INTRODUCTION
Allergic rhinitis (AR) is an immunoglobulin E (IgE)-mediated
inflammatory condition, which occurs in the nose with symptoms, such as
nasal obstruction, watery rhinorrhea, itching, and sneezing. Following a
global trend, in Korea, the prevalence of AR among children, adults, and
the elderly has also increased rapidly over the past few
decades.1-3 Various
environmental factors, such as indoor allergens, air pollution, exposure
to certain drugs during pregnancy, and factors affecting the microbiome
based on hygiene hypotheses have been mentioned as the causes of
increase in AR.4-7
The number of siblings may affect the development of hay fever and
eczema, which suggests that changes in hygienic environmental factors
during early childhood may cause an increase in allergic
diseases.4,6-10In the past few decades, in Korea, hygienic environmental factors have
drastically changed due to rapid westernization and industrialization,
and children have been exposed to various
environments.7,11Therefore, it is appropriate to explain the development of allergic
diseases as a result of the combined effects of various environmental
factors, rather than one environmental factor.
Recently, attempts to identify the association between genetic factors
and prevalence of AR have increased. In recent studies, the A allele of
interleukin-13 (IL-13) single nucleotide polymorphism, rs20541, is
associated with the risk of AR in
Asians.1,12Additionally, we previously
reported the association between AR and
Toll-like receptor 4 (TLR4)
(rs1927911)/cluster of differentiation 14 (CD14) (rs2569190), which are
receptors that enable response to microbes or cause tissue
damage.13,14Glutathione S-transferase P1 (GSTP1) (rs1695) modulates the effect of
environment-induced respiratory symptoms in
children.15,16Studies on various genes have revealed the possibility that the
development of AR is affected by multiple
genes.1,13,17,18However, there are few studies on the combined effect of multiple genes
on the development of AR.
Studies on environmental risk score (ERS) have been initiated to
identify the effect of various environmental factors on the risk of
developing chronic diseases, such as cardiovascular disease and diabetes
mellitus.19,20The concept of polygenic risk score (PRS) is based on the assumption
that even though a single genetic variant has an insignificant effect on
the development of chronic disease, a combination of multiple genetic
variants may exert a polygenic effect that increases disease risk,
including allergic
diseases.18,21,22
However, there are no studies on
gene-environment interactions using ERS and PRS in children with AR.
Therefore, we investigated the combined effect of early life hygienic
ERS and PRS on the development of AR in school-age children.