||if 4 years old or younger, ~2.5x increased asthma risk if exposed to smoke
rs4795400 is one of several SNPs from a region on chromosome 17q21 that has been linked to risk for asthma.
A total of 651 French patients with asthma, from among 1,621 subjects in 388 families, were analyzed for SNPs in the (17q21) region. An association was found between this SNP and early-onset asthma (but not with later onset asthma) which was significant after correction at p < 0.001. Upon further study, this association was seen primarily only in children exposed to tobacco smoke. The odds ratio was 2.5, based on the most likely assumption that this risk is associated only with the recessive homozygous state (and not the heterozygous state, which is still possible). [PMID 18923164]
[PMID 22370936] Genetic variants on 17q21 are associated with asthma in a Han Chinese population