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Mafalda Rebelo1, Catarina Martins2, Ana Isabel Cordeiro1, Conceição Neves1, Lamberto Torralba3, Bianca Tesi3, Samuel Chiang4, Yenan Bryceson4, João Farela Neves1


1. Primary Immunodeficiencies Unit, Hospital de Dona Estefânia, Centro Hospitalar de Lisboa Central, EPE, Lisboa;
2. CEDOC - Chronic Diseases Research Center, NOVA Medical School, Lisboa, Portugal
3. Childhood Cancer Research Unit, Karolinska University Hospital Solna, Stockholm, Sweden;
4. Center for Hematology and Regenerative Medicine, Department of Medicine, Karolinska Institutet, Stockholm, Sweden

17th Biennial Meeting of the European Society for Immunodeficiencies (ESID), 2016, 21–24/09/2016, Barcelona, Spain (Poster)

Background: X-linked lymphoproliferative disease (XLP) is a rare primary immunodeficiency characterized by susceptibility to severe EBV infection. XLP-1 is caused by a mutation in SH2D1A which encodes the intracellular adaptor molecular SAP. It regulates signal transduction pathways downstream of the SLAM family of surface receptors to control CD4+ T cell (and B cells), CD8+ T cell and NK cell function. It can present as fulminant HLH, hypogammaglobulinemia, auto-immunity or lymphoproliferation.
Case Presentation: A 14-year-old male with a 4-months history of abdominal pain and weight loss. He presented tenderness in the right lower quadrant. The CT scan and colonoscopy revealed the presence of a vegetant mass in the ileocaecal transition, later characterized as an EBV-positive Burkitt lymphoma. He had an older brother who had died in 1995 at the age of 2 with fulminant EBV-HLH. This prompted investigation of underlying XLP: he had severe hypogammaglobulinemia, he had no switched memory B-cells and no NKT cells, thus allowing a presumptive diagnosis of SAP deficiency (XLP-1). Despite normal SAP expression, as measured by flow-cytometry, sequencing of SH2D1A revealed a hemizygous mutation (c.201G>A). The mutation does not affect the amino acid sequence (p.Glu67Glu), but disrupts a slice site, causing skipping of exon 2. The patient received CHOP therapy directed to Burkitt lymphoma as well as IGIV substitution, while he waits for HSCT.
Conclusion: Recognition by paediatricians of the different phenotypes of XLP is extremely important to allow an early multidisciplinary management of the disease, which is often fatal.

Palavras-chave: XLP, SAP, EBV, Lymphoma, Adolescent