X-Linked Lymphoproliferative Disease With a Novel SH2D1A Gene Mutation To the Editor: X-linked lymphoproliferative disease (XLP, OMIM 308240) is a rare inherited immunodeficiency characterized by extreme vulnerability to Epstein-Barr virus (EBV) infection, which may lead to severe or fatal mononucleosis, acquired hypogammaglobulinaemia, malignant B-cell lymphoma and aplas- tic anemia [1]. The SH2D1A gene responsible for XLP maps to the X-chromosome (Xq25) [2]. The protein contains 128 amino acids, with one src homology 2 (SH2). Conserved SH2 domain interacts with signaling lymphocyte-activating molecule (SLAM) and other molecules required for a controlled T-cell response during EBV infection [3,4]. In the absence of functional SLAM activating protein, associated receptors may not signal properly, compromis- ing the control of EBV infected B-lymphocytes and facilitating the secondary expansion of T lymphocytes and macrophages. Several classes of SH2D1A mutations (63 in total [5]) have been identified in XLP patients so far, most of them in the SH2 domain [6]. A3 1 2 years old male was admitted for work-up of fever of unknown origin. On admission, hepatosplenomegaly, lymphadeno- pathy and thrombocytopenia were noted. Liver biopsy revealed hepatitis, with predominantly lymphocytic infiltration and erythro- phagocytosis in Kupffner cells. EBV- RNA was detected in portal zone lymphocytes. RT- PCR demonstrated copies of EBVin serum, while IgM and IgG anti EBV-VCA, IgG anti EBNA and IgG anti EA were negative. Two maternal uncles died in infancy with similar clinical picture, so diagnosis of XLP was suggested. Despite dexamethasone and VP-16 therapy, condition deterio- rated and a bone marrow transplant with a reduced conditioning regimen was performed three weeks after the initial admission. The patient died from multiorgan failure five days after transplantation. The whole SH2D1A gene was PCR amplified and directly sequenced. The mutation (G ! A) found in the proband changes the last nucleotide (201) in exon 2 and is named 201G > A. The transversion does not result in an amino acid sequence change (GAG > GAA, Glutamine), but rather changes the donor splice site (splice site AGgt > AAgt). The patient’s mother and twin sister were confirmed to be heterozygous for this particular mutation. RT-PCR analysis showed 190 bp product in normal controls, whereas mother had 2 amplicons, a normal 190 bp and an additional 127 bp amplicon. The analysis confirmed the disruption of the splicing mechanism resulting in shorter mRNA missing the entire exon 2. The mutation 201G > A at the end of exon 2, changes the donor splice site of exon 2. In consequence, the splicing mechanism is unable to recognize the changed sequence and intron 1, exon 2 and intron 2 are excised in from pre-mRNA. cDNA analysis confirmed the deletion of the exon 2 (63 bp). Exon 2 of the SH2D1A gene encodes 20 amino acids of the SH2 domain. This mutation results in loss of SH2D1A function and the clinical XLP phenotype. Sixty- three different mutations in the SH2D1A gene have been reported so far, nine of them involved in splicing [5]. Boys with a family history of XLP should be routinely tested for mutations in the SH2D1A gene. Due to the high rate of complications and patients mortality when attempting the trans- plantation after EBV infection, the decision whether to transplant prior to EBV infection should be carefully considered, if a mutation is found [7]. ACKNOWLEDGMENT The study was supported in part by The Slovenian Ministry of Education, Science and Sport grants J3-3096, J3-6072. Marus ˇa Debeljak, PhD Katarina Trebus ˇak Podkrajs ˇek, PhD Centre for Medical Genetics University Children’s Hospital Ljubljana, Slovenia Richard Aplenc, MD, MSCE Pediatric Oncology/Stem Cell Transplant Children’s Hospital of Philadelphia, Philadelphia Janez Jazbec, MD, PhD* Hematology and Oncology Unit University Children’s Hospital Ljubljana, Slovenia REFERENCES 1. Purtilo DT, Cassel CK, Yang JP, et al. X-linked recessive progressive combined variable immunodeficiency (Duncan’s disease). Lancet 1975;7913:935–940. 2. Coffey AJ, Brooksbank RA, Brandau O, et al. Host response to EBV infection in X-linked lymphoproliferative disease results from mutations in an SH2-domain encoding gene. Nat Genet 1998;20: 129–135. 3. Sayos J, Wu C, Morra M, et al. The X-linked limphoprolipherative- disease gene product SAP regulates signals induced through the co- receptor SLAM. Nature 1998;395:462–469. 4. Tangye SG, Lazetic S,Woollatt E, et al. Cutting edge: human 2B4, an activating NK cell receptor, recruits the protein Tyrosine phospha- tase SHP-2 and the adaptor signaling protein SAP. J Immunol 1999;162:6981–6985. 5. http://www.hgmd.cf.ac.uk/ac/index.php 6. Mrra M, Simarro-Grande M, Martin M, et al. Characterisation of SH2D1A missense mutations identified in X-linked Lymphoproli- ferative Disease Patients. J Biol Chem 2001;276:36809–36816. 7. Lankester AC, Visser LF, Hartwig NG, et al. Allogeneic stem cell transplantation in X-linked lymphoproliferative disease: two cases in one family and review of the literature. Bone Marrow Transplant 2005;36:99–105. ß 2007 Wiley-Liss, Inc. DOI 10.1002/pbc.21216 —————— Grant sponsor: Slovenian Ministry of Education, Science and Sport; Grant numbers: J3-3096, J3-6072. *Correspondence to: Janez Jazbec, University Children’s Hospital, Ljubljana, Vrazov trg 1, SI-1000 Ljubljana, Slovenia. E-mail: janez.jazbec@mf.uni-lj.si Received 23 January 2007; Accepted 21 February 2007 Letters to the Editor 187