Elizabeth Garabedian

Actionable Diagnosis of Neuroleptospirosis by Next-Generation Sequencing

A 14-year-old boy with severe combined immunodeficiency presented three times to a medical facility over a period of 4 months with fever and headache that progressed to hydrocephalus and status epilepticus necessitating a medically induced coma. Diagnostic workup including brain biopsy was unrevealing. Unbiased next-generation sequencing of the cerebrospinal fluid identified 475 of 3,063,784 sequence reads (0.016%) corresponding to leptospira infection. Clinical assays for leptospirosis were negative. Targeted antimicrobial agents were administered, and the patient was discharged home 32 days later with a status close to his premorbid condition. Polymerase-chain-reaction (PCR) and serologic testing at the Centers for Disease Control and Prevention (CDC) subsequently confirmed evidence of Leptospira santarosai infection.

Somatic mosaicism in Wiskott–Aldrich syndrome suggests in vivo reversion by a DNA slippage mechanism

Somatic mosaicism caused by in vivo reversion of inherited mutations has been described in several human genetic disorders. Back mutations resulting in restoration of wild-type sequences and second-site mutations leading to compensatory changes have been shown in mosaic individuals. In most cases, however, the precise genetic mechanisms underlying the reversion events have remained unclear, except for the few instances where crossing over or gene conversion have been demonstrated. Here, we report a patient affected with Wiskott–Aldrich syndrome (WAS) caused by a 6-bp insertion (ACGAGG) in the WAS protein gene, which abrogates protein expression. Somatic mosaicism was documented in this patient whose majority of T lymphocytes expressed nearly normal levels of WAS protein. These lymphocytes were found to lack the deleterious mutation and showed a selective growth advantage in vivo. Analysis of the sequence surrounding the mutation site showed that the 6-bp insertion followed a tandem repeat of the same six nucleotides. These findings strongly suggest that DNA polymerase slippage was the cause of the original germ-line insertion mutation in this family and that the same mechanism was responsible for its deletion in one of the propositus T cell progenitors, thus leading to reversion mosaicism.

Second-site mutation in the Wiskott-Aldrich syndrome (WAS) protein gene causes somatic mosaicism in two WAS siblings

Revertant mosaicism due to true back mutations or second-site mutations has been identified in several inherited disorders. The occurrence of revertants is considered rare, and the underlying genetic mechanisms remain mostly unknown. Here we describe somatic mosaicism in two brothers affected with Wiskott-Aldrich syndrome (WAS). The original mutation causing disease in this family is a single base insertion (1305insG) in the WAS protein (WASP) gene, which results in frameshift and abrogates protein expression. Both patients, however, showed expression of WASP in a fraction of their T cells that were demonstrated to carry a second-site mutation causing the deletion of 19 nucleotides from nucleotide 1299 to 1316. This deletion abrogated the effects of the original mutation and restored the WASP reading frame. In vitro expression studies indicated that mutant protein encoded by the second-site mutation was expressed and functional, since it was able to bind to cellular partners and mediate T cell receptor/CD3 downregulation. These observations were consistent with evidence of in vivo selective advantage of WASP-expressing lymphocytes. Molecular analysis revealed that the sequence surrounding the deletion contained two 4-bp direct repeats and that a hairpin structure could be formed by five GC pairs within the deleted fragment. These findings strongly suggest that slipped mispairing was the cause of this second-site mutation and that selective accumulation of WASP-expressing T lymphocytes led to revertant mosaicism in these patients.

Multicentric dermatofibrosarcoma protuberans in patients with adenosine deaminase-deficient severe combined immune deficiency

BACKGROUND Dermatofibrosarcoma protuberans (DFSP) is a rare malignant skin tumor associated with a characteristic chromosomal translocation (t[17;22][q22;q13]) resulting in the COL1A1-platelet-derived growth factor β(PDGFB) fusion gene. This malignancy is rarely diagnosed in childhood. OBJECTIVE We observed an unexpected high incidence of this DFSP in children affected with adenosine deaminase-deficient severe combined immunodeficiency (ADA-SCID) and set out to evaluate the association of these 2 clinical entities. METHODS Twelve patients with ADA-SCID were evaluated with a complete dermatologic examination and skin biopsy when indicated. Conventional cytogenetic and molecular analyses (fluorescence in situ hybridization, RT-PCR, or both) were performed when possible. RESULTS Eight patients were found to have DFSP. Six patients had multicentric involvement (4-15 lesions), primarily of the trunk and extremities. Most lesions presented as 2- to 15-mm, round atrophic plaques. Nodular lesions were present in 3 patients. In all cases CD34 expression was diffusely positive, and diagnosis was confirmed either by means of cytogenetic analysis, molecular testing, or both. The characteristic DFSP-associated translocation, t(17;22)(q22;q13), was identified in 6 patients; results of fluorescence in situ hybridization were positive for fusion of the COL1A1 and PDGFB loci in 7 patients; and RT-PCR showed the COL1A1-PDGFB fusion transcript in 6 patients. CONCLUSIONS We describe a previously unrecognized association between ADA-SCID and DFSP with unique features, such as multicentricity and occurrence in early age. We hypothesize that the t(17;22)(q22;q13) translocation that results in dermal overexpression of PDGFB and favors the development of fibrotic tumors might arise because of the known DNA repair defect in patients with ADA-SCID. Although the natural course of DFSP in the setting of ADA-SCID is unknown, this observation should prompt regular screening for DFSP in patients with ADA-SCID.

Myeloid dysplasia and bone marrow hypocellularity in adenosine deaminase-deficient severe combined immune deficiency

Genetic deficiency of adenosine deaminase (ADA) can cause profound lymphopenia and result in the clinical presentation of severe combined immune deficiency (SCID). However, because of the ubiquitous expression of ADA, ADA-deficient patients often present also with nonimmunologic clinical problems, affecting the skeletal, central nervous, endocrine, and gastrointestinal systems. We now report that myeloid dysplasia features and bone marrow hypocellularity are often found in patients with ADA-SCID. As a clinical correlate to this finding, we have observed vulnerability to antibiotic-induced myelotoxicity and prolonged neutropenia after nonmyeloablative chemotherapy. We have also noted that, in the absence of enzyme replacement therapy, absolute neutrophil counts of patients with ADA deficiency vary inversely with the accumulation of deoxynucleotides. These data have significant implications for the application of standard and investigational therapies to patients with ADA-SCID and support further studies to investigate the possibility that ADA deficiency is associated with a stem cell defect. These trials were registered at www.clinicaltrials.gov as #NCT00018018 and #NCT00006319.

FOXP3+ Tregs require WASP to restrain Th2-mediated food allergy

In addition to the infectious consequences of immunodeficiency, patients with Wiskott-Aldrich syndrome (WAS) often suffer from poorly understood exaggerated immune responses that result in autoimmunity and elevated levels of serum IgE. Here, we have shown that WAS patients and mice deficient in WAS protein (WASP) frequently develop IgE-mediated reactions to common food allergens. WASP-deficient animals displayed an adjuvant-free IgE-sensitization to chow antigens that was most pronounced for wheat and soy and occurred under specific pathogen-free as well as germ-free housing conditions. Conditional deletion of Was in FOXP3+ Tregs resulted in more severe Th2-type intestinal inflammation than that observed in mice with global WASP deficiency, indicating that allergic responses to food allergens are dependent upon loss of WASP expression in this immune compartment. While WASP-deficient Tregs efficiently contained Th1- and Th17-type effector differentiation in vivo, they failed to restrain Th2 effector responses that drive allergic intestinal inflammation. Loss of WASP was phenotypically associated with increased GATA3 expression in effector memory FOXP3+ Tregs, but not in naive-like FOXP3+ Tregs, an effect that occurred independently of increased IL-4 signaling. Our results reveal a Treg-specific role for WASP that is required for prevention of Th2 effector cell differentiation and allergic sensitization to dietary antigens.

Molecular and phenotypic abnormalities of B lymphocytes in patients with Wiskott-Aldrich syndrome

produced much lower IFN-g toward both fungi (Fig 1, E). Production of other cytokines (IL-1b, IL-6, TNF-a, and MIP1a) was studied in patient 1 and was found to be comparable with that in normal controls (see Fig E3 in this article’s Online Repository at www.jacionline.org). Previous studies demonstrated that patients with CMC caused by gain-of-phosphorylation STAT1 mutations had impaired TH1 and TH17 response as a result of defective signaling through the IL-12 and IL-23 pathways. Majority of these gainof-phosphorylation mutants are located in the coiledcoil domain and 2 in the DNA-binding domain. Impaired dephosphorylation of STAT1 enhances gamma-interferon activation factor–dependent cellular response to IFN-a/b, IFN-g, and IL-27, which are repressors of TH17 development from naive T cells. The enhanced response mediated by STAT1 probably impairs TH17 immunity. 5

Clinical efficacy of gene-modified stem cells in adenosine deaminase–deficient immunodeficiency

BACKGROUND. Autologous hematopoietic stem cell transplantation (HSCT) of gene-modified cells is an alternative to enzyme replacement therapy (ERT) and allogeneic HSCT that has shown clinical benefit for adenosine deaminase–deficient (ADA-deficient) SCID when combined with reduced intensity conditioning (RIC) and ERT cessation. Clinical safety and therapeutic efficacy were evaluated in a phase II study. METHODS. Ten subjects with confirmed ADA-deficient SCID and no available matched sibling or family donor were enrolled between 2009 and 2012 and received transplantation with autologous hematopoietic CD34+ cells that were modified with the human ADA cDNA (MND-ADA) &ggr;-retroviral vector after conditioning with busulfan (90 mg/m2) and ERT cessation. Subjects were followed from 33 to 84 months at the time of data analysis. Safety of the procedure was assessed by recording the number of adverse events. Efficacy was assessed by measuring engraftment of gene-modified hematopoietic stem/progenitor cells, ADA gene expression, and immune reconstitution. RESULTS. With the exception of the oldest subject (15 years old at enrollment), all subjects remained off ERT with normalized peripheral blood mononuclear cell (PBMC) ADA activity, improved lymphocyte numbers, and normal proliferative responses to mitogens. Three of nine subjects were able to discontinue intravenous immunoglobulin replacement therapy. The MND-ADA vector was persistently detected in PBMCs (vector copy number [VCN] = 0.1–2.6) and granulocytes (VCN = 0.01–0.3) through the most recent visits at the time of this writing. No patient has developed a leukoproliferative disorder or other vector-related clinical complication since transplant. CONCLUSION. These results demonstrate clinical therapeutic efficacy from gene therapy for ADA-deficient SCID, with an excellent clinical safety profile. TRIAL REGISTRATION. ClinicalTrials.gov NCT00794508. FUNDING. Food and Drug Administration Office of Orphan Product Development award, RO1 FD003005; NHLBI awards, PO1 HL73104 and Z01 HG000122; UCLA Clinical and Translational Science Institute awards, UL1RR033176 and UL1TR000124.

Elevated IgE and atopy in patients treated for early onset ADA-SCID

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Cancer in primary immunodeficiency diseases: Cancer incidence in the United States Immune Deficiency Network Registry

Background: We evaluated the overall and site‐specific incidence of cancer in subjects with primary immunodeficiency diseases (PIDD) enrolled in the United States Immune Deficiency Network (USIDNET) registry compared with age‐adjusted cancer incidence in the Surveillance, Epidemiology and End Results Program (SEER) database. Objective: We hypothesized that subjects with PIDD would have an increased incidence of cancer due to impaired immune function. Methods: Overall and site‐specific cancer incidence rates were evaluated in subjects with PIDD (n = 3658) enrolled in the USIDNET registry from 2003 to 2015 and compared with age‐adjusted incidence rates in the SEER database. Results: We observed a 1.42‐fold excess relative risk of cancer in subjects with PIDD compared with the age‐adjusted SEER population (P < .001). Men with PIDD had a 1.91‐fold excess relative risk of cancer compared with the age‐adjusted male population (P < .001), while women with PIDD had similar overall cancer rates compared with the age‐adjusted female population. Of the 4 most common malignancies in men and women in SEER (lung, colon, breast, and prostate cancers), we found no significant increase in these diagnoses in subjects with PIDD. Significant increases in lymphoma in both men (10‐fold increase, P < .001) and women (8.34‐fold increase, P < .001) with PIDD were observed. Conclusions: Excess incidence of cancer occurred in subjects with PIDD. An excess of lymphoma in specific PIDD populations principally drove this increased incidence, while no increased risk of the most common solid tumor malignancies was observed. These data point to a restricted role of the immune system in protecting from specific cancers.