Filaggrin mutations, atopic eczema, hay fever, and asthma in children.
BACKGROUND
Mutations in the filaggrin gene (FLG) have been shown to play a significant role in ichthyosis vulgaris and eczema, 2 common chronic skin diseases. However, their role in the development of other atopic diseases such as asthma and rhinitis has not yet been clarified in large population-based studies.


OBJECTIVE
To study the effect of FLG mutations at the population level and their effect on other atopic phenotypes.


METHODS
Association analysis of the 2 common FLG-null mutations R501X and 2282del4 and 3 recently identified rare FLG variants (R2447X, S3247X, 3702delG) was performed on our cross-sectional population of German children (n = 3099) recruited as part of the International Study of Asthma and Allergies in Childhood II in Munich (n = 1159) and Dresden (n = 1940).


RESULTS
FLG variants increased the risk for eczema more than 3-fold (odds ratio [OR], 3.12; 95% CI, 2.33-4.173; P = 2.5 x 10(-14); population-attributable risk, 13.5%). Independent of eczema, FLG mutations conferred a substantial risk for allergic rhinitis (OR, 2.64; 95% CI, 1.76-4.00; P = 2.5 x 10(-6); population-attributable risk, 10.8%). Nasal biopsies demonstrated strong filaggrin expression in the cornified epithelium of the nasal vestibular lining, but not the transitional and respiratory nasal epithelia. In contrast, the association with asthma (OR, 1.79; 95% CI, 1.19-2.68; P = .0048) was restricted to asthma occurring in the context of eczema, and there was a strong association with the complex phenotype eczema plus asthma (OR, 3.49; 95% CI, 2.00-6.08; P = 1.0 x 10(-5)).


CONCLUSIONS
Our results suggest that FLG mutations are key organ specific factors predominantly affecting the development of eczema and confer significant risks of allergic sensitization and allergic rhinitis as well as asthma in the context of eczema.
Weidinger
Stephan
S
Department of Dermatology and Allergy, Technical University Munich, Munich, Germany. weidinger@lrz.tum.de
O'Sullivan
Maureen
M
Illig
Thomas
T
Baurecht
Hansjörg
H
Depner
Martin
M
Rodriguez
Elke
E
Ruether
Andreas
A
Klopp
Norman
N
Vogelberg
Christian
C
Weiland
Stephan K
SK
McLean
W H Irwin
WH
von Mutius
Erika
E
Irvine
Alan D
AD
Kabesch
Michael
M
D001249:Asthma / Q000235:genetics*; D002648:Child; D003430:Cross-Sectional Studies; D003876:Dermatitis, Atopic / Q000235:genetics*; D005260:Female; D000091344:Filaggrin Proteins; D020022:Genetic Predisposition to Disease; D005838:Genotype; D006801:Humans; D007381:Intermediate Filament Proteins / Q000096:biosynthesis / Q000235:genetics*; D008297:Male; D009154:Mutation; D009297:Nasal Mucosa / Q000378:metabolism; D016133:Polymerase Chain Reaction; D006255:Rhinitis, Allergic, Seasonal / Q000235:genetics*
C000717249:FLG protein, human; D000091344:Filaggrin Proteins; D007381:Intermediate Filament Proteins