Cats can produce allergens that irritate the immune system
Being exposed to cat allergens early in life may spark eczema - if you carry a key gene fault, a study has suggested.
Scientists found having the mutant FLG gene increased the risk of eczema in a baby's first year twofold, but adding exposure to a cat quadrupled that risk.
The study, of 892 babies born in the UK and Denmark, was published in the Public Library of Science journal.
However, a UK expert said other research suggested cats may actually reduce the risk of eczema.
The study, led by a team at the University of Dundee, found exposure to dogs made no difference.
Rates of eczema, which can cause dry, itchy skin, have been rising in the UK in recent years.
The cause of the condition is not fully understood, but it is known that chemicals which cause allergic reactions do seem to trigger flare-ups.
Scientists believe an interplay between these chemicals and our genes may be key to the initial development of the condition.
The Dundee team has been investigating the potential role played by the FLG gene, which it believes is crucial in maintaining the skin's role as a protective barrier.
Some variants of the gene stop it working properly, but faulty genes alone do not explain eczema - as some people appear to carry them and never suffer from the condition.
The Dundee study looked for a connection between "environmental" factors and the triggering of the disease in children.
Working with the universities of Manchester and Copenhagen, the team looked at groups of babies to see what difference exposure to cat, dog and dust mite allergens made to those carrying the variants of the FLG gene.
Researchers found that, on average, the variants on their own roughly doubled the chances of eczema in the first 12 months of life.
In those families who also owned cats at the time of the birth, the risk was almost quadrupled.
There was no significant increase in the risk if there was dog or dust-mite exposure.
The researchers wrote: "Our data suggest that cat but not dog ownership substantially increases the risk of eczema in the first year of life in children with FLG 'loss of function' variants".
However, Dr Michael Cork, a dermatology expert from the University of Sheffield, said the study was relatively small, and the results should be interpreted cautiously.
He said: "There is plenty of other evidence that exposure to cats can actually protect against the development of eczema.
"It is possible that it could actually induce tolerance in children.
"This is a highly complex area, and any results like this need to be weighed alongside other studies."