Estrogen receptor 1 polymorphisms are associated with airway hyperresponsiveness and lung function decline, particularly in female subjects with asthma

Background: Sex hormones may contribute to the higher prevalence and severity of adult asthma in women compared with men. Objective: Sequence variants in the estrogen receptor α gene (ESR1) may alter estrogen action in asthma. Methods: Two hundred asthma probands and their families (n = 1249) were genotyped for 5 single nucleotide polymorphisms (SNPs) in the ESR1 gene (intervening sequence 1 [IVS1]-1505A/G, IVS1-1415T/C, IVS1-397C/T, IVS1-351G/A and exon1+30T/C). Association with asthma and bronchial hyperresponsiveness (BHR) were tested. In the asthma probands, association of SNPs with BHR severity and annual FEV₁ decline were determined. Results: No SNP was associated with asthma. IVS1-397 was significantly associated with the presence of BHR (P = .02) and interacted with sex; female subjects with the CT or TT genotype were at risk (P = .01). In asthma probands, all SNPs were associated with FEV₁ decline. Exon1+30 CT and TT group had an excess decline of 11.6 mL/y (P = .03) and 15.7 mL/y (P = .01), respectively, compared with the CC group. Of the IVS1 polymorphisms, IVS1-351G/A showed the strongest association, with the AA group having excess decline of 16.1 mL/y (P = .01) compared with the GG group. In subanalyses by sex, these associations were significant only in female subjects. Conclusion: ESR1 gene variants may affect development of BHR, particularly in female subjects. They may also lead to a more rapid lung function loss in patients with asthma, and in female subjects specifically. This may result from altered estrogen action, which affects lung development and/or airway remodeling. Further studies on ESR1 gene variations are important to understand better the origin of sex differences in asthma. Clinical implications: Variations in the gene encoding estrogen receptor α are associated with BHR and a more rapid annual lung function decline, especially in female subjects. Even though this has no diagnostic or clinical implication, it may open avenues for future sex-specific treatment in asthma.