Hence, in our study, we included the HTR2A (rs6314 and rs6313) and HTR2C (rs3813929 and rs518147) polymorphisms with the hypothesis that they could influence the expression of 5-HT2A and 5-HT2C receptors in both respiratory system and platelets and might be associated with asthma by influencing the unbound 5-HT levels. This evidence concerns the gene HTR2A and asthma.