Abstract
</p>
Background:</p>
Lung function is highly heritable and differs between the sexes throughout life. However, little is known about sex-differential genetic effects on lung function. We aimed to conduct the first genome-wide genotype-by-sex interaction study on lung function to identify genetic effects that differ between males and females.</p>
</p>
</p>
Methods:</p>
We tested for interactions between 7,745,864 variants and sex on spirometry-based measures of lung function in UK Biobank (N=303,612), and sought replication in 75,696 independent individuals from the SpiroMeta consortium.</p>
</p>
</p>
Results:</p>
Five independent single-nucleotide polymorphisms (SNPs) showed genome-wide significant (P<5x10</p>
-8</p>
) interactions with sex on lung function, and 21 showed suggestive interactions (P<1x10</p>
-6</p>
). The strongest signal, from rs7697189 (chr4:145436894) on forced expiratory volume in 1 second (FEV</p>
1</p>
) (P=3.15x10</p>
-15</p>
), was replicated (P=0.016) in SpiroMeta. The C allele increased FEV</p>
1</p>
more in males (untransformed FEV</p>
1</p>
β=0.028 [SE 0.0022] litres) than females (β=0.009 [SE 0.0014] litres), and this effect was not accounted for by differential effects on height, smoking or pubertal age. rs7697189 resides upstream of the hedgehog-interacting protein (</p>
HHIP</p>
) gene and was previously associated with lung function and</p>
HHIP</p>
lung expression. We found</p>
HHIP</p>
expression was significantly different between the sexes (P=6.90x10</p>
-6</p>
), but we could not detect sex differential effects of rs7697189 on expression.</p>
</p>
</p>
Conclusions:</p>
We identified a novel genotype-by-sex interaction at a putative enhancer region upstream of the</p>
HHIP</p>
gene. Establishing the mechanism by which</p>
HHIP</p>
SNPs have different effects on lung function in males and females will be important for our understanding of lung health and diseases in both sexes.</p>
</p>