Table 3.

Combined effects of gene-environmental interactions.

Gene	Study Design	Race	SNP	Allele	Association	Ref
FOXP3	Candidate gene	Brazilian	rs2232368	C/T	Associated with asthma susceptibility and onset of atopy in females.	[139]
TGF-B1	Candidate gene	Mixed	rs4803457	C/T	-509TT genotype carriers have higher susceptibility to early-onset childhood asthma	[137]
GSTP1	Candidate gene	Canadian, Swedish, German, Netherlands (six birth cohorts)	rs1138272	C/T	Minor allele carriers with NO2 exposure have higher risk to current asthma, ever asthma, and injury from air pollution compared to major allele carriers	[131]
			rs1695	A/G*	Minor allele carriers for both rs1138272 and rs1695 exposed to traffic and NO2 may be at an increased risk of asthma, current asthma, and ever asthma. *A/A genotype has protective properties against complications from household allergens, G allele makes asthmatics more prone to complications	[131,132]
NFE2L2	Candidate gene	Hungarian	rs2588882	T/G	Protective effect during infection-induced exacerbation in asthmatics [IIA]	[148]
			rs6721961	G/T
TLR2	Candidate gene	Netherlands	rs4696480	T/A	Modifies effect of exposure of air pollution on asthma from birth to 8 years of age	[134]
			rs1898830	A/G
TLR4	Candidate gene	Netherlands	rs2770150	A/G	Modify the effect of exposure to air pollution on asthma	[134]
			rs10759931	G/A
			rs6478317	A/G
			rs1927911	C/A
ORMDL3	Candidate gene	Danish, delivered in Copenhagen	rs7216389	T/C	Significant association with risk of recurrent wheeze in homozygous variant allele carriers	[143]
IL9	GWAS	Mixed	rs11741137	C/T	Significant interactions of the rs11741137, rs2069885, and rs1859430 SNPs with dust mite allergen exposure. Increase in the likelihood of exacerbation for dominant genotype carriers [rs11741137, rs2069885] and with increased dust mite exposure	[141]
			rs2069885	G/A
			rs1859430	G/A
P2RY12	Candidate gene	Mixed	rs8180086	G/A	Modified airway hyperresponsiveness values with HDM exposure	[145]
			rs3732765	G/A
			rs10935840	A/G
			rs11708767	G/A
			rs7615865	A/T	Modified bronchodilator reversibility with HDM exposure
			rs1491978	G/C
IL6		Chinese	rs1800795	G/C	Gene-smoking environmental interaction increases risk of asthma	[149]
IL1RN	Candidate gene	Mixed [150] or Caucasian [151]	rs2234678	A/G	Protective properties in the development of asthma in those without childhood environmental tobacco exposure; those with childhood exposure, were at higher risk of early onset asthma. Maternal smoking during pregnancy in infants with the GG genotype had increased susceptibility to repeated asthma and persistent asthma in children	[150,151]