A NOVEL MUTATION OF IL21R IN A PATIENT WITH COMMON VARIABLE IMMUNODEFICIENCY

Abstract

<h3>Introduction</h3> Interleukin-21 (IL21) and its receptor (IL21R) are involved in activation of the JAK/STAT pathway and are necessary for B-Cell differentiation. Common variable immunodeficiency (CVID) is a disorder where the patient has hypogammaglobulinemia. There is a growing number of mutations associated with this disease, and we present a novel heterozygous IL21R mutation in a patient with CVID. <h3>Case Description</h3> We report a 70-year-old male patient with diagnosed CVID based on clinical symptomology. The patient had diminished serum antibody levels: IgG (383 mg/dL; normal: 600-11450 mg/dL), IgM (36 mg/dL; normal: 50-300 mg/dL), and IgA (43 mg/dL; normal: 70-320 mg/dL) along with abnormal lymphocyte markers showing low CD19 (26 cells/uL; normal: 110-660 cells/uL), CD3 (538 cells/uL; normal: 840-3060 cells/uL), CD4 (425 cells/uL; normal: 490-1740 cells/uL), CD8 (129 cells/uL; normal: 180-1170 cells/uL) levels. Genetic evaluation was performed by Invitae^TM genomic hybridization-based protocol with Illumina sequencing technology. A mutation, a heterozygous mutation of IL21R c.615G>C (p.Met205Ile) on exon 6 was found. A second heterozygous mutation, DOCK8 c.494C>T (p.Ser165Leu), was also found. <h3>Conclusion</h3> IL21R is largely expressed in the spleen and the thymus and are important in adaptive immunity. Mutations in IL21R have been reported prior in patients with CVID, but none on exon 6. We report a novel mutation of the IL21R in a patient with CVID.