Heritability estimates
Each of the four variants identified in the GRS analysis individually accounts for up to 1.4% of the heritability of recurrent wheeze (rs3816470, 1.3%; rs3902920, 1.3%; rs8076131, 1.4%; rs12603332, 1.4%). In comparison, the GRS, which combined the weighted effects of all four variants, explained for 2.0% of the variance in recurrent wheeze (Table 1 ). When the breastfeeding interaction term was added, 2.7% of variance in recurrent wheeze was explained. When both breastfeeding and NO2 exposure interaction terms are added, 3.6% of recurrent wheeze was explained.
The four variants identified in GRS each explained for up to 1.5% of the variability in asthma (rs3816470, 1.25%; rs3902920, 1.12%; rs8076131, 1.13%; rs12603332, 1.51%). When the weighted effect of the four variants were combined in the GRS, this explained for 1.8% of the variance in asthma. When breastfeeding interaction term is added, 2.0% of asthma can be explained. When both breastfeeding and all NO2 exposure interaction terms are added, 2.1% of asthma could be explained (Table 1 ).