22 in not just chimps, but as well as trisomy 21 in humans.
Kenny the Tiger
Some of you might remember the debacle of Kenny the tiger, the tiger who “had Down Syndrome” due to inbreeding. He was not diagnosed with Down Syndrome (like some people said he was), what he had was a defect that was extremely similar to Down’s. Kenny, unfortunately, passed away back in 2008 due to negligent breeding.
Kenny’s parents were actually siblings that were forced to breed. Most of Kenny’s siblings stillborn, and the few that survived died early in their lifetime. Kenny died at the age of 10. The average lifespan of a tiger in captivity is over 20 years.