December 20, 2007

RHODE ISLAND – A rare calico cat in Middletown, R.I. is catching the attention of vets and shelters across the nation because of its gender.

Max and his mother were brought to the Potter League for Animals in June. When employees discovered that Max was a male, they phoned local vets. As it turns out, a male calico is rare – only one is born in every 100,000.

A number of vets examined Max and they all had the same response – no one could recall ever seeing a male calico.

Calico is not a breed but rather a sex-linked color pattern. The tri-colored cats are orange, black and white. Variations can exist, which is why some calicos appear to have spots of grey or brown.

Typically, cats are born with two chromosomes. Max has the two that make him male but he also has an extra chromosome that gives him female characteristics.

Because of their unusual chromosome pair, most male calicos are sterile. In fact, only one in 12,000 male calicos can reproduce. Most do not survive more than a few months, due to genetic deficiencies.

Blood samples have been taken and will be used for genetic testing to see if Max has any health issues including whether or not he’s sterile.

Luckily for nine-year-old Max, he is happy and playful and shows no sign of illness.

As it turns out, there’s a human condition that’s very similar – Klinefelter syndrome. Males with Klinefelter syndrome are also born with an extra chromosome in each cell, also giving them female characteristics.

Male calico cats are more of a rarity than those with Klinefelter, which affects one in 500 to 1,000 human males.

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