By Sky News

Experts have warned that an online genetic screening company is giving consumers false reassurance about their future risk of disease.

The company, 23andMe, scans DNA in saliva samples looking for mutations which have been linked to more than a dozen diseases, including cancer.

The service is marketed direct to consumers, without counselling from a doctor.

However, Professor Shirley Hodgson, a genetics counsellor at St George's Hospital in London, told Sky News that the test excludes major genes for prostate, breast and colon cancer.

"That is my main concern," she said.

"Someone may have a gene profile and think they're at low risk of prostate cancer, when in fact their father and grandfather both died of prostate cancer.

"They might have had a strong genetic predisposition and you might have inherited it from them.

"It's a worry that these are being presented completely without genetic counselling."

23andMe is one of two online companies targeting gene screening at European consumers with a personal genetic profile costing around £500.

Co-founder Linda Avey says consumers have a right to their genetic information.

They're even told whether or not they're protected against the commonest strain of HIV.

She said: "We're not going to try to inflict different moral capacities on them, that's just not our role. It's just information that's coming out of the research community that we're giving back to our customers.

"We're not going to filter that based on whether or not it's suitable to convey to them."

But Dr Christine Patch, a member of the Human Genetics Commission, said such sensitive genetic information should come with the support of a genetics counsellor.

"Telling people they are protected against some strains of HIV could have public health consequences if they don't understand it. They could go on to have unprotected sex."

23andMe says it does give consumers information to help them interpret their test results. It suggests those who are still uncertain should consult a doctor.

Howard Blanchard has used the service. He was concerned about his inherited risk of serious medical conditions.

Both his father and sister have needed organ transplants and his mother has arthritis.

His results show he has genes that raise his risk of obesity, diabetes and arthritis. He said he was reassured.

"I'm not worried about any of them striking me down because it doesn't work like that. It's probability. But if I can change my diet or behaviour, then maybe I can offset the chances of getting the diseases."

23andMe's investors include the internet search giant Google. The company aims to reduce the cost of genetic profiling to reach 98% of the world's population.