Epistatic effect of IL1A and IL4RA genes on the risk of atopy.
BACKGROUND
Several studies have demonstrated a linkage or association of the atopic phenotype with T-cell cytokine genes involved in the regulation of the TH1/TH2 balance (eg, IL4, IL13, and their common receptor, IL4RA). We have recently shown that polymorphism of the pro-inflammatory cytokine IL1A gene is strongly associated with atopy.


OBJECTIVE
We now examined whether the polymorphisms of IL1A (G/T at +4845) and IL4RA (T/C at +22446) would show an epistatic effect on the risk of atopy.


METHODS
Skin prick tests and gene polymorphism analyses were performed in a population-based sample of asthmatic and nonasthmatic subjects.


RESULTS
Our results showed that in the nonasthmatic group the previously described elevated risk of atopy in noncarriers of allele T of IL1A (ie, having the genotype GG) was restricted to individuals who were also noncarriers of allele C of IL4RA (genotype TT). This finding applies to the general population of Finland, where 3.3% of adults are asthmatic.


CONCLUSIONS
These data suggest that the IL1A and IL4RA genes show an epistatic effect on the risk of atopy.
Adjers
Kati
K
Department of Microbiology and Immunology, Medical School, University of Tampere, Finland.
Pessi
Tanja
T
Karjalainen
Jussi
J
Huhtala
Heini
H
Hurme
Mikko
M
D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000483:Alleles; D001249:Asthma / Q000235:genetics / Q000276:immunology; D001483:Base Sequence; D016022:Case-Control Studies; D004247:DNA / Q000235:genetics; D004843:Epistasis, Genetic; D005260:Female; D005387:Finland; D005787:Gene Frequency; D005838:Genotype; D006801:Humans; D006969:Hypersensitivity, Immediate / Q000235:genetics* / Q000276:immunology*; D007375:Interleukin-1 / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D020641:Polymorphism, Single Nucleotide; D019948:Receptors, Interleukin-4 / Q000235:genetics*; D012307:Risk Factors
D007375:Interleukin-1; D019948:Receptors, Interleukin-4; D004247:DNA