Amazing - Tiger with down syndrome

Kenny The White Tiger Reveals The Price of Inbreeding

photo credit: Turpentine Creek Wildlife Refuge. Kenny the white tiger has been, probably wrongly, described as having Down Syndrome.

While much of the coverage refers to Kenny as being alive, the Pet Collective report he died in 2008.

The diagnosis of Down’s Syndrome is also questionable. Down’s Syndromeresults from a third copy of chromosome 21. Although a mouse model for Down’s Syndrome exists, tigers have 19 chromosomes to humans’ 23. While Kenny’s face does bear a superficial resemblance to that seen in people with Down’s Syndrome, it’s far from clear that this was the result of a third copy of any chromosome, let alone one that could be matched to our 21st.

What is clear is that Kenny was a victim of the greed of the breeding industry. White tigers are very rare. With so few of them, the genetic pool is limited, and inbreeding is an inevitable consequence. Kenny’s parents were brother and sister. Most of his siblings were stillborn, or died very young, according to Patricia Quinn, a spokesperson for Turpentine Creek Wildlife Reserve, where Kenny lived from the age of two.

A great benefit of having two copies of each of our genes is that damaging recessive mutations are seldom expressed. However, where parents are closely related there is a high chance of them both carrying the same rare version of a gene, with a one in four chance their offspring will inherit it from both sides. With enough damaging alleles in common this becomes like a repetitive game of Russian Roulette.

Despite the repeated deaths, breeders kept trying to mate Kenny’s parents. Although they eventually got two to live, Kenny and his brother Willie could not be sold because of their deformities. He died at the age of ten, around half the lifespan of a typical captive tiger.

“Kenny was non-aggressive, very friendly with our staff members and an obvious favorite with visitors because of his personality. Most people ‘fell in love’ with his friendliness combined with his strange looks. To them, and to us, he was beautiful. He shared his enclosure with his brother for the eight years that he was with us,” says Quinn.

White tigers are an extreme case, but many other species suffer when the desire for “perfect” pets leads toinbreeding. One such example is "purebreeds" of domestic dogs and horses, which suffer from many genetic problems which can shorten lifespans, or cause ongoing disability and pain.. However, the tragedy is doubled in the case of tigers, since were it not for the obsession with breeding "pure whites" these creatures could be allowed to mate with other tigers and preserve the endangered species.