Chimpanzee With Down Syndrome, And Animals That Don’t Have It

On February 21, Springer Link published an article about a chimpanzee with Down syndrome, one of the few animals ever recorded to have the genetic disorder.

The chimpanzee with Down syndrome is only the second reported case in the species, a disorder which is referred to as Trisomy 22.

More specifically, Trisomy 22 involves chromosome pair 22, which is similar to chromosome pair 21 in humans. Human cells have 23 pairs of chromosomes compared to the 24 pairs in apes.

The heartbreaking story of the second chimp in history found to have 'Down syndrome' https://t.co/F0S6hdes2d pic.twitter.com/NpJ41s8oSS

— Daily Mail Online (@MailOnline) February 22, 2017

The report states that the chimpanzee with Down syndrome has infantile cataract and vision problems, which she developed before the age of one. She also has Nystagmus, a condition that causes involuntary eye movement; Strabismus, or a misalignment of the eyes; the chimpanzee also has a progressive thinning of the cornea called Keratoconus, which is the reason the chimpanzee became blind by the time she was 7-years-old.

To add, the Down syndrome in the chimpanzee also resulted in a condition called Hypodontia, which means that her permanent teeth are underdeveloped. She reportedly also has a severe overbite as a result.

But the chimpanzee has a more severe condition, which is referred to as a congenital atrial septal defect, or a hole in her heart wall. A research team determined this when they conducted a chromosomal analysis on the chimpanzee in 2014.

Born in captivity in 1992, the 24-year-old chimp is named Kanako and resides at the Kumamoto Sanctuary Wildlife Research Centre at the Kyoto University, where she was transferred to in 2011 from a private company.

Science Daily explains Kanako’s case by pointing out the chromosomal differences between chimps and humans where a third copy of chromosome pair 21 is known to cause Down syndrome in humans just like a third copy of 22 does for apes.

The Springer Link article seems to simply confirm that this is, in fact, the second case of Down syndrome reported in a chimpanzee, where the last and first reported cases goes back as far as 1969. At the same time, it also documents the developmental issues impacting the chimpanzee.

It should be mentioned that the first chimp recorded to have the disorder died before their second birthday.

Primates are Animals that resemble humans the most, and so it is likely that any treatment for a congenital atrial septal defect is the same where it would require surgery. According to the Center for Disease Control (CDC) site, the condition causes the increase of blood flow to the lungs, which also causes more damage to the blood vessels, and, in time, will lead to heart failure.

While a search for other animals with Down syndrome does pull up some results, the claim that tigers, cats and other animals other than primates have the disorder is questionable, according to Broadly, which says that animals that appear to have the look of the disorder have fallen victim to the internet listicle.

The National Human Genome Research Institute, which is a government organization under the National Institutes of Health, posted a question and answer from the National DNA Day Moderated Chat held in April, 2008, which was over whether animals can get Down syndrome.

“Yes. There have been several chimpanzees found with Down Syndrome. As the syndrome is caused by an extra copy of a specific chromosome (chromosome 21 in humans) only animals closely related to humans have a similar syndrome. Extra copies of other chromosomes cause even more serious syndrome and most are not compatible with life. To study Down syndrome, scientists have created mice that have extra copies of the same genes found on human chromosome 21. These mice have some of the features of Down Syndrome.”

The sanctuary where Kanako resides is the first and the only one of its kind in Japan. The Wildlife Research Centre is the sister institute for the Primate Research Institute of Kyoto University. There are reportedly 58 chimps and six bonobos at the sanctuary, which is not open to the public.

It has been reported that her engagement with other chimps has been restricted for fear that interactions with another chimpanzee might become aggressive.

It’s unknown the extent of retardation with Kanako, according to the lead researcher Satoshi Hirata.

“The lack of abnormalities noted in her daily care-taking before the age of one, except for neonatal inactivity and limp limbs, suggests that there was no severe retardation in her behavioral development.”

While there have been cases of inbreeding among humans which led to the disorder, it’s unknown what the causes of Kanako’s disorder are. As mentioned before with experiments on mice, the appearances of the disorder are seen on some animals, but cognitive similarities to humans is unknown.

Kanako has been given the opportunity to interact once a month with another chimpanzee named Roman, who has reportedly been “calm and friendly to Kanako from the start,” according to Science Daily.

The lead researcher of the published paper has devoted his research to the chimpanzee with Down syndrome, along with other primate animals at the sanctuary.

[Featured Image by Kateryna Kon/Shutterstock]