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 a gene (ESRI) 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 ESRI gene (intervening sequence 1 [IVS1]-1505A/G, IVS1-1415T/C, IVS1-397C/T, IVS1-351G/A and exon 1 +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 a 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.