Maternal onset de novo SH2D1A mutation and lymphocytic choriomeningitis virus infection in a patient with X-linked lymphoproliferative disease type 1: A case report

X-linked lymphoproliferative disease type 1 (XLP1) is a rare genetic immunodeficiency disease, which occurs due to germline mutations in the SH2D1A gene. This gene has been reported to encode the adaptor molecule signaling lymphocytic activation molecule-associated protein XLP1 is generally triggered by the Epstein-Barr virus (EBV) infection. The present study reported the case of a 4-year-old male who presented with a high fever, hypogammaglobulinemia, diffuse lung disease and encephalitis. The patient was infected with the lymphocytic choriomeningitis virus (LCMV), not EBV or any other human herpes virus. The patient was found to carry a SH2D1A c.7G>T/p.A3S mutation, which was inherited from the mother and maternal grandfather, as well as a SH2D1A c.228T>A/p.Y76X mutation, which was identified to be a maternal-onset de novo mutation at the time of germline development of the patient's mother. To the best of our knowledge, the present study is the first reported case of maternal-onset XLP1 with a de novo SH2D1A mutation and LCMV infection.