Gene variants relate to risk of respiratory infections and AOM

Certain polymorphisms in mannose-binding lectin (MBL) and toll-like receptors (TLRs), genes that have a role in the innate immune system, promote susceptibility to or protection against respiratory and rhinovirus infections and acute otitis media (AOM), according to a study in Finnish infants.

Researchers followed 923 children from birth to age 2 years for respiratory infections, relying primarily on daily parental diaries. When respiratory symptoms developed, investigators obtained nasal swabs, on which polymerase chain reaction and antigen tests were performed to detect respiratory viruses. Nasal swabs also were collected during scheduled visits at 2, 13, and 24 months, and blood samples were obtained when the infants were 2 months old. Investigators recorded almost 4000 episodes of acute respiratory infections, with rhinovirus the sole agent in 59%.

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Of the study children, about one-third had variant types of MBL; more than half had variants of TLR3 and TLR8, with smaller proportions having variants of TLR2, TLR4, and TLR7. The MBL polymorphisms were associated with an increased number of days per year with symptoms of respiratory infection and with an increased risk of rhinovirus-associated AOM. The TLR8 polymorphisms were tied to an increased risk of recurrent rhinovirus and the TLR2 variants with recurrent AOM, whereas TLR7 polymorphisms decreased the risk of recurrent rhinovirus infections (Toivonen L, et al. Pediatr Infect Dis J. 2017;36[5]:e114-e122).

Thoughts from Dr Burke

Dr Barton Childs, the late, legendary Johns Hopkins geneticist, was well known for asking at every case conference: “Why does this child have this condition at this time?” Studies like this one bring us closer to being able to answer Dr Childs’ question.