Case Report: Meningoencephalitis With Thrombotic Occlusive Vasculopathy in a Young EBV-Naïve Boy Is Associated With a Novel SH2D1A Mutation

<jats:p>X-linked lymphoproliferative disease (XLP1) is a combined immunodeficiency characterized by severe immune dysregulation caused by mutations in the <jats:italic>SH2D1A/SAP</jats:italic> gene. Loss or dysfunction of SH2D1A is associated with the inability in clearing Epstein-Barr-Virus (EBV) infections. Clinical manifestation is diverse and ranges from life-threatening hemophagocytic lymphohistiocytosis (HLH) and fulminant infectious mononucleosis (FIM) to lymphoma and antibody deficiency. Rare manifestations include aplastic anemia, chronic gastritis and vasculitis. Herein, we describe the case of a previously healthy eight-year old boy diagnosed with XLP1 presenting with acute non-EBV acute meningoencephalitis with thrombotic occlusive vasculopathy. The patient developed multiple cerebral aneurysms leading to repeated intracerebral hemorrhage and severe cerebral damage. Immunological examination was initiated after development of a susceptibility to infections with recurrent bronchitis and one episode of severe pneumonia and showed antibody deficiency with pronounced IgG1-3-4 subclass deficiency. We could identify a novel hemizygous <jats:italic>SH2D1A</jats:italic> point mutation affecting the start codon. Basal levels of SAP protein seemed to be detectable in CD8<jats:sup>+</jats:sup> and CD4<jats:sup>+</jats:sup> T- and CD56<jats:sup>+</jats:sup> NK-cells of the patient what indicated an incomplete absence of SAP. In conclusion, we could demonstrate a novel <jats:italic>SH2D1A</jats:italic> mutation leading to deficient SAP protein expression and a rare clinical phenotype of non-EBV associated acute meningoencephalitis with thrombotic occlusive vasculopathy.</jats:p>