Lil Bub is an internet sensation. The tiny cat has over 2 million Instagram followers. She also has a varied career as a published author, a talk show host and a movie star.
Lil Bub was the runt of a feral litter found in Indiana. She grew up smaller than the other cats, with wonky legs and no teeth. This all adds to her charm, but she also holds a secret in her DNA that one day might help with diagnosis and treatment for human disease.
It was molecular geneticist Daniel Ibrahim who made the initial connection. He was watching a documentary on social media-famous cats one evening. During the programme, Lil Bub’s veterinarian shows the x-rays of her dense, curved leg bones. Daniel realised that the cat’s legs looked exactly like a human case of osteopetrosis. He was studying the genetic disorder in people. In humans it can cause a range of symptoms from increased risk of fractures to growth problems, teeth problems and even neurological issues like epilepsy. It has never been reported in cats.
Daniel Ibrahim and his colleague Dario Lupianez got in contact with Lil Bub’s “dude”, Mike Bridavsky. They asked if they could have a sample of her blood in order to sequence her DNA. He immediately agreed, and with the help of a crowdfunding campaign and an international feline genome consortium, they finally managed to unlock her secrets.
One in a million
It turns out that Lil Bub has two very rare genetic mutations. One is a mutation in the gene called Sonic Hedgehog, only seen in a Key West colony of six-toed cats. These cats are descended from Ernest Hemingway’s personal pets. This means Lil Bub is probably related to that long line of famous cats.
The other mutation is potentially even more exciting. In a gene called RANK, Lil Bub had a single letter deletion never before seen in another mammal. After checking the literature, they found a report of a mouse that had a similar (but not identical) mutation in the same gene. The x-rays of the mouse’s legs looked like Lil Bub’s in miniature.
They also cross referenced Lil Bub’s genome against the 99 Lives Consortium, the largest feline DNA database. This confirmed she was unique.
This exciting discovery may lead to advances in identification and treatment of people with osteopetrosis. It has also led to better understanding of Lil Bub’s own health and treatments.
Cats genetics have been studied far less than dogs and primates. However, increased interest in this area could lead to greater understanding of diseases in both cats and people. Lil Bub’s high profile case can only help this. This may lead to better treatments and reduction in hereditary health problems.