A Novel Mutation in the IL6R Gene Identified in a Family with Asthma Patients

Background: Allergic diseases, including asthma, atopic dermatitis, allergic rhinitis, and food allergies, are caused by both environmental and genetic factors. The allergic condition, where genetic factors make up the largest proportion (up to 95%), is asthma. Aim: To identify polymorphisms and mutations in potentially disease-causing genes in a family affected with allergic asthma. Methods: Whole exome sequencing of the index patient was performed via next-generation sequencing. Variants in known allergy-associated susceptibility genes were identified by comparison with the reference genome GRChr37. Results: Seven common polymorphisms and three rare mutations were identified in the allergy-susceptibility genes of the index patient. Only four of these variants co-segregated with the second patient of the same family. These variants occurred in the TENS1, NPSR1, RAD50, and IL6R genes. Discussion: The variants observed in TENS1 and NPSR1 are relatively common (minor allele frequency, MAF ∼0.4), whereas the mutation in RAD50 is rare (MAF 0.0035). The mutation identified in IL6R (S409P) has never been found before. IL6R encodes an important receptor of the inflammatory system. The mutation occurs in the intracellular domain within a tyrosine-based motif, which is required for sorting of the IL6R protein to the basolateral side of polarized cells. It is likely that this rare mutation contributes-together with the other variants-to the predisposition to asthma and other allergic diseases.

Keywords: IL6R; allergic rhinitis; allergy; asthma; atopic dermatitis; interleukin-6.