Publications by authors named "Jacob Rozmus"

28 Publications

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Successful rescue transplant for children with primary graft failure using early intervention with a single day preparative regimen and related haploidentical donor.

Bone Marrow Transplant 2021 Apr 29. Epub 2021 Apr 29.

Division of Pediatric Hematology, Oncology and BMT, Department of Pediatrics, BC Children's Hospital, University of British Columbia, Vancouver, BC, Canada.

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http://dx.doi.org/10.1038/s41409-021-01309-7DOI Listing
April 2021

Monogenic Immune Diseases Provide Insights Into the Mechanisms and Treatment of Chronic Graft-Versus-Host Disease.

Authors:
Jacob Rozmus

Front Immunol 2020 4;11:574569. Epub 2021 Feb 4.

Division of Pediatric Hematology, Oncology & BMT, Department of Pediatrics, BC Children's Hospital, University of British Columbia, Vancouver, BC, Canada.

Chronic graft-versus-host disease (GvHD) has become a leading cause of morbidity and mortality following allogeneic hematopoietic stem cell transplantation (HSCT) and can burden patients with devastating and lifelong health effects. Our understanding of the pathogenic mechanisms underlying chronic GvHD remains incomplete and this lack of understanding is reflected by lack of clear therapeutic approaches to steroid refractory disease. Observations predominantly from mouse models and human correlative studies currently support a three phase model for the initiation and development of chronic GvHD: 1) early inflammation and tissue damage triggers the innate immune system. This leads to inflammatory cytokine/chemokine patterns that recruit effector immune cell populations; 2) chronic inflammation causes the loss of central and peripheral tolerance mechanisms leading to emergence of pathogenic B and T cell populations that promote autoimmune and alloimmune reactions; 3) the dysregulated immunity causes altered macrophage polarization, aberrant tissue repair leading to scarring and end organ fibrosis. This model has led to the evaluation of many new therapies aimed at limiting inflammation, targeting dysregulated signaling pathways and restoring tolerance mechanisms. However, chronic GvHD is a multisystem disease with complex clinical phenotypes and it remains unclear as to which cluster of patients will respond best to specific therapeutic strategies. However, it is possible to gain novel insights from immune-related monogenic diseases. These diseases either share common clinical manifestations, replicate steps from the three phase chronic GvHD model or serve as surrogates for perfectly targeted drugs being investigated in chronic GvHD therapy. In this review, we will summarize the evidence from these monogenic immune related diseases that provide insight into pathogenic pathways in chronic GvHD, rationales for current therapies and novel directions for future drug discovery.
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http://dx.doi.org/10.3389/fimmu.2020.574569DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7889949PMC
February 2021

Idiopathic splenomegaly in childhood and the spectrum of RAS-associated lymphoproliferative disease: a case report.

BMC Pediatr 2021 Jan 21;21(1):45. Epub 2021 Jan 21.

Department of Pediatrics, British Columbia Children's Hospital, The University of British Columbia, 950 West 28th Avenue, V5Z 4H4, Vancouver, BC, Canada.

Background: KRAS (KRAS proto-oncogene, GTPase; OMIM: 190,070) encodes one of three small guanosine triphosphatase proteins belonging to the RAS family. This group of proteins is responsible for cell proliferation, differentiation and inhibition of apoptosis. Gain-of-function variants in KRAS are commonly found in human cancers. Non-malignant somatic KRAS variants underlie a subset of RAS-associated autoimmune leukoproliferative disorders (RALD). RALD is characterized by splenomegaly, persistent monocytosis, hypergammaglobulinemia and cytopenia, but can also include autoimmune features and lymphadenopathy. In this report, we describe a non-malignant somatic variant in KRAS with prominent clinical features of massive splenomegaly, thrombocytopenia and lymphopenia.

Case Presentation: A now-11-year-old girl presented in early childhood with easy bruising and bleeding, but had an otherwise unremarkable medical history. After consulting for the first time at 5 years of age, she was discovered to have massive splenomegaly. Clinical follow-up revealed thrombocytopenia, lymphopenia and increased polyclonal immunoglobulins and C-reactive protein. The patient had an unremarkable bone marrow biopsy, flow cytometry showed no indication of expanded double negative T-cells, while malignancy and storage disorders were also excluded. When the patient was 8 years old, whole exome sequencing performed on DNA derived from whole blood revealed a heterozygous gain-of-function variant in KRAS (NM_004985.5:c.37G > T; (p.G13C)). The variant was absent from DNA derived from a buccal swab and was thus determined to be somatic.

Conclusions: This case of idiopathic splenomegaly in childhood due to a somatic variant in KRAS expands our understanding of the clinical spectrum of RAS-associated autoimmune leukoproliferative disorder and emphasizes the value of securing a molecular diagnosis in children with unusual early-onset presentations with a suspected monogenic origin.
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http://dx.doi.org/10.1186/s12887-021-02508-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7819237PMC
January 2021

"Age Related Differences in the Biology of Chronic Graft-Versus-Host Disease After Hematopoietic Stem Cell Transplantation".

Front Immunol 2020 16;11:571884. Epub 2020 Oct 16.

Michael Cuccione Childhood Cancer Research Program, British Columbia Children's Hospital, University of British Columbia, Vancouver, BC, Canada.

It is established that pediatric hematopoietic stem cell transplant (HSCT) recipients have a lower rate of chronic graft-versus-host disease (cGvHD) compared to adults. Our group has previously published immune profiles changes associated with cGvHD of clinically well-defined adult and pediatric HSCT cohorts. Since all analyses were performed by the same research group and analyzed using identical methodology, we first compared our previous immune profile analyses between adults and children. We then performed additional analyses comparing the T cell populations across age groups, and a sub-analysis of the impact of the estimated pubertal status at time of HSCT in our pediatric cohort. In all analyses, we corrected for clinical covariates including total body irradiation and time of onset of cGvHD. Three consistent findings were seen in both children and adults, including elevations of ST2 and naive helper T (Th) cells and depression of NK cells. However, significant differences exist between children and adults in certain cytokines, B cell, and T populations. In children, we saw a broad suppression of newly formed B (NF-B) cells, whereas adults exhibited an increase in T1-CD21 B cells and a decrease in T1-CD24CD38 B cells. Prepubertal children had elevations of aminopeptidase N (sCD13) and ICAM-1. T abnormalities in children appeared to be primarily in memory T cells, whereas in adults the abnormalities were in naïve T cells. In adults, the loss of PD1 expression in naïve T and naïve Th cells was associated with cGvHD. We discuss the possible mechanisms for these age-related differences, and how they might theoretically impact on different therapeutic approaches to cGvHD between children and adults.
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http://dx.doi.org/10.3389/fimmu.2020.571884DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7641628PMC
October 2020

Excellent outcomes following hematopoietic cell transplantation for Wiskott-Aldrich syndrome: a PIDTC report.

Blood 2020 06;135(23):2094-2105

Division of Pediatric Hematology/Oncology, Primary Children's Hospital, University of Utah School of Medicine, Salt Lake City, UT.

Wiskott-Aldrich syndrome (WAS) is an X-linked disease caused by mutations in the WAS gene, leading to thrombocytopenia, eczema, recurrent infections, autoimmune disease, and malignancy. Hematopoietic cell transplantation (HCT) is the primary curative approach, with the goal of correcting the underlying immunodeficiency and thrombocytopenia. HCT outcomes have improved over time, particularly for patients with HLA-matched sibling and unrelated donors. We report the outcomes of 129 patients with WAS who underwent HCT at 29 Primary Immune Deficiency Treatment Consortium centers from 2005 through 2015. Median age at HCT was 1.2 years. Most patients (65%) received myeloablative busulfan-based conditioning. With a median follow-up of 4.5 years, the 5-year overall survival (OS) was 91%. Superior 5-year OS was observed in patients <5 vs ≥5 years of age at the time of HCT (94% vs 66%; overall P = .0008). OS was excellent regardless of donor type, even in cord blood recipients (90%). Conditioning intensity did not affect OS, but was associated with donor T-cell and myeloid engraftment after HCT. Specifically, patients who received fludarabine/melphalan-based reduced-intensity regimens were more likely to have donor myeloid chimerism <50% early after HCT. In addition, higher platelet counts were observed among recipients who achieved full (>95%) vs low-level (5%-49%) donor myeloid engraftment. In summary, HCT outcomes for WAS have improved since 2005, compared with prior reports. HCT at a younger age continues to be associated with superior outcomes supporting the recommendation for early HCT. High-level donor myeloid engraftment is important for platelet reconstitution after either myeloablative or busulfan-containing reduced intensity conditioning. (This trial was registered at www.clinicaltrials.gov as #NCT02064933.).
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http://dx.doi.org/10.1182/blood.2019002939DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7273831PMC
June 2020

A Germline Mutation in the C2 Domain of PLCγ2 Associated with Gain-of-Function Expands the Phenotype for PLCG2-Related Diseases.

J Clin Immunol 2020 02 19;40(2):267-276. Epub 2019 Dec 19.

Michael Cuccione Childhood Cancer Research Program, BC Children's Hospital Research Institute, Vancouver, Canada.

We report three new cases of a germline heterozygous gain-of-function missense (p.(Met1141Lys)) mutation in the C2 domain of phospholipase C gamma 2 (PLCG2) associated with symptoms consistent with previously described auto-inflammation and phospholipase Cγ2 (PLCγ2)-associated antibody deficiency and immune dysregulation (APLAID) syndrome and pediatric common variable immunodeficiency (CVID). Functional evaluation showed platelet hyper-reactivity, increased B cell receptor-triggered calcium influx and ERK phosphorylation. Expression of the altered p.(Met1141Lys) variant in a PLCγ2-knockout DT40 cell line showed clearly enhanced BCR-triggered influx of external calcium when compared to control-transfected cells. Our results further expand the molecular basis of pediatric CVID and phenotypic spectrum of PLCγ2-related defects.
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http://dx.doi.org/10.1007/s10875-019-00731-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7086538PMC
February 2020

Malt1 deficient mice develop osteoporosis independent of osteoclast-intrinsic effects of Malt1 deficiency.

J Leukoc Biol 2019 10 16;106(4):863-877. Epub 2019 Jul 16.

Department of Pediatrics, Division of Gastroenterology, the University of British Columbia, Vancouver, British Columbia, Canada.

This study tested the hypothesis that mucosa associated lymphoid tissue 1 (Malt1) deficiency causes osteoporosis in mice by increasing osteoclastogenesis and osteoclast activity. A patient with combined immunodeficiency (CID) caused by MALT1 deficiency had low bone mineral density resulting in multiple low impact fractures that was corrected by hematopoietic stem cell transplant (HSCT). We have reported that Malt1 deficient Mϕs, another myeloid cell type, are hyper-responsive to inflammatory stimuli. Our objectives were to determine whether Malt1 deficient mice develop an osteoporosis-like phenotype and whether it was caused by Malt1 deficiency in osteoclasts. We found that Malt1 deficient mice had low bone volume by 12 weeks of age, which was primarily associated with reduced trabecular bone. Malt1 protein is expressed and active in osteoclasts and is induced by receptor activator of NF-κB ligand (RANKL) in preosteoclasts. Malt1 deficiency did not impact osteoclast differentiation or activity in vitro. However, Malt1 deficient (Malt1 ) mice had more osteoclasts in vivo and had lower levels of serum osteoprotegerin (OPG), an endogenous inhibitor of osteoclastogenesis. Inhibition of Malt1 activity in Mϕs induced MCSF production, required for osteoclastogenesis, and decreased OPG production in response to inflammatory stimuli. In vitro, MCSF increased and OPG inhibited osteoclastogenesis, but effects were not enhanced in Malt1 deficient osteoclasts. These data support the hypothesis that Malt1 deficient mice develop an osteoporotic phenotype with increased osteoclastogenesis in vivo, but suggest that this is caused by inflammation rather than an effect of Malt1 deficiency in osteoclasts.
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http://dx.doi.org/10.1002/JLB.5VMA0219-054RDOI Listing
October 2019

Tumor Variant Identification That Accounts for the Unique Molecular Landscape of Pediatric Malignancies.

JNCI Cancer Spectr 2018 Oct 25;2(4):pky079. Epub 2019 Jan 25.

Department of Pediatrics, University of British Columbia, Vancouver, BC, Canada.

Precision oncology trials for pediatric cancers require rapid and accurate detection of genetic alterations. Tumor variant identification should interrogate the distinctive driver genes and more frequent copy number variants and gene fusions that are characteristics of pediatric tumors. Here, we evaluate tumor variant identification using whole genome sequencing (n = 12 samples) and two amplification-based next-generation sequencing assays (n = 28 samples), including one assay designed to rapidly assess common diagnostic, prognostic, and therapeutic biomarkers found in pediatric tumors. Variant identification by the three modalities was comparable when filtered for 151 pediatric driver genes. Across the 28 samples, the pediatric cancer-focused assay detected more tumor variants per sample (two-sided, <.05), which improved the identification of potentially druggable events and matched pathway inhibitors. Overall, our data indicate that an assay designed to evaluate pediatric cancer-specific variants, including gene fusions, may improve the detection of target-agent pairs for precision oncology.
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http://dx.doi.org/10.1093/jncics/pky079DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6447067PMC
October 2018

Comprehensive B Cell Phenotyping Profile for Chronic Graft-versus-Host Disease Diagnosis.

Biol Blood Marrow Transplant 2019 03 14;25(3):451-458. Epub 2018 Nov 14.

Division of Pediatric Hematology/Oncology/Blood and Marrow Transplant, Department of Pediatrics, BC Children's Hospital, University of British Columbia, Vancouver, Canada; Michael Cuccione Childhood Cancer Research Program, BC Children's Hospital Research Institute, Vancouver, Canada. Electronic address:

Previous studies have reported single B cell-related chronic graft-versus-host disease diagnostic (cGVHD) biomarkers, such as B cell-activating factor (BAFF), CD21, and immature B cells, but research on the performance of biomarker combinations and the covariate effect of steroids is lacking. The primary objective of this study was to determine the most accurate combination of B cell populations using cell surface staining flow cytometry in an independent cohort of patients with cGVHD. Secondary objectives included assessing the effect of corticosteroid use at sample collection on the makeup and accuracy of the diagnostic panel and identifying the mechanism underlying low surface expression of BAFF receptor (BAFF-R) on B cells in cGVHD. Flow cytometry analysis was performed in an adult cohort of post-HCT patients with cGVHD onset (n = 44) and time-matched recipients without cGVHD (n = 63). We confirmed that the onset of cGVHD was associated with higher soluble BAFF (sBAFF) levels, elevated CD27CD10CD21 CD19 B cell and classical switched memory B cell counts, and reduced transitional and naïve B cell counts. The highest single B cell population area under the receiver operating characteristic (ROC) curve (AUC) was .72 for transitional type 1 CD21 B cells. We also showed a significant inverse relationship between sBAFF and surface BAFF-R expression caused by sBAFF modulation of BAFF-R. Steroid use at sample collection influenced the significance of the sBAFF:B cell ratio, naïve and marginal zone-like B cells. The optimal combination of B cell subsets most significantly associated with cGVHD onset with or without concurrent corticosteroid use resulted in ROC AUCs of .87 and .84, respectively. Transitional and CD21 B cells were the only populations present in both panels; however, analyzing only these populations resulted in ROC AUCs of .79 and .78, respectively. This suggests that the inclusion of other populations and use of different panels depending on steroid use is necessary to achieve better accuracy. sBAFF was not a component of either panel. These novel B cell profiles could be tested prospectively in patients post-HSCT and could lead to focused mechanistic studies.
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http://dx.doi.org/10.1016/j.bbmt.2018.11.007DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6445755PMC
March 2019

C-terminal truncation of IFN-γ inhibits proinflammatory macrophage responses and is deficient in autoimmune disease.

Nat Commun 2018 06 20;9(1):2416. Epub 2018 Jun 20.

Department of Oral Biological and Medical Sciences, Faculty of Dentistry, University of British Columbia, 4.401-2350 Health Sciences Mall, Vancouver, V6T 1Z3, BC, Canada.

Controlled macrophage differentiation and activation in the initiation and resolution of inflammation is crucial for averting progression to chronic inflammatory and autoimmune diseases. Here we show a negative feedback mechanism for proinflammatory IFN-γ activation of macrophages driven by macrophage-associated matrix metalloproteinase 12 (MMP12). Through C-terminal truncation of IFN-γ at 135Glu↓Leu136 the IFN-γ receptor-binding site was efficiently removed thereby reducing JAK-STAT1 signaling and IFN-γ activation of proinflammatory macrophages. In acute peritonitis this signature was absent in Mmp12 mice and recapitulated in Mmp12 mice treated with a MMP12-specific inhibitor. Similarly, loss-of-MMP12 increases IFN-γ-dependent proinflammatory markers and iNOS/MHC class II macrophage accumulation with worse lymphadenopathy, arthritic synovitis and lupus glomerulonephritis. In active human systemic lupus erythematosus, MMP12 levels were lower and IFN-γ higher compared to treated patients or healthy individuals. Hence, macrophage proteolytic truncation of IFN-γ attenuates classical activation of macrophages as a prelude for resolving inflammation.
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http://dx.doi.org/10.1038/s41467-018-04717-4DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6010466PMC
June 2018

Higher levels of free plasma mitochondrial DNA are associated with the onset of chronic GvHD.

Bone Marrow Transplant 2018 10 21;53(10):1263-1269. Epub 2018 Mar 21.

Michael Cuccione Childhood Cancer Research Program, Department of Pediatrics, BC Children's Hospital, University of British Columbia, Vancouver, BC, Canada.

Toll-like receptor-9 (TLR9) responsive B cells have previously been associated with the onset of extensive chronic graft-versus-host disease (cGvHD). We hypothesized that the onset of cGvHD associated with a higher level of plasma-free mitochondrial DNA (mtDNA), a putative TLR9 agonist. Plasma cell-free mtDNA levels were measured in 39 adult patients post-HSCT with and without cGvHD. mtDNA was isolated from plasma and quantified by Q-PCR amplification. We correlated B cell responsiveness to CpG-DNA, a prototypical TLR9 agonist, and previously identified cGVHD biomarkers with mtDNA levels. Free plasma mtDNA were elevated in patients post-HSCT without cGvHD compared to normal non-HSCT adults. There was a significantly higher level of free plasma mtDNA associated with the onset of cGvHD (3080 ± 1586 versus 1834 ± 1435 copies/μL; p = 0.02) compared to 6 months post-HSCT controls. Free mtDNA levels post-HSCT correlated with B cell responsiveness to CpG-DNA and known cGvHD biomarkers: CXCL10 (p = 0.003), ICAM-1 (p = 0.007), CXCL9 (p = 0.03), sCD25 (p = 0.05) and sBAFF (p = 0.05), and percentage of CD21 B cells. Plasma levels of free mtDNA are increased in cGvHD and may represent an endogenous inflammatory stimulus for TLR9 expressing B cells.
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http://dx.doi.org/10.1038/s41409-018-0156-yDOI Listing
October 2018

CD56 natural killer regulatory cells in filgrastim primed donor blood or marrow products regulate chronic graft--host disease: the Canadian Blood and Marrow Transplant Group randomized 0601 study results.

Haematologica 2017 11 21;102(11):1936-1946. Epub 2017 Sep 21.

Michael Cuccione Childhood Cancer research Program, BC Children's Hospital, Department of Pediatrics, University of British Columbia, Vancouver, BC, Canada

Randomized trials have conclusively shown higher rates of chronic graft--host disease with filgrastim-stimulated apheresis peripheral blood as a donor source than unstimulated bone marrow. The Canadian Blood and Marrow Transplant Group conducted a phase 3 study of adults who received either filgrastim-stimulated apheresis peripheral blood or filgrastim-stimulated bone marrow from human leukocyte antigen-identical sibling donors. Because all donors received the identical filgrastim dosing schedule, this study allowed for a controlled evaluation of the impact of stem cell source on development of chronic graft--host disease. One hundred and twenty-one evaluable filgrastim-stimulated apheresis peripheral blood and filgrastim-stimulated bone marrow patient donor products were immunologically characterized by flow cytometry and tested for their association with acute and chronic graft--host disease within 2 years of transplantation. The immune populations evaluated included, regulatory T cells, central memory and effector T cells, interferon γ positive producing T cells, invariate natural killer T cells, regulatory natural killer cells, dendritic cell populations, macrophages, and activated B cells and memory B cells. When both filgrastim-stimulated apheresis peripheral blood and filgrastim-stimulated bone marrow were grouped together, a higher chronic graft--host disease frequency was associated with lower proportions of CD56 natural killer regulatory cells and interferon γ-producing T helper cells in the donor product. Lower CD56 natural killer regulatory cells displayed differential impacts on the development of extensive chronic graft--host disease between filgrastim-stimulated apheresis peripheral blood and filgrastim-stimulated bone marrow. In summary, while controlling for the potential impact of filgrastim on marrow, our studies demonstrated that CD56 natural killer regulatory cells had a much stronger impact on filgrastim-stimulated apheresis peripheral blood than on filgrastim-stimulated bone marrow. This supports the conclusion that a lower proportion of CD56 natural killer regulatory cells results in the high rate of chronic graft--host disease seen in filgrastim-stimulated apheresis peripheral blood. .
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http://dx.doi.org/10.3324/haematol.2017.170928DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5664398PMC
November 2017

Y-box-binding protein 1 contributes to IL-7-mediated survival signaling in B-cell precursor acute lymphoblastic leukemia.

Oncol Lett 2017 Jan 28;13(1):497-505. Epub 2016 Nov 28.

Michael Cuccione Childhood Cancer Research Program, Child and Family Research Institute, Department of Pediatrics, University of British Columbia, Vancouver, BC V5Z 4H4, Canada.

Y-box-binding protein 1 (YB-1) is a regulatory protein that is associated with drug resistance and relapse in solid tumors. As YB-1 mediates some of its activity through growth factor receptor signaling dysregulation, the present study compared the expression of YB-1 and interleukin 7 (IL-7) receptor α (IL-7Rα) in pediatric B-cell precursor (BCP) acute lymphoblastic leukemia (ALL) and normal BCP cells. The expression levels of IL-7Rα and YB-1 were higher in relapsed vs. diagnostic samples of primary BCP ALL; however, co-expression was also observed in a minor BCP cell population in samples from healthy donors. Functional crosstalk between YB-1 and IL-7R was detected: Overexpression of YB-1 increased surface levels of IL-7R in B cells, and the stimulation of BCP ALL cell lines and primary samples by IL-7 activated YB-1 by phosphorylation at S102 in a phosphatidylinositol 3-kinase-independent and MEK1/2-dependent manner. Targeted knockdown of YB-1 reduced IL-7-mediated protection against rapamycin, and an inhibitor of MEK1/2 potentiated rapamycin-mediated killing in the presence of IL-7. These data establish a novel link between two well-characterized pro-survival factors in acute leukemia, and suggest that YB-1 inhibition may represent a novel therapeutic strategy for increasing sensitivity to chemotherapy in patients with refractory acute B-cell leukemia.
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http://dx.doi.org/10.3892/ol.2016.5437DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5244896PMC
January 2017

Successful umbilical cord blood hematopoietic stem cell transplantation in pediatric patients with MDS/AML associated with underlying GATA2 mutations: two case reports and review of literature.

Pediatr Transplant 2016 Nov 15;20(7):1004-1007. Epub 2016 Jul 15.

Division of Hematology/Oncology/BMT, Department of Pediatrics, BC Children's Hospital, University of British Columbia, Vancouver, BC, Canada.

Germline GATA2 mutations have been associated with a vast array of clinical manifestations, as well as hematological deficiencies and a propensity to AML or MDS. We present two cases of pediatric AML/MDS with underlying GATA2 mutations who underwent a successful umbilical cord hematopoietic stem cell transplantation using two different conditioning regimens. These cases illustrate the importance of recognizing the clinical features associated with GATA2 mutations and performing the appropriate molecular testing. Diagnosis of heritable gene mutations associated with familial AML/MDS has significant clinical implication for the patients and affected families.
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http://dx.doi.org/10.1111/petr.12764DOI Listing
November 2016

XLF deficiency results in reduced N-nucleotide addition during V(D)J recombination.

Blood 2016 08 8;128(5):650-9. Epub 2016 Jun 8.

Department of Immunology, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands;

Repair of DNA double-strand breaks (DSBs) by the nonhomologous end-joining pathway (NHEJ) is important not only for repair of spontaneous breaks but also for breaks induced in developing lymphocytes during V(D)J (variable [V], diversity [D], and joining [J] genes) recombination of their antigen receptor loci to create a diverse repertoire. Mutations in the NHEJ factor XLF result in extreme sensitivity for ionizing radiation, microcephaly, and growth retardation comparable to mutations in LIG4 and XRCC4, which together form the NHEJ ligation complex. However, the effect on the immune system is variable (mild to severe immunodeficiency) and less prominent than that seen in deficiencies of NHEJ factors ARTEMIS and DNA-dependent protein kinase catalytic subunit, with defects in the hairpin opening step, which is crucial and unique for V(D)J recombination. Therefore, we aimed to study the role of XLF during V(D)J recombination. We obtained clinical data from 9 XLF-deficient patients and performed immune phenotyping and antigen receptor repertoire analysis of immunoglobulin (Ig) and T-cell receptor (TR) rearrangements, using next-generation sequencing in 6 patients. The results were compared with XRCC4 and LIG4 deficiency. Both Ig and TR rearrangements showed a significant decrease in the number of nontemplated (N) nucleotides inserted by terminal deoxynucleotidyl transferase, which resulted in a decrease of 2 to 3 amino acids in the CDR3. Such a reduction in the number of N-nucleotides has a great effect on the junctional diversity, and thereby on the total diversity of the Ig and TR repertoire. This shows that XLF has an important role during V(D)J recombination in creating diversity of the repertoire by stimulating N-nucleotide insertion.
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http://dx.doi.org/10.1182/blood-2016-02-701029DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4974199PMC
August 2016

Exome Sequencing and the Management of Neurometabolic Disorders.

N Engl J Med 2016 Jun 25;374(23):2246-55. Epub 2016 May 25.

From the Centre for Molecular Medicine and Therapeutics (M.T.-G., C. Shyr, X.C.Y., L.-H.Z., J.J.Y.L., B.I.D., I.G., W.W.W., C.D.K.), the Departments of Medical Genetics (M.T.-G., C. Shyr, C.J.R., X.C.Y., J.J.Y.L., L.A., J.M.F., S.L., M.M., M.I.V.A., A.M.L., W.W.W.), Pediatrics (C.J.R., G.A.H., R.S., L.-H.Z., A.P.B., B.I.D., M.B.C., M.D., T.D., J.D., A. Michoulas, D.M., J.R., K.R.S., K.S., S.E.T., John Wu, S.S.-I., C.D.K.), and Pathology and Laboratory Medicine (B.R., P.E., H.V., G.S.), the Child and Family Research Institute (M.T.-G., C. Shyr, C.J.R., G.A.H., X.C.Y., A.P.B., J.J.Y.L., B.I.D., L.A., M.B.C., M.D., J.D., J.M.F., I.G., S.L., M.M., D.M., J.R., K.R.S., K.S., S.E.T., M.I.V.A., John Wu, P.E., A.M.L., H.V., S.S.-I., G.S., W.W.W., C.D.K.), and the Division of Endocrinology, Adult Metabolic Diseases Clinic (A. Mattman, S. Sirrs), University of British Columbia, and the Divisions of Biochemical Diseases (G.A.H., R.S., B.S., S.S.-I., C.D.K.), Pediatric Neurology (M.B.C., M.D., A. Michoulas, K.S.), Pediatric Nephrology (J.D.), Pediatric Endocrinology (D.M.), and Immunology (S.E.T.) and the Division of Hematology, Oncology and Transplantation, Michael Cuccione Childhood Cancer Research Program (J.R., K.R.S., John Wu), BC Children's Hospital, Vancouver, the Department of Pathology and Laboratory Medicine, Hospital for Sick Children, University of Toronto, Toronto (J.C.), the Department of Biological and Computing Sciences, University of Alberta (R.M., D.W.), and the National Institute for Nanotechnology (D.W.), Edmonton, AB, and the Department of Biomedical Physiology and Kinesiology, Simon Fraser University, Burnaby, BC (M. Abdelsayed, P.R.) - all in Canada; the Division of Genetics, Department of Pediatrics, King Saud Bin Abdulaziz University for Health Sciences, King Abdulaziz Medical City, Riyadh, Saudi Arabia (M. Alfadhel); the Division of Metabolism and Children's Research Center, University Children's Hospital Zurich, Zurich (M.R.B., P.B.), and the Departmen

Background: Whole-exome sequencing has transformed gene discovery and diagnosis in rare diseases. Translation into disease-modifying treatments is challenging, particularly for intellectual developmental disorder. However, the exception is inborn errors of metabolism, since many of these disorders are responsive to therapy that targets pathophysiological features at the molecular or cellular level.

Methods: To uncover the genetic basis of potentially treatable inborn errors of metabolism, we combined deep clinical phenotyping (the comprehensive characterization of the discrete components of a patient's clinical and biochemical phenotype) with whole-exome sequencing analysis through a semiautomated bioinformatics pipeline in consecutively enrolled patients with intellectual developmental disorder and unexplained metabolic phenotypes.

Results: We performed whole-exome sequencing on samples obtained from 47 probands. Of these patients, 6 were excluded, including 1 who withdrew from the study. The remaining 41 probands had been born to predominantly nonconsanguineous parents of European descent. In 37 probands, we identified variants in 2 genes newly implicated in disease, 9 candidate genes, 22 known genes with newly identified phenotypes, and 9 genes with expected phenotypes; in most of the genes, the variants were classified as either pathogenic or probably pathogenic. Complex phenotypes of patients in five families were explained by coexisting monogenic conditions. We obtained a diagnosis in 28 of 41 probands (68%) who were evaluated. A test of a targeted intervention was performed in 18 patients (44%).

Conclusions: Deep phenotyping and whole-exome sequencing in 41 probands with intellectual developmental disorder and unexplained metabolic abnormalities led to a diagnosis in 68%, the identification of 11 candidate genes newly implicated in neurometabolic disease, and a change in treatment beyond genetic counseling in 44%. (Funded by BC Children's Hospital Foundation and others.).
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http://dx.doi.org/10.1056/NEJMoa1515792DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4983272PMC
June 2016

NANS-mediated synthesis of sialic acid is required for brain and skeletal development.

Nat Genet 2016 07 23;48(7):777-84. Epub 2016 May 23.

Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia, Canada.

We identified biallelic mutations in NANS, the gene encoding the synthase for N-acetylneuraminic acid (NeuNAc; sialic acid), in nine individuals with infantile-onset severe developmental delay and skeletal dysplasia. Patient body fluids showed an elevation in N-acetyl-D-mannosamine levels, and patient-derived fibroblasts had reduced NANS activity and were unable to incorporate sialic acid precursors into sialylated glycoproteins. Knockdown of nansa in zebrafish embryos resulted in abnormal skeletal development, and exogenously added sialic acid partially rescued the skeletal phenotype. Thus, NANS-mediated synthesis of sialic acid is required for early brain development and skeletal growth. Normal sialylation of plasma proteins was observed in spite of NANS deficiency. Exploration of endogenous synthesis, nutritional absorption, and rescue pathways for sialic acid in different tissues and developmental phases is warranted to design therapeutic strategies to counteract NANS deficiency and to shed light on sialic acid metabolism and its implications for human nutrition.
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http://dx.doi.org/10.1038/ng.3578DOI Listing
July 2016

Successful clinical treatment and functional immunological normalization of human MALT1 deficiency following hematopoietic stem cell transplantation.

Clin Immunol 2016 07 22;168:1-5. Epub 2016 Apr 22.

Department of Pediatrics, BC Children's Hospital, Child & Family Research Institute, University of British Columbia, Vancouver, BC, Canada. Electronic address:

MALT1 mutations impair normal NF-κB activation and paracaspase activity to cause a novel combined immunodeficiency. The clinical and immunological phenotype of MALT1 deficiency can be successfully treated with hematopoietic stem cell transplantation following reduced intensity conditioning.
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http://dx.doi.org/10.1016/j.clim.2016.04.011DOI Listing
July 2016

Heterogeneity of chronic graft-versus-host disease biomarkers: association with CXCL10 and CXCR3+ NK cells.

Blood 2016 06 28;127(24):3082-91. Epub 2016 Mar 28.

Fred Hutchinson Cancer Research Center and the University of Washington, Seattle, WA;

Chronic graft-versus-host disease (cGVHD) remains one of the most significant long-term complications after allogeneic blood and marrow transplantation. Diagnostic biomarkers for cGVHD are needed for early diagnosis and may guide identification of prognostic markers. No cGVHD biomarker has yet been validated for use in clinical practice. We evaluated both previously known markers and performed discovery-based analysis for cGVHD biomarkers in a 2 independent test sets (total of 36 cases ≤1 month from diagnosis and 31 time-matched controls with no cGVHD). On the basis of these results, 11 markers were selected and evaluated in 2 independent replication cohorts (total of 134 cGVHD cases and 154 controls). cGVHD cases and controls were evaluated for several clinical covariates, and their impact on biomarkers was identified by univariate analysis. The 2 replications sets were relatively disparate in the biomarkers they replicated. Only sBAFF and, most consistently, CXCL10 were identified as significant in both replication sets. Other markers identified as significant in only 1 replication set included intercellular adhesion molecule 1 (ICAM-1), anti-LG3, aminopeptidase N, CXCL9, endothelin-1, and gelsolin. Multivariate analysis found that all covariates evaluated affected interpretation of the biomarkers. CXCL10 had an increased significance in combination with anti-LG3 and CXCL9, or inversely with CXCR3(+)CD56(bright) natural killer (NK) cells. There was significant heterogeneity of cGVHD biomarkers in a large comprehensive evaluation of cGVHD biomarkers impacted by several covariates. Only CXCL10 strongly correlated in both replication sets. Future analyses for plasma cGVHD biomarkers will need to be performed on very large patient groups with consideration of multiple covariates.
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http://dx.doi.org/10.1182/blood-2015-09-668251DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4911864PMC
June 2016

The genotypic and phenotypic spectrum of PIGA deficiency.

Orphanet J Rare Dis 2015 Feb 27;10:23. Epub 2015 Feb 27.

Centre for Molecular Medicine and Therapeutics, Vancouver, Canada.

Background: Phosphatidylinositol glycan biosynthesis class A protein (PIGA) is one of the enzymes involved in the biosynthesis of glycosylphosphatidylinositol (GPI) anchor proteins, which function as enzymes, adhesion molecules, complement regulators and co-receptors in signal transduction pathways. Until recently, only somatic PIGA mutations had been reported in patients with paroxysmal nocturnal hemoglobinuria (PNH), while germline mutations had not been observed, and were suspected to result in lethality. However, in just two years, whole exome sequencing (WES) analyses have identified germline PIGA mutations in male patients with XLIDD (X-linked intellectual developmental disorder) with a wide spectrum of clinical presentations.

Methods And Results: Here, we report on a new missense PIGA germline mutation [g.15342986C>T (p.S330N)] identified via WES followed by Sanger sequencing, in a Chinese male infant presenting with developmental arrest, infantile spasms, a pattern of lesion distribution on brain MRI resembling that typical of maple syrup urine disease, contractures, dysmorphism, elevated alkaline phosphatase, mixed hearing loss (a combination of conductive and sensorineural), liver dysfunction, mitochondrial complex I and V deficiency, and therapy-responsive dyslipidemia with confirmed lipoprotein lipase deficiency. X-inactivation studies showed skewing in the clinically unaffected carrier mother, and CD109 surface expression in patient fibroblasts was 57% of that measured in controls; together these data support pathogenicity of this mutation. Furthermore, we review all reported germline PIGA mutations (1 nonsense, 1 frameshift, 1 in-frame deletion, five missense) in 8 unrelated families.

Conclusions: Our case further delineates the heterogeneous phenotype of this condition for which we propose the term 'PIGA deficiency'. While the phenotypic spectrum is wide, it could be classified into two types (severe and less severe) with shared hallmarks of infantile spasms with hypsarrhythmia on EEG and profound XLIDD. In severe PIGA deficiency, as described in our patient, patients also present with dysmorphic facial features, multiple CNS abnormalities, such as thin corpus callosum and delayed myelination, as well as hypotonia and elevated alkaline phosphatase along with liver, renal, and cardiac involvement; its course is often fatal. The less severe form of PIGA deficiency does not involve facial dysmorphism and multiple CNS abnormalities; instead, patients present with milder IDD, treatable seizures and generally a longer lifespan.
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http://dx.doi.org/10.1186/s13023-015-0243-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4348372PMC
February 2015

The CARD11-BCL10-MALT1 (CBM) signalosome complex: Stepping into the limelight of human primary immunodeficiency.

J Allergy Clin Immunol 2014 Aug;134(2):276-84

Centre for Chronic Immunodeficiency (CCI), University Medical Center Freiburg and University of Freiburg, Freiburg, Germany.

Next-generation DNA sequencing has accelerated the genetic characterization of many human primary immunodeficiency diseases (PIDs). These discoveries can be lifesaving for the affected patients and also provide a unique opportunity to study the effect of specific genes on human immune function. In the past 18 months, a number of independent groups have begun to define novel PIDs caused by defects in the caspase recruitment domain family, member 11 (CARD11)-B-cell chronic lymphocytic leukemia/lymphoma 10 (BCL10)-mucosa-associated lymphoid tissue lymphoma translocation gene 1 (MALT1 [CBM]) signalosome complex. The CBM complex forms an essential molecular link between the triggering of cell-surface antigen receptors and nuclear factor κB activation. Germline mutations affecting the CBM complex are now recognized as the cause of novel combined immunodeficiency phenotypes, which all share abnormal nuclear factor κB activation and dysregulated B-cell development as defining features. For this "Current perspectives" article, we have engaged experts in both basic biology and clinical immunology to capture the worldwide experience in recognizing and managing patients with PIDs caused by CBM complex mutations.
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http://dx.doi.org/10.1016/j.jaci.2014.06.015DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4167767PMC
August 2014

Combined immunodeficiency associated with homozygous MALT1 mutations.

J Allergy Clin Immunol 2014 May 12;133(5):1458-62, 1462.e1-7. Epub 2013 Dec 12.

Department of Pediatrics, Child & Family Research Institute, University of British Columbia, Vancouver, British Columbia, Canada. Electronic address:

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http://dx.doi.org/10.1016/j.jaci.2013.10.045DOI Listing
May 2014

Severe combined immunodeficiency (SCID) in Canadian children: a national surveillance study.

J Clin Immunol 2013 Nov;33(8):1310-6

Purpose: Severe Combined Immune Deficiency (SCID) is universally fatal unless treated with hematopoietic stem cell transplantation (HSCT). Following the identification of disseminated Bacille Calmette-Guérin (BCG) infections in Canadian First Nations, Métis and Inuit (FNMI) children with unrecognized primary immune deficiencies, a national surveillance study was initiated in order to determine the incidence, diagnosis, treatment and outcome of children with SCID in Canada.

Methods: Canadian pediatricians were asked to complete a monthly reporting form if they had seen a suspected SCID case, from 2004 to 2010, through the Canadian Paediatric Surveillance Program (CPSP). If the case met CPSP SCID criteria, more detailed data, including demographics and clinical information about investigations, treatment and outcome was collected.

Results: A total of 40 cases of SCID were confirmed for an estimated incidence of SCID in non-FNMI Canadian children of 1.4 per 100,000 live births (95 % CI 1 to 1.9/100,000). The proportion of SCID cases that were FNMI (17.5 %) was almost three times higher than was expected on the basis of proportion of the pediatric population estimated to be FNMI (6.3 %) resulting in an estimated incidence of 4.4 per 100,000 live births (95 % CI 2.1 to 9.2/100,000) in FNMI Canadian children. The mean age at diagnosis for all SCID cases was 4.2 months (range 1–583 days). There were 12 deaths (30 %; 95 % CI 18–46 %); seven died of confirmed or suspected infections before they could receive an HSCT.

Conclusions: The frequency of SCID cases in FNMI children is higher than in the general Canadian pediatric population. The high mortality rate, due primarily to infection, suggests that early diagnosis by newborn screening followed by HSCT could significantly benefit children with SCID.
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http://dx.doi.org/10.1007/s10875-013-9952-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7102302PMC
November 2013

Multiple persistent ganglioneuromas likely arising from the spontaneous maturation of metastatic neuroblastoma.

J Pediatr Hematol Oncol 2012 Mar;34(2):151-3

Division of Hematology/Oncology/BMT, Department of Pediatrics, Faculty of Medicine, University of British Columbia/BC Children's Hospital, Vancouver, British Columbia, Canada.

A 10-year-old girl with multiple persistent ganglioneuromas originating from the spontaneous maturation of a metastatic neuroblastoma is described. Multiple biopsies confirm progressive maturation and urine catecholamines, which were initially elevated, have normalized over time. The management and risk of malignant transformation of ganglioneuromas is discussed.
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http://dx.doi.org/10.1097/MPH.0b013e318221ca82DOI Listing
March 2012

Early and late extensive chronic graft-versus-host disease in children is characterized by different Th1/Th2 cytokine profiles: findings of the Children's Oncology Group Study ASCT0031.

Biol Blood Marrow Transplant 2011 Dec 25;17(12):1804-13. Epub 2011 May 25.

Children's Oncology Group, Pediatric Hematology/Oncology/Bone Marrow Transplantation, British Columbia Children's Hospital/University of British Columbia, Vancouver, British Columbia, Canada.

Numerous mechanisms underlie chronic graft-versus-host disease (cGVHD), including skewing of Th1/Th2 cytokine expression. There are biological differences between early-onset and late-onset cGVHD. To test whether different Th1/Th2 cytokines are associated with early- or late-onset cGVHD, peripheral blood was collected from 63 children enrolled on the Children's Oncology Group Phase III trial ASCT0031 evaluating hydroxychloroquine therapy for newly diagnosed extensive cGVHD. mRNA expression of interferon (IFN)-γ and interleukin (IL)-2, -4, and -10 from stimulated peripheral blood mononuclear cells was evaluated by quantitative polymerase chain reaction. Early-onset cGVHD (n = 33) was characterized by decreased expression of IFN-γ and IL-2 mRNA after nonspecific phorbol 12-myristate 13-acetate-ionomycin stimulation. In contrast, late-onset cGVHD (n = 11) was characterized by decreased expression of IL-4 and IL-2 mRNA after anti-CD3 stimulation of T cells. Receiver-operating characteristic curve analysis revealed that IFN-γ expression was correlated with the absence of early cGVHD (area under the curve [AUC] = 0.77) and that IL-4 (AUC = 0.89) and IL-2 (AUC = 0.84) expression was correlated with the absence of late cGVHD. There was no correlation between cytokine expression and a specific immune cell subset. Increased expression of Foxp3 mRNA was seen in early-onset cGVHD and late controls. The different time-dependent cytokine profiles in patients with newly diagnosed cGVHD suggests that the mechanisms underlying cGVHD are temporally regulated. Although larger validation studies are needed, our data suggest that cytokine profiles have a potential use as biomarkers for the diagnosis of cGVHD.
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http://dx.doi.org/10.1016/j.bbmt.2011.05.011DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3190042PMC
December 2011

Biomarkers in chronic graft-versus-host disease.

Expert Rev Hematol 2011 Jun;4(3):329-42

Division of Oncology, Hematology and BMT, Department of Pediatrics, BC Children's Hospital/University of British Columbia, Vancouver, BC, Canada.

Chronic graft-versus-host disease (cGVHD ) is a leading cause of allogeneic hematopoietic stem-cell transplantation-related mortality and morbidity. It is an immune-mediated disorder that can target almost any organ in the body, often with devastating consequences. The immune-suppressive medications currently used to treat it are equally toxic and are often not very effective. At this time, our understanding of its pathophysiology is limited. The discovery of potential biomarkers offers new possibilities in the clinical management of cGVHD. They could potentially be used for diagnosing cGVHD, for predicting or evaluating response to therapy and for unique insights into the pathophysiology underlying the clinical manifestations of cGVHD. Understanding the biological origins of these biomarkers can help us construct a more comprehensive and clinically relevant model for the pathogenesis of this disease. In this article, we review existing evidence for candidate biomarkers that have been identified in the framework of how they may contribute to the pathophysiology of cGVHD. Issues regarding the discovery and application of biomarkers are discussed.
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http://dx.doi.org/10.1586/ehm.11.27DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3132532PMC
June 2011

Somatic activation of oncogenic Kras in hematopoietic cells initiates a rapidly fatal myeloproliferative disorder.

Proc Natl Acad Sci U S A 2004 Jan 29;101(2):597-602. Epub 2003 Dec 29.

Department of Pediatrics, University of California, San Francisco, CA 94143, USA.

RAS mutations are common in myeloid malignancies; however, it is not known whether oncogenic RAS can initiate leukemia. We show that expressing mutant K-Ras(G12D) protein from the endogenous murine locus rapidly induces a fatal myeloproliferative disorder with 100% penetrance characterized by tissue infiltration, hypersensitivity to growth factors, and hyperproliferation. Hematopoietic cells from diseased mice demonstrated increased levels of Ras-GTP, but effector kinases were not constitutively phosphorylated and responded normally to growth factors. Oncogenic RAS is sufficient to initiate myeloid leukemogenesis in mice, and this provides an in vivo system for biologic and preclinical studies.
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http://dx.doi.org/10.1073/pnas.0307203101DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC327193PMC
January 2004