A genetic study has found that melanomas on the hands and feet and the inside of the lip are not cause by the sun.

The Australian-led research sheds new light on acral and mucosal melanomas – some of the deadliest forms of the disease – that will have implications on their prevention and treatment, says lead author Professor Richard Scolyer of the Melanoma Institute Australia.

“This is by far the largest study to have looked at the whole genome in melanoma and it has proven these less common melanomas are strikingly different in terms of their causes,” said Professor Scolyer.

Every year in Australia, up to 420 people are diagnosed with acral or mucosal melanomas.

They affect people of all ethnic backgrounds and are the most common forms of melanoma in people with very dark skin.

These forms of melanoma are also often more aggressive and are harder to diagnose which leads to poorer survival outcomes.

Professor Nicholas Hayward from QIMR Berghofer says knowing these are really different diseases to skin melanoma is important for the development of future therapies.

“Acral and mucosal melanomas occur all over the world, but they have been even more challenging to treat than skin melanoma,” Prof Hayward said.

The study published in medical journal Nature also discovered new genetic drivers of acral and mucosal melanomas.

Some mucosal melanomas unexpectedly had mutations in the SF3B1 and GNAQ genes, which had previously only been connected to melanoma of the eye.

Scientists are now working to turn these discoveries into better results for melanoma patients.