Numbers count in the genetics of moles and melanomas

New research, carried out over nine years with a cohort of more than 1,200 people, will help dermatologists determine a patient’s risk of developing melanoma – and it is a numbers game.

Associate Professor Rick Sturm from The University of Queensland has revealed his team have uncovered the specific gene variations affecting the number and types of moles on the body and their role in causing skin cancer. “The goal was to investigate the genetic underpinnings of different mole classes ‘naevi types’ and understand how these affect melanoma risk,” A/Prof Sturm said.

The findings will help dermatologists to better understand mole patterns and provide more holistic care to patients who may be at risk of melanoma.

“Based on our work, the number of moles in each category can give a more complete assessment of melanoma risk rather than just the number of moles alone.”

Three key mole classes – reticular, globular and non-specific – were magnified to assess their pattern and risk factors.

“We found people who had more non-specific mole patterns increased their melanoma risk by two per cent with every extra mole carried,” he said.

“As we age, we tend to increase the amount of non-specific moles on our body, and the risk of developing melanoma increases.”

Their results were then overlayed with genetic testing, which found variations in four major genes.

“We found some major relationships between genes and the number of moles and patterns when looking at the DNA,” A/Prof Sturm said.

“Certain gene types influenced the number of different naevi types -- for example, the IRF4 gene was found to strongly influence the number of globular naevi found on the body.”

“For a long time, clinicians have been interested in how pigmented moles relate to melanoma and melanoma risk,” he said.

“With the availability of dermoscopes and imaging, these results provide a new layer of understanding to guide clinical practice.”

Reticular naevi pattern (left) Gene variations: MTAP, PLA2G6, MITF. Globular naevi pattern (right) Gene variations: IRF4.

Pictured above,  Associate Professor Rick Strum, Kasturee Jagirdar and Darryn Smit. Credit: University of Queensland   

This research is published in Journal of Investigative Dermatology and is available here