Thirteen people who have been the focus of DNA research are apparently totally unaffected by their faulty genes, scientists say.

Studying the genetic codes of 13 individuals who seem to be miraculously resistant to severe inherited diseases could open the door to life-saving new treatments, scientists believe.

The 13, who have remained healthy despite carrying genetic mutations linked to childhood diseases, were identified by researchers who scoured the DNA of more than half a million people worldwide.

All of them should have been susceptible to Mendelian disorders which can begin in early childhood and are generally caused by defects in just one gene.

Under normal circumstances, anyone carrying such "completely penetrant" mutations will inevitably become ill. An example of a Mendelian disorder is cystic fibrosis.

Yet the 13 people who have been the focus of the new study are apparently totally unaffected by their faulty genes.

They were discovered by scientists involved in the Resilience Project, a retrospective study of more than 589,000 genomes, or complete genetic codes.

The aim was to find rare individuals who are immune to genetic variants that should trigger disease.

Analysis of their genomes could uncover naturally occurring, protective mechanisms that might help scientists develop new treatments for severe inherited disorders.

Each of the 13 individuals appeared to be completely resistant to one of eight Mendelian childhood conditions.

Resilience Project co-founder Professor Eric Schadt, from the Icahn School of Medicine at Mount Sinai, New York City, said: "Most genomic studies focus on finding the cause of a disease, but we see tremendous opportunity in figuring out what keeps people healthy.

"Millions of years of evolution have produced far more protective mechanisms than we currently understand.

Writing in the journal Nature Biotechnology, the scientists explained how progress had been hampered by the fact that the 13 owners of the resistant genomes could not be contacted. The researchers had access to their DNA, but not the individuals themselves.

Commenting on the paper, Dr Daniel MacArthur, from Massachusetts General Hospital in the US, wrote: "The researchers could not re-contact the majority of resilient individuals for further study because of a lack of necessary consent forms.

"Finding genetic superheroes will require other kinds of heroism - a willingness of participants to donate their genomic and clinical data and a commitment by researchers and regulators to overcome the daunting obstacles to data sharing on a global scale."