Screening for genetic polymorphisms of histamine H1 and NK1 receptors which are involved in development of hyperreactivity of the nose

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We screened for genetic polymorphisms of histamine H1 and substance P (NK1) receptors which are involved in development of hyperreactivity of the nose. For this study we enrolled 48 patients who met one of the following criteria : (1) one who has IgE specific for an allergen (s), but lacks hyperreactive nasal symptoms, (2) one who has IgE specific for an allergen (s) and hyperreactive nasal symptoms, i.e. nasal allergy, (3) one who is negative for IgE specific for an allergen (s), but has hyperreactive nasal symptoms, i.e. vasomotor rhinitis. The numbers of patients were (1) 23, (2) 20, and (3) 5. DNA was extracted from their blood after an informed consent was obtained, and subjected to analysis of genetic polymorphisms in the coding regions of those genes. The combination of polymerase chain reaction (PCR) and single strand comformation polymorphism (SSCP) analysis allowed us to identify a polymorphism of H1 receptor gene at a codon 349 (GAT*CAT,Asp349*His349) in a patient in the group (l). She had the polymorphism in a heterogenous manner. Although it may contribute to hyporeactivity of the nose in the patient, the significance of the polymorphism was considered still little for its low frequency in the population. In terms of NK1 receptor gene, two silent mutations were identified in exonsl and 5, respectively. The former was at a codon 111(TTC*TTT,Phe111), and the latter was at codon 378 (TCG*TCA,Ser378). Because these genetic polymorphisms do not change the structure of NK1 receptor, they have no significance in the pathogenesis of nasal hyperreactivity of the nose. Another study to screen for a mutation in the promoter regions of those genes will be performed hereafter