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.
Department of Microbiology and Immunology, Medical School, University of Tampere, Finland.
Kati
K
Adjers
Tanja
T
Pessi
Jussi
J
Karjalainen
Heini
H
Huhtala
Mikko
M
Hurme
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