What is Down syndrome?
Down syndrome is a chromosomal condition. Normally humans have 23 pairs of chromosomes- 22 pairs of somatic and 1 pair of sex chromosomes, making the total count of 46 chromosomes. In case of Down syndrome there is an extra chromosome 21, making the total chromosome count 47. In some cases, chromosome 21 trisomy is not present in all of the cells, but only in some of them – mosaic Down Syndrome.
Clinical symptoms for individuals with Down syndrome vary severely. In most cases Down syndrome can be diagnosed during pregnancy, using various tests. These tests can also reveal other syndromes like Turners syndrome, William syndrome and many other conditions.
Children born with Down’s syndrome can usually be diagnosed by observing the classic features:
- Short neck, arms and legs
- Flat face
- Flattened nose
- Far-placed, upwards slanting eyes
- Single line horizontally across the palm
- Poor muscle tone at birth
- Small ears
- Big tongue
Other clinical features that can be detected after birth are:
- Congenital heart disease
- Hearing loss
- Intellectual disability
- Eye diseases, such as cataracts
- Leukemia early in life
Can animals have Down syndrome?
There have been various reports on various animals, like dogs, cats, gorillas and tigers having Down syndrome. Down syndrome can only be present in humans, because this syndrome occurs when there is an extra 21 chromosome. Still, there have been cases reported about Chimpanzees having Down syndrome, since they are closely related to humans.
Mostly animals are believed to have Down syndrome because of their features and behaviour that is similar to people who suffer from Down syndrome. Although Down syndrome is not a disease commonly present in animals, they can have other chromosomal abnormalities.
Tiger with Down syndrome
White tiger Kenny is one of the most famous cases of an animal having Down syndrome. White tigers are not separate species of tigers- they are Bengal tigers, who are born when two tigers with the recessive gene that controls the white colour of the fur, breed.
It is believed that all white tigers have originated from one single tiger and have been inbreed since. These tigers are very popular amongst pseudo-sanctuaries, exhibitors and zoos, since they attract more visitors. In order to have the white coloured tiger, breeders must pair tiger fathers and daughters, granddaughters and so on. This causes many genetic problems, like:
- Skeletal deformities-scoliosis, cleft palate
- Crossed eyes
- Mental impairment
Kenny is one of the white tigers that was selectively inbreed in a zoo in United States. In many cases, when a white tiger is born with genetic abnormalities, breeders dispose of them. Kenny had severe mental retardation, physical limitations and facial features that are similar to patients suffering from Down syndrome. Read about other chromosomal disorders: Edwards syndrome, Cowden syndrome.
Kenny was rescued from a breeding facility in 1999 and lived in Turpentine Creek Wildlife Refuge until his death in 2008. He was only 10 years old when he died- half a lifespan of a normal tiger .
- What is Down syndrome: https://ghr.nlm.nih.gov/condition/down-syndrome#diagnosis
- Symptoms of Down syndrome: https://www.cdc.gov/ncbddd/birthdefects/downsyndrome.html
- Down syndrome in animals: http://www.petmd.com/dog/conditions/can-dogs-have-down-syndrome
- Information about white tigers: http://www.wildcatsanctuary.org/the-truth-about-white-tigers/
- Kenny the tiger: http://www.snopes.com/tiger-with-down-syndrome/