The Cancer Research Campaign (CRC) is funding a study into the possible genetic causes of malignant melanoma, the most serious form of skin cancer.

It kills up to 1,500 people in the UK every year and is on the increase.

The CRC researchers say people with a large number of moles are more likely to get melanoma, but they do not know why.

They believe the genes responsible for moles could be behind melanoma.

Dr Doug Easton, from the CRC's Centre for Genetic Epidemiology in Cambridge, said: "We already know of one skin cancer susceptability gene, but believe there are many more which have not yet been discovered."

He added that, by looking at families with a large number of siblings, it would be easier to trace genes which might make people susceptible to cancer.

New treatments

The CRC says the research could lead to new treatments for melanoma by showing how genes react with sunlight to form cancer.

It could also result in advice on better protection from skin cancer for people with large numbers of moles.

The study will last four years and the CRC hopes to recruit up to 400 siblings to give it a large enough base to be representative.

Volunteers, who should be aged between 18 and 60 and preferably have at least three or four siblings, will only have to give up a few hours of their time.

They will be asked to go to Addenbrookes Hospital in Cambridge and fill in a questionnaire, have their moles examined and give a blood sample.

Professor Gordon McVie, director general of the CRC, said: "Malignant melanoma is the fastest growing cancer, so it is particularly important that we discover the genes responsible."