Cat Allergies Linked to Eczema

Filaggrin is a protein present in the superficial part of the skin and prevents substances from entering into the deeper layers of the skin. Whenever there is a mutation in the filaggrin gene, a defective filaggrin protein is produced. Because of this mechanism, allergens can easily enter the body producing various allergic reactions. In the present study, researchers evaluated the role of three mutations, namely R501X, 2282del4, and R2247X, in the development of allergic disorders such as eczema, asthma and hay fever. In addition, researchers evaluated the effect of exposure to cats in enhancing the effects of these mutations. They found that there is a high association between filaggrin gene mutation and cat allergy. “We confirm that cat exposure enhances the effect of a filaggrin mutation on the development of eczema and sensitization.”

The development of allergy is a complex process. It involves close interaction between the genes of an individual and environmental exposure to various substances. In some conditions, such as a defect in the filaggrin protein, allergens can easily enter the body and interact with the immune system to produce allergic reactions. Many of the earlier studies concentrated on the conditions in which there is complete absence of the filaggrin protein. But researchers of the present study hypothesized that even a minor mutation of the filaggrin gene can predispose a person to developing an allergic disorder. Hence, they studied the association of R501X, 2282del4, and R2247X mutations with various allergic disorders.

* A total of 10,232 pregnant women of Dutch ethnicity were screened by way of a questionnaire to identify any allergies they had. Out of this, 2,949 women were found to have some form of an allergic disorder.
* All the children of women with allergies were evaluated for the development of  allergies until they were 8 years old. Sensitization in all of them was also noted by measuring specific immunoglobulin E levels.
* DNA was collected from 1,037 children and were tested for R501X, 2282del4, and R2247X mutations in filaggrin gene. Association between these mutations and development of various allergic diseases was analyzed.
* In the last part of the study, it was noted whether exposure to cats enhanced the development of any of the allergic diseases.

* Out of 10,232 pregnant women, 29 percent were found to have some form of an allergic disease.
* The filaggrin mutations were significantly associated with eczema at all ages. A high proportion of children with 2282del4 mutations developed eczema before 1 year of age and almost all showed sensitization by the age of 8 years. In addition, a high association of this gene mutation with hay fever was noted after 5 years of age. No significant association was found between R501X and R2247X mutations and any of the allergic diseases.
* The association between filaggrin gene mutation and eczema was enhanced in children who were living with a cat at home.

Shortcomings/Next steps
This study was conducted on participants belonging to only Dutch ethnicity. In the present study the association between a gene mutation and several allergic diseases only was examined. There is a need to understand the mechanism of such an association. Even the mechanism through which exposure to cats enhances the development of allergy should be investigated.

This study has once again proved the association between defective filaggrin protein and allergic diseases, such as eczema. It has shown a high association between 2282del4 mutation and the allergy of skin. Individuals with these mutations are prone to develop other allergic diseases, such as hay fever and asthma later in their life. This observation can be utilized in the identification of individuals at a risk of developing an allergy, so that some preventive measures can be taken. This study has shown that the risk of sensitization to allergen increases with exposure to cats. Hence, people with filaggrin gene mutation must keep themselves away from cats to prevent the development of eczema and hay fever.

For More Information:
Filaggrin Mutations in the Onset of Eczema, Sensitization, Asthma, Hay Fever and the Interaction with Cat Exposure
Publication Journal: Allergy, March 2009
By M. Schuttelaar; M. Kerkhof; University of Groningen, the Netherlands

*FYI Living Lab Reports Are Summaries of the Original Research.



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