Rare case of Down Syndrome documented in a chimpanzee

A 24-year-old chimpanzee living in Japan has been diagnosed with a condition called trisomy 22 that is similar to Down Syndrome in humans.

Trisomy 22 is caused by the production of an extra copy of chromosome 22 in apes such as chimpanzees, gorillas, or orangutans.

The female chimp affected is named Kanako, and was born in captivity.

Hers is the second known case of trisomy 22 among chimpanzees, and she is, in comparison, faring quite well.

The first documented diagnosis was made in 1969, and the animal died before reaching the age of 2.

Though Kanako has certainly lived much longer, her health is not without complications.

She suffers from heart disease, her teeth have not fully developed, and she has been blind for the past 15-or-so years.

As she is unable to see, social interactions with other chimps are often difficult.

Her human caretakers at Kyoto University's Kumamoto Sanctuary, Wildlife Research Centre have determined it best she lives alone, but she does enjoy regular visits from an especially low-key chimpanzee named Roman.

Satoshi Hirata, one of the researchers, notes that it's tough to estimate how common the condition is but estimates it could occur in as many as, "1 in 600 births."