WEDNESDAY, June 25, 2008 (HealthDay News) -- Infants who have a certain genetic mutation are more likely to develop eczema if there is a cat in the home, a new study suggests.
The idea that genetic mutations associated with a disease can be triggered by environmental exposures is not a new one, the researchers from Denmark and Great Britain noted.
"It's more of an example of a mechanism that's likely to happen between genes and the environment. It's sort of proof of a concept, or an idea that's been around for years," said study author Dr. Hans Bisgaard, of the Danish Pediatric Asthma Center at the University of Copenhagen. "You can have a gene for many diseases but never have the disease if you aren't exposed to triggers."
In the study, infants with the FLG mutation were studied in two groups, a high-risk group in Denmark and a representative sample in Great Britain. Children with the mutation were twice as likely to develop eczema during their first year of life. Those with the mutation and a cat in their home from the time of their birth had a further increased risk of having eczema. The study was published in the June issue of PLoS Medicine.
Eczema, or atopic dermatitis, begins in the first year of life for 65 percent of the people who have the condition, according to the National Institute of Arthritis and Musculoskeletal and Skin Diseases. About 20 percent of all infants and children have symptoms.
Bisgaard explained that the study did not determine how exposure to cats triggered the eczema, but it did demonstrate that the eczema was not an allergic reaction to cats.
"It's probably too early to tell parents to go out and shoot the cat," Bisgaard added, because the finding needs to be replicated. "What is often misleading is that people try to learn some guidance from every new scientific research study. I wouldn't take much guidance from this. I would see it as proof of a concept, the right theory we're working around."
Bisgaard said there are a number of genes that predict asthma and allergies. In the foreseeable future, it is likely "we will be able to profile a child for the risk of these diseases."
In addition to the need to confirm the results before condemning cats, other factors besides the presence of cats need to be considered as potential triggers, added Dr. Marc Riedl, section head for allergy and immunology at the David Geffen School of Medicine at the University of California, Los Angeles. "The cat ownership or exposure could potentially be a surrogate for something else that wasn't measured," he said. For example, there could be a fungal exposure associated with cats, rather than the cats, that sets off the skin reaction, Riedl explained.
Riedl agreed the importance of the study is that "it once again demonstrates gene and environmental interactions in a medical condition. This is another example of how the genetics of an individual convey some susceptibility to environmental exposures."
There's more on atopic dermatitis at National Institutes of Health.
SOURCES: Hans Bisgaard, M.D., University of Copenhagen, Danish Pediatric Asthma Center; Mark Riedl, M.D., assistant professor and section head, allergy and immunology, David Geffen School of Medicine, University of California, Los Angeles; June 2008, PLoS Medicine
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