Study: Human genes evolve naturally to protect against inherited diseases

Thursday, May 19, 2016 by: David Gutierrez, staff writer
Tags: human genes, inherited diseases, Mendelian conditions

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(NaturalNews) A very small proportion of the human population may have some trait that makes them immune to certain inherited genetic diseases, according to a study published in the journal Nature Biotechnology.

"Millions of years of evolution have produced far more protective mechanisms than we currently understand," said Eric Schadt, founding director of the Icahn Institute, which led the research. "Characterizing the intricacies of our genomes will ultimately reveal elements that could promote health in ways we haven't even imagined."

The researchers hope to discover what it is about the genomes of certain people — dubbed "superhero DNA" — that protects them, and whether doctors can somehow transfer that protection to others.

Seemingly immune

During the course of DNA replication, some errors naturally arise. In certain cases, a coding error on a single gene can be enough to result in a disease; these diseases are known as "Mendelian conditions." If a person carries two copies of the bad gene variant, they develop the disease. More than 6,000 Mendelian conditions have been identified, and there are more than 150,000 disease-associated variants of them.

Many studies have sought to better understand Mendelian conditions by studying the people who have developed them. But in the new study, the researchers wondered if there might not be people who remain healthy in spite of having two of the genes.

"Most genomic studies focus on finding the cause of a disease, but we see tremendous opportunity in figuring out what keeps people healthy," Schadt said.

The researchers combed through worldwide databases of human DNA sets collected from a total of 589,306 people. From this, they identified people with one of eight Mendelian conditions: cystic fibrosis, Smith–Lemli–Opitz syndrome, familial dysautonomia, epidermolysis bullosa simplex, Pfeiffer syndrome, autoimmune polyendocrinopathy syndrome, acampomelic campomelic dysplasia and atelosteogenesis. They then reviewed the medical records associated with those DNA samples.

Within that large sample, they found 13 people who, according to their DNA, should have developed a Mendelian condition but who had no mention of it in their medical records. Because the eight conditions studied are so severe, the researchers said, it is "highly unlikely that such an individual would have manifested the disease without it being clearly annotated in their health records."

The researchers concluded that there must be another factor that protects a small number of people from manifesting certain genetic diseases.

Logistical and ethical questions remain

The natural next step in the research would be to follow up with the 13 people and perform further studies upon them.

"Finding these individuals is a starting point to searching for the other changes, [such as] in the genome, that might give us clues to develop therapies," said researcher Stephen Friend. "Study the healthy, don't just study the sick."

That will not be possible, however, as no identifying information was recorded during the studies those people were a part of.

This also makes it impossible to perform followup tests and rule out alternative explanations for the apparent immunity, including bad record keeping, mild forms of the conditions, faulty DNA tests or mosaicism (in which only certain cells in the body express a genetic trait).

To address these concerns, the researchers are planning a new study to collect DNA from large numbers of people who have signed release forms to be contacted again in the future. The researchers hope to also investigate whether some people are immune to other conditions, such as dementia or certain infections.

While there seem to be clear benefits to be gained from such studies, they also raise ethical questions. Many individuals are reluctant to give researchers the private information that can be revealed by perusing their genome and are rightly concerned about who else might learn that information once it becomes available.

Sources for this article include:

RT.com

Nature.com

BBC.com

Science.NaturalNews.com