SLC22A5 and asthma: But that is unlikely to be the case for the other three genes, SLC22A5 (organic cation transporter involved in pulmonary absorption of asthma-related drugs76, 77), WDR36 (nucleolar protein involved in processing of 18S rRNA78) and HLA-DQA2 (HLA class II molecule expressed in epidermal Langerhans cells79).