Cold sores have genetic link, study says

By By Carlos Mayorga

By Carlos Mayorga

Millions of Americans suffer from recurring cold sores as a result of herpes simplex virus, but U researchers may have discovered the hereditary link to herpes, which could lead to more effective treatment of cold sore outbreaks.

“We want to know why people are getting cold sores and why some don’t, which gene or genes triggers the dirty deed and figure out how we can inhibit it,” said John Kriesel, a professor in the School of Medicine’s Division of Infectious Diseases.

The study, which was published in the Feb. 1 issue of The Journal of Infectious Diseases, points to six specific genes in human chromosome 21, which has 1,000 to 1 odds of having a link to cold sores.

HSV exists in two forms, type 1 (HSV-1), which is linked to the vast majority of cold sores, and type 2 (HSV-2), which is primarily responsible for genital herpes.

Cold sores caused by HSV-1 make up the most common recurring viral infection along with herpes keratitis, an eye infection that can cause scarring and blindness.

Kriesel said finding out how people inherit the susceptibility to herpes could help researchers develop new drugs to reduce herpes outbreaks. Identifying the gene or group of genes that causes outbreaks might make “excellent targets” for where to apply new drugs.

“The drugs we use today (to treat herpes) are not that effective,” Kriesel said. “Some people get a tingle on their lip before a cold sore forms, so if you jump on it right away, it can reduce the outbreak severity by only one-third.”

Researchers collected DNA from 421 people from 39 large, multi-generational families in Utah to “determine which parts of the genome were linked with frequent cold sores,” said Maurine Hobbs, the study’s first author and a professor in the U’s division of endocrinology and metabolism.

The families filled out questionnaires about their health histories, and researchers were able to group them according to how frequently the individuals experienced cold sore outbreaks.

Researchers used a process called linkage analysis for the study, which looks at genetic markers in each family to find regions where genes that house disease could lie.

Of the individuals who had proven to be infected with HSV-1, researchers compared those frequently affected with unaffected individuals to determine the “biology behind when you have an outbreak and what triggers it,” Hobbs said.

“We were able to find chromosomal regions with good candidate genes,” Hobbs said.

Individuals who couldn’t be categorized were excluded from the study, in addition to 111 people who were only mildly affected.

“We find that the risk of having frequent outbreaks of herpes cold sores are 20 percent heritability,” Hobbs said.

But outbreaks are also the result of an interplay of genetics and environment, like stress, exposure to the sun and anything that affects the immune system, such as a cold, Kriesel said.

Hobbs said that they are now working with mice to look at the six specific candidate genes to pinpoint an exact gene or group of genes that affects the ability of the virus to reactivate in the knock out mice, which could lead to new ways to treat outbreaks.

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