{Reference Type}: Journal Article
{Title}: Novel Mutation in the Moesin (MSN) Gene Leads to Immunodeficiency with Epstein-Barr Virus (EBV) Infection and Dermatomyositis-Like Symptoms.
{Author}: Sun B;Liu L;Han L;Li Q;Wu Q;Hou J;Wang W;Ying W;Zhou Q;Qian F;Lu W;Wang X;Sun J;
{Journal}: J Clin Immunol
{Volume}: 44
{Issue}: 7
{Year}: 2024 Jun 26
{Factor}: 8.542
{DOI}: 10.1007/s10875-024-01755-0
{Abstract}: <B>OBJECTIVE: </B>Moesin (MSN) deficiency is a recently reported combined immunodeficiency, and few cases have been reported to date. We describe a Chinese patient with a novel mutation causing MSN deficiency and a novel phenotype.<BR><B>METHODS: </B>Clinical and immunological data were collected. Whole-exome sequencing was performed to identify gene mutations. MSN protein expression and T cell proliferation and activation were determined by flow cytometry. Cell migration was confirmed with a Transwell assay. Autoantibody levels were analyzed using antigen microarrays.<BR><B>RESULTS: </B>The patient was a 10-year-old boy who presented with recurrent fever, oral ulcers and dermatomyositis-like symptoms, such as periorbital edema, facial swelling, elevated creatine kinase levels, and abnormal electromyography and muscle biopsy results. Epstein-Barr virus (EBV) DNA was detected in the serum, cells and tissues of this patient. He further developed nasal-type NK/T-cell lymphoma. A novel hemizygous mutation (c.68 A > G, p.N23S) in the MSN gene was found. The immunological phenotype of this patient included persistent decreases in T and B lymphocyte counts but normal immunoglobulin IgG levels. The patient had attenuated MSN protein expression and impaired T-cell proliferation and migration. The proportions of Tfh cells and CD21low B cells in the patient were higher than those in the controls. Moreover, 82 IgG and 102 IgM autoantibodies were more abundant in the patient than in the healthy controls.<BR><B>CONCLUSIONS: </B>The novel mutation N23S is pathogenic and leads to a severe clinical phenotype. EBV infection, tumor, and dermatomyositis-like autoimmune symptoms may be associated with MSN deficiency, further expanding the understanding of the disease.