Finding the mutation that causes a disease is difficult, so the research team was excited to discover mutations for both of Lil Bub’s rare traits. Photo courtesy of, Mike Bridavsky.

A team of scientists has made an incredible discovery, and it’s all thanks to Lil Bub and his unique genome!

Feline celebrity Lil Bub is famous for her congenital abnormalities – extra toes, short limbs and a tongue that sticks out just a bit too far. These quirks are undeniably adorable, and have made Lil Bub one of the most beloved cats on the internet. More recently, they offered scientists an exceptional opportunity. A crowdfunding effort allowed a team of researchers to sequence Lil Bub’s genome, and they discovered that the beloved feline’s quirks aren’t a result of one genetic abnormality, but two!

The results revealed that Lil Bub’s osteopetrosis (which leads to unusually dense bones and short stature) is caused by a missing letter in her genetic sequence. This causes a shortened (and non-functional) version of a protein, which ultimately creates an imbalance between building and resorbing bone.

“The other mutation does not change any proteins directly, but it affects a DNA switch,” says Orsolya Symmons, one of the lead researchers. “That protein, called ‘sonic hedgehog’, is turned on in a part of the developing limbs where it’s normally off. This created the additional digits on Lil Bub’s paws.”

Since osteopetrosis is also present in some humans, the hope is that knowing more about how the disease functions will lead to further discoveries.