Nature and nurture both play a role in eczema, but few genes have been linked to specific environmental risks. Now a gene mutation that predisposes youngsters to the skin condition seems to pose a greater risk if they are also exposed to cats.

In 2006, a mutation in the gene for the protein filaggrin – which helps keep foreign substances out of the skin – was shown to increase the risk of eczema. About 9% of people of European origin carry this mutation.

To find out whether an environmental trigger might also play a role, a team led by Hans Bisgaard of the Gentofte University Hospital in Copenhagen, Denmark, who was also involved in the 2006 work, tracked 358 Danish and 460 British children from birth.

About 25% of children without the mutation developed eczema, compared with 45% of those with the mutation. However, of the 16 children who both had the mutation and lived with a cat, 14 developed eczema, all between the ages of one and three months.


“It has been very hard to prove that there really are environmental factors that trigger those genes,” Bisgaard says. “This is proof that there is an interaction, even in the first month of life.” However, Bisgaard says that much more data is needed before any prescriptions can be made for parents.

“It’s an interesting and convincing finding,” says Natalija Novak, a dermatologist and epidemiologist at the University of Bonn in Germany. But she says we should now look for other environmental factors that correlate with eczema.

Journal reference: PLoS Medicine (DOI: 10.1371/journal.pmed.0050131)