Amino Acid Sequence ; Base Sequence ; Child ; Flow Cytometry ; methods ; Genes, X-Linked ; Hematopoietic Stem Cell Transplantation ; Humans ; Lymphocytes ; metabolism ; Lymphohistiocytosis, Hemophagocytic ; diagnosis ; genetics ; therapy ; Lymphoproliferative Disorders ; diagnosis ; genetics ; therapy ; Mutation ; Transplantation, Homologous ; X-Linked Inhibitor of Apoptosis Protein ; deficiency ; genetics ; metabolism

OBJECTIVEX-linked lymphoproliferative disease (XLP), a genetic disorder characterized by immunodeficiency to Epstein-Barr virus (EBV) infection, has been linked to mutations in the SH2D1A gene. XLP patient displays EBV associated fulminant infectious mononucleosis or hemophagocytic lymphohistocytosis, hypogammaglobulinemia or malignant lymphoma. Here we report the clinical features, gene mutation and SAP expression on PBMCs of a Chinese patient with XLP and potential carriers.

METHODA 6 years old male patient and his maternal relatives were enrolled in this study. The patient was found to have with a renal Burkitt lymphoma on the right waist at 5 years of age by accident. His elder brother and a maternally related cousin both died of multiple systemic organ dysfunction syndrome (MODS) due to fulminant infectious mononucleosis (FIM) at the age of one year. The patient and his maternal relatives were subjected to detection of SAP expression on the PBMCs by flow cytometry and gene mutation analysis of SH2D1A by using PCR based on genomic DNA.

RESULTThe patient exhibited 536.9 copy/ml level of circulating EBV-DNA during remission. Sequence analysis showed that the patient harbored a nonsense mutation in exon 2 (C462T), resulting in a premature stop codon (Arg55X). His mother and some of the maternal relatives were proved to be carriers of this mutation. SAP expression from the patient was significantly reduced as compared to normal individual and the carriers.

CONCLUSIONWe identified a Chinese XLP case genetically. Assessment of SAP expression on PBMCs by flow cytometry seemed to be an effective rapid diagnostic method for this disease. Absence of EBV infection does not diminish the possibility of XLP.

Carrier Proteins ; genetics ; Child ; DNA, Viral ; blood ; Epstein-Barr Virus Infections ; complications ; Exons ; Herpesvirus 4, Human ; isolation & purification ; Humans ; Intracellular Signaling Peptides and Proteins ; genetics ; Lymphoproliferative Disorders ; complications ; genetics ; virology ; Male ; Mutation ; Pedigree ; Signaling Lymphocytic Activation Molecule Associated Protein

OBJECTIVEX-linked agammaglobulinemia (XLA) is the most common disorder among primary immunodeficiency diseases, which is caused by mutations in the cytoplasmic Bruton's tyrosine kinase (BTK) gene, characterized by lack of mature, circulating B lymphocytes, hypogammaglobulinemia, and recurrent bacterial infections. Mutations in BTK are highly diverse. In this study, genetic analysis was performed on BTK to realize the feature of gene mutation of XLA in Mainland of China.

METHODSSeven patients from 7 different families were enrolled in the analysis. RT-PCR was employed to reverse transcript total RNA and 8 couples of primers were designed for PCR. PCR products were sequenced and the mutation sites were identified.

RESULTSSeven completely different mutations were identified in the 7 patients. All the 7 mutations located at BTK coding region. Three of the 7 mutations were located in pleckstrin homology functional area, 2 mutations located in BTK area, and in other 2 cases at Src homology 2 and Src homology 3 regions, respectively. The mutations in 2 of 7 cases were in exon 18, and the others were in exon 2, 5, 6, 8 and 10, respectively. The types of mutation included 3 missense (L11P, I590F and Y591S), two nonsense (W281X, and Q234X) mutations resulting in premature stop codons. A 10-base pair nucleotides duplicated insertion located between the nucleotide 596 and 597 resulting in frameshift, and a 8 base pair deletion at the nucleotide position 472 resulting in frameshift. Four of the 7 mutations are novel mutation types and have not been reported. Four of 7 mothers were analyzed, 3 of them were carrier and 1 was normal.

CONCLUSIONThe patients enrolled in this study had classical clinical features of XLA. All the 7 identified mutations located at BTK coding region and 4 of them were novel mutations. Genetic analysis can be used for diagnosis of XLA and distinguish it from other hypogammaglobulinemia.

Adolescent ; Agammaglobulinemia ; diagnosis ; genetics ; Base Sequence ; Child ; China ; Codon, Nonsense ; DNA, Complementary ; Genetic Diseases, X-Linked ; diagnosis ; genetics ; Genotype ; Humans ; Male ; Mutation ; Mutation, Missense ; Protein-Tyrosine Kinases ; genetics ; Reverse Transcriptase Polymerase Chain Reaction ; Young Adult

X-linked severe combined immunodeficiency (X-SCID) is a rare, life-threatening immune disorder, caused by mutations in the gamma c chain gene, which encodes an essential component of the cytokine receptors for interleukin-2 (IL-2), IL-4, IL-7, IL-9, IL-15, and IL-21. A 13-month-old boy with recurrent infections who had reduced serum immunoglobulin levels and decreased numbers of CD3, CD16/56 cells was evaluated for gamma c chain gene mutation and protein expression. The patient had a C-to-T point mutation at nucleotide position 690, one of the hot spots, resulting in a single amino acid substitution of cysteine for arginine (R226C), as determined by direct sequencing and PCR-RFLP. The patient's mother was a heterozygous carrier. Percutaneous umbilical cord blood sampling was performed at the 6-month of gestation in a subsequent pregnancy. As the immunophenotype of the fetus showed an identical pattern, the pregnancy was terminated and genetic analysis of the abortus confirmed recurrence. This is the first report of the molecular diagnosis of X-SCID in Korea. Genetic analysis of the gamma c chain gene is useful for definite diagnosis and genetic counseling for X-SCID.
Arginine/chemistry ; Cysteine/chemistry ; DNA/metabolism ; DNA Mutational Analysis ; Female ; Flow Cytometry ; Genetic Counseling/*methods ; Heterozygote ; Human ; Immunoglobulins/metabolism ; Immunophenotyping/methods ; Korea ; *Linkage (Genetics) ; Male ; *Mutation ; Pedigree ; Point Mutation ; Polymerase Chain Reaction ; Polymorphism, Restriction Fragment Length ; Receptors, Immunologic/*genetics ; Sequence Analysis, DNA ; Severe Combined Immunodeficiency/*diagnosis/*genetics ; Support, Non-U.S. Gov't ; Time Factors ; *X Chromosome

Autoimmune enteropathy (AIE) is a rare disease, characterized by intractable diarrhea, villous atrophy of the small intestine, and the presence of circulating anti-enterocyte autoantibodies. Immune dysregulation, polyendocrinopathy, enteropathy, X-linked (IPEX) syndrome, and mutations in FOXP3, which is a master gene of regulatory T cells (Tregs), are major causes of AIE. Recent studies have demonstrated that mutations in other Treg-associated genes, such as CD25 and CTLA4, show an IPEX-like phenotype. We present the case of a 13-year-old girl with CTLA4 haploinsufficiency, suffering from recurrent immune thrombocytopenic purpura and intractable diarrhea. We detected an autoantibody to the AIE-related 75 kDa antigen (AIE-75), a hallmark of the IPEX syndrome, in her serum. She responded well to a medium dose of prednisolone and a controlled dose of 6-mercaptopurine (6-MP), even after the cessation of prednisolone administration. Serum levels of the soluble interleukin-2 receptor and immunoglobulin G (IgG) were useful in monitoring disease activity during 6-MP therapy. In conclusion, autoimmune-mediated mechanisms, similar to the IPEX syndrome, may be involved in the development of enteropathy in CTLA4 haploinsufficiency. Treatment with 6-MP and monitoring of disease activity using serum levels of soluble interleukin-2 receptor and IgG is suggested for such cases.