FEB 25, 2017 10:00 AM PST

Meet the 24-Year-Old Chimp with Down Syndrome

WRITTEN BY: Xuan Pham

Japanese scientists have confirmed the diagnosis of Down syndrome in a 24-year-old female chimp named Kanako. This marks only the second documented occurrence of this condition in a chimpanzee.

Image: Kanako at the Kumamoto Sanctuary

Kanako was born in captivity at the Kumamoto Sanctuary and developed some abnormal characteristics that set her apart from other chimps. Her eyes, for example, were crossed and at the age of one, she developed cataracts. She became blind at the age of seven. In addition, she also had some heart abnormalities and underdeveloped teeth.

Recent exams later revealed that Kanako has a third copy of chromosome 22, otherwise known as trisomy 22.

These characteristics all mirror Down syndrome in humans, which is genetic condition caused by the presence of all or part of an extra chromosome 21. A full extra copy of chromosome 21 is often referred to as trisomy 21.

Patients with Down syndrome exhibit some craniofacial dysmorphology, such as overall reduced skull size, flat head, epicanthal folds, flat nasal bridge, and open mouth. In addition, one of the most affected organs in Down syndrome is the brain. Down syndrome patients present with an overall smaller brain size, specifically smaller cerebellum and hippocampus. This can result in a range of cognitive impairments, such as learning and memory deficits. In fact, trisomy 21 is the most frequent genetic cause of mental retardation.

The rest of the body can also be perturbed due to the dosage imbalance of an extra 21 chromosome, including clubbed digits, curved pinkie, wide 1-2 toe gap, and shortened stature. Down syndrome patients also show an increased incidence of congenital heart disease and Hirschsprung’s disease.

Because the confirmation of trisomy 22 was only recently confirmed for Kanako, it’s not entirely clear how this condition has affected her development. For example, while mental retardation is present in many Down syndrome patients, Kanako’s caretakers say there’s little evidence of this trait in the chimp.

At 24-years-old, Kanako’s is currently the oldest chimp diagnosed with trisomy 22. The only other instance of trisomy 22 was documented in 1969, but the chimp only lived for less than two years.

Scientists aren’t too sure how common Down syndrome is in chimps. However, they suspect the rate isn’t too far off from humans. "It is difficult to estimate the probability of a rare event using a small population, but given that around 500 chimpanzees have been born in captivity in Japan, the probability of this autosomal trisomy in chimpanzees may be comparable to that of trisomy 21 in humans, which occurs in up to 1 in 600 births," said Satoshi Hirata, the lead investigator for Kanako’s case study.

Additional sources: Springer

About the Author
  • I am a human geneticist, passionate about telling stories to make science more engaging and approachable. Find more of my writing at the Hopkins BioMedical Odyssey blog and at TheGeneTwist.com.
You May Also Like
AUG 20, 2020
Cardiology
A New Test to Discern Kawasaki Disease from Sepsis
AUG 20, 2020
A New Test to Discern Kawasaki Disease from Sepsis
Kawasaki disease is a rare cardiovascular disease affecting children under the age of five. If untreated, there is a cha ...
AUG 27, 2020
Clinical & Molecular DX
Genetic Tool Predicts Breast Cancer Risk in Women of Asian Ancestry
AUG 27, 2020
Genetic Tool Predicts Breast Cancer Risk in Women of Asian Ancestry
  Many diseases such as breast cancer have both a strong genetic component, coupled with a variety of environmental ...
SEP 02, 2020
Cancer
Does Adjuvant Chemotherapy Really Help in a Rare Signet-ring Cell Carcinoma
SEP 02, 2020
Does Adjuvant Chemotherapy Really Help in a Rare Signet-ring Cell Carcinoma
For many rare diseases, there is a lack of a “standard” treatment options. This is more prevalent in diverse ...
SEP 07, 2020
Cell & Molecular Biology
With Nanopores, Small Samples Detect Diseases
SEP 07, 2020
With Nanopores, Small Samples Detect Diseases
If you've ever been through a battery of tests while doctors try to find a diagnosis for an ailment, you know that many ...
NOV 05, 2020
Clinical & Molecular DX
Painless Microneedle Patch Diagnoses Malaria in Minutes
NOV 05, 2020
Painless Microneedle Patch Diagnoses Malaria in Minutes
It looks like a Band-Aid — a small, adhesive patch that is applied directly to the skin. This simple, low-cost dia ...
NOV 07, 2020
Neuroscience
Device Measures Stress Hormones with Earwax
NOV 07, 2020
Device Measures Stress Hormones with Earwax
Researchers from University College London and King’s College London in the UK have developed a device that can me ...
Loading Comments...