title: Clinical and molecular characteristics of Chinese patients with X-linked lymphoproliferative syndrome type 1.
abstract: BACKGROUND
  X-linked lymphoproliferative syndrome type 1 (XLP1) is a rare inherited, life-threatening immunodeficiency disorder caused by mutations in SH2D1A gene. It affect approximately two to three males per million. Fewer than 10 cases with definite gene mutations have been reported in Chinese mainland and no rapid diagnosis method has been established.
  
  
  METHODS
  We determined the clinical and molecular characteristics of five patients with XLP1. The SH2D1A gene were amplified by PCR and sequenced, the SAP expression was analyzed by flow cytometry.
  
  
  RESULTS
  Two patients had novel SH2D1A mutations and three had mutations that have been previously reported. Three patients presented with fulminant infectious mononucleosis or hemophagocytic lymphohistiocytosis and one presented with lymphoma. Null or decreased SAP expression on PBMCs was noted. The remaining patient presented with unique, recurrent, nonfulminant infectious mononucleosis and bimodal intracellular SAP protein expression.
  
  
  CONCLUSIONS
  The overall molecular characteristics and clinical phenotypes of Chinese patients with XLP1 matched previous reports. The unique bimodal intracellular SAP protein expression indicated the presence of some residual SAP-positive T cells that are able to respond to persistent Epstein-Barr virus infection and could explain the relatively mild clinical phenotype of this patient.
authors.affiliation: Ministry of Education Key Laboratory of Child Development and Disorders, Children's Hospital of Chongqing Medical University, Chongqing, China; Division of Immunology, Children's Hospital of Chongqing Medical University, Chongqing, China.
authors.forename: Yun-Fei
authors.initials: YF
authors.lastname: An
authors.forename: Xiao-Bo
authors.initials: XB
authors.lastname: Luo
authors.forename: Xi
authors.initials: X
authors.lastname: Yang
authors.forename: Jing
authors.initials: J
authors.lastname: Wang
authors.forename: Li
authors.initials: L
authors.lastname: Li
authors.forename: Xiao-Dong
authors.initials: XD
authors.lastname: Zhao
mesh_terms: D002675:Child, Preschool; D005434:Flow Cytometry; D006801:Humans; D007223:Infant; D047908:Intracellular Signaling Peptides and Proteins / Q000235:genetics*; D008232:Lymphoproliferative Disorders / Q000235:genetics*; D008297:Male; D000071179:Signaling Lymphocytic Activation Molecule Associated Protein
chemical_list: D047908:Intracellular Signaling Peptides and Proteins; C114953:SH2D1A protein, human; D000071179:Signaling Lymphocytic Activation Molecule Associated Protein
keywords: X-linked lymphoproliferative syndrome; mild clinical phenotype; primary immunodeficiency; residual SAP expression