A new study has suggested that cat exposure at birth coupled with a genetic mutation may make a child more prone to develop eczema during first year of life.
Filaggrin is a protective protein normally found in skin. It acts as a physical barrier to potentially harmful substances in the environment.
Led by Professor Hans Bisgaard (University Hospital Gentofte, Copenhagen, Denmark), the researchers studied the association between mutations in the filaggrin gene (FLG) and exposure to environmental factors with the development of eczema.
It is know that Eczema is hereditary and evidence suggests it is caused by genetic and environmental factors. Recently, the researchers discovered that two common "loss-of-function" variants in the gene encoding filaggrin (FLG) predispose people to eczema. The researchers hypothesized that inheriting one or two defective FLG genes might weaken their physical barrier, affecting their response to environmental substances.
This hypothesis was tested by conducting a cohort study in two independent groups of infants - a high-risk group consisting of 379 infants born in Copenhagen, Denmark to mothers with asthma and a group of 503 infants born to women from the general population in Manchester, UK.
Later, it was found out which FLG variants each child had inherited and classified those with either one or two defective copies of FLG as having an FLG mutation. They determined pet exposure in early life by asking whether a dog or a cat was living in the parental home when the child was born and then analyzed how these genetic and environmental factors affected the age of onset of eczema.
They found that in both groups, children with FLG mutations were twice as likely to develop eczema during the first year of life as children without FLG mutations. In case of children without FLG mutations, cat ownership at birth had no effect on eczema risk but for children with FLG mutations, cat ownership at birth (but not dog ownership) further increased the risk of developing eczema.
These results indicate that filaggrin deficiency causes weakening of the skin's protective barrier, increasing a child's susceptibility to factors associated with cat exposure.
If confirmed, these findings suggest that, filaggrin-deficient individuals may need to avoid cats (but not dogs) during the first few months of life to reduce their risk of developing eczema.
The study is published in the recent issue of PLoS Medicine.