Variation in genes involved in immunity influences children’s susceptibility to developing otitis media, according to research by a US team.
The findings suggest that an inherited susceptibility to otitis media may be modified through behaviours known to boost immunity, such as breastfeeding, say the researchers in PLoS ONE.
Janak Patel (University of Texas Medical Branch, Galveston) and team obtained DNA samples from 653 children aged over 6 months who were classified as either prone or not prone to otitis media based on their clinical history.
Children were assessed for 21 single nucleotide polymorphisms (SNPs) in genes involved in innate or adaptive immunity.
The study found that proneness to otitis media was significantly and independently associated with the Thr280Met SNP in the CX3C chemokine receptor 1 gene, with an adjusted odds ratio (OR) of 6.23 versus the wild-type genotype.
Susceptibility to otitis media was also significantly and independently associated with the simultaneous presence of three factors – the –511 SNP in the interleukin-1β (IL-1β) gene, the –1082 SNP in the interleukin-10 (IL-10) gene, and White race. These factors were not predictive of otitis media when analysed individually.
There were three other significant independent risk factors for proneness to otitis media: a family history of proneness (OR=2.08), daycare attendance (OR=1.68) and not being breastfed (OR=1.46).
A subset of 202 of the children were followed-up prospectively for 1 year for the occurrence of otitis media during episodes of upper respiratory infection (URI). One of the analysed SNPs (–31 in IL-1β) was associated with an increased risk of frequent infections while four SNPs (–592 in IL-10, –511 in IL-1β, –746 in IL-5 and –251 in IL-8) were associated with a decreased risk.
Furthermore, the risk of developing otitis media during URI was lower in children who were homozygous for the –592 SNP in IL-10. As before, family history and daycare attendance modified this risk.
Taken together, the findings suggest that specific SNPs in immunoregulatory genes have a role in either promoting or protecting against URI and otitis media in children, say the authors.
“Currently, as none [of] the SNP tests are available for routine clinical use, they cannot be used to guide patients for their individual risk,” the researchers note, but add: “[O]ur study suggests that change in behavior such as increasing breastfeeding may be beneficial for disease reduction regardless of inheritance of disease susceptible genes.”
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