Two siblings presenting with novel ADA2 variants, lymphoproliferation, persistence of large granular lymphocytes, and T-cell perturbations.

The presence of large granular lymphocytes has been reported in patients with ADA2 deficiency and T-LGL leukemia. Here we describe two siblings with novel ADA2 variants, expanding the mutational spectrum of ADA2 deficiency. We show that lymphoproliferation, persistence of large granular lymphocytes, T-cell perturbations, and activation of PI3K pathway, measured by means of phosphorylation levels of S6, are detectable in DADA2 patients without T-LGL leukemia.

Generation of induced Pluripotent Stem Cells (UNIBSi008-A, UNIBSi008-B, UNIBSi008-C) from an Ataxia-Telangiectasia (AT) patient carrying a novel homozygous deletion in ATM gene.

Using a Sendai Virus based vector delivering Yamanaka Factors, we generated induced Pluripotent Stem Cells (iPSCs) from peripheral blood mononuclear cells of a patient affected by Ataxia Telangiectasia (AT), caused by a novel homozygous deletion in ATM, spanning exons 5-7. Three clones were fully characterized for pluripotency and capability to differentiate. These clones preserved the causative mutation of parental cells and genomic stability over time (>100 passages). Furthermore, in AT derived iPSCs we confirmed the impaired DNA damage response after ionizing radiation. All these data underline potential usefulness of our clones as in vitro AT disease model.

Early diagnosis of PI3Kδ syndrome in a 2 years old girl with recurrent otitis and enlarged spleen.

Heterozygous gain of function mutations in the gene encoding p110δ subunit of PI3K have been recently associated with activated PI3K-δ syndrome (APDS), a novel combined immune deficiency characterized by recurrent sinopulmonary infections, lymphopenia, reduced class-switched memory B cells, lymphadenopathy, CMV and/or EBV viremia and EBV-related lymphoma. Here we report a dominant gain of function PIK3CD mutation (E1021K) in a patient presenting with recurrent otitis media, massive splenomegaly, and persistent EBV-viraemia. The immunological studies showed low IgA level, but normal IgM, IgG, and normal antibody response to diphtheria and tetanus toxoid vaccination. Analysis of B lymphocyte subsets revealed abnormal expansion of transitional B cells, and low percentage of switched CD27+IgD- and CD27+IgD+ memory B cells. Analysis of T cell compartment unveiled prevalence of terminally differentiated cells. This study suggests that PIK3CD gain of function mutations should be suspected despite incomplete phenotype in patients with early onset splenomegaly, persistent EBV viremia and abnormal B and T cell subsets despite normal IgG levels. Currently the optimal treatment is still debated, but prompt management can hopefully diminish incidence of severe long-lasting sequelae (i.e. bronchiectasis, ear and sinus damage).

Dysregulation of the immune system in Aicardi-Goutières syndrome: another example in a TREX1-mutated patient.

Aicardi-Goutières syndrome (AGS) is a rare genetic encephalopathy characterized by neurological and extraneurological involvement. A clinical overlap between AGS and systemic lupus erythematosus (SLE) has been reported. We describe an AGS patient who developed autoimmune manifestations: thyroiditis, cANCA positivity, antiphospholipid antibodies and cerebral ischemia. This first description of antiphospholipid syndrome in a TREX1-mutated patient further expands the clinical spectrum of AGS. Although the clinical overlap with SLE may indicate common pathogenic mechanisms, the autoimmune manifestations in AGS are so extensive that we suggest they should be considered a clinical feature of the disease, rather than a sign of coexistent SLE.

Stem cell transplantation for the Wiskott-Aldrich syndrome: a single-center experience confirms efficacy of matched unrelated donor transplantation.

The treatment of Wiskott-Aldrich syndrome (WAS), a once uniformly fatal disorder, has evolved considerably as the use of hematopoietic stem cell transplant has become more widespread. For the majority of patients who lack an human leukocyte antigen-identical sibling, closely matched unrelated donor bone marrow transplant (MUD BMT) at an early age is an excellent option that nevertheless is not uniformly chosen. We retrospectively analyzed our experience with transplantation in 23 patients with WAS from 1990 to 2005 at the University of Brescia, Italy, of whom 16 received MUD BMT. Myeloablative chemotherapy was well tolerated with median neutrophil engraftment at day 18, and no cases of grade III or IV graft-vs-host disease. Overall survival was very good with 78.2% (18/23) of the whole cohort and 81.2% (13/16) of MUD BMT recipients surviving. Among 18 survivors, full donor engraftment was detected in 12 patients, and stable mixed chimerism in all blood lineages in four patients. Deaths were limited to patients who had received mismatched related BMT or who had severe clinical symptomatology at the time of transplantation, further emphasizing the safety and efficacy of MUD BMT when performed early in the clinical course of WAS.

X-chromosome inactivation analysis in a female carrier of FOXP3 mutation.

Immune dysregulation, polyendocrinopathy and enteropathy with X-linked inheritance (IPEX) is a serious disease arising from mutations in FOXP3. This gene codifies for a transcription factor whose dysfunction results in hyperactivation of T cells. It is not clear, however, why an intermediate phenotype is not seen in heterozygous females, who are completely healthy. In order to address this question, we investigated X-chromosome inactivation in peripheral blood lymphocytes from a heterozygous female with a child affected by IPEX. No preferential inactivation was shown in freshly sorted CD4+, CD8+, CD19+ cells or in IL-2 cultured CD4 and CD8 T cells, indicating that peripheral blood lymphocytes in these women are randomly selected. Moreover, only one single FOXP3 transcript was expressed by CD4 T cell clones analysed by RT-PCR, confirming that this gene is subject to X- inactivation. We hypothesize that hyper-activation of T cell in carriers of FOXP3 mutations is regulated by the presence of normal regulatory T cells.

SEN virus infection and its relationship to transfusion-associated hepatitis.

SEN virus (SEN-V) is a recently identified single-stranded, circular DNA virus. Two SEN-V variants (SENV-D and SENV-H) were assayed by polymerase chain reaction (PCR) to investigate their role in the causation of transfusion-associated non-A to E hepatitis. The incidence of SEN-V infection after transfusion was 30% (86 of 286) compared with 3% (3 of 97) among nontransfused controls (P < .001). Transfusion risk increased with the number of units transfused (P < .0001) and donor-recipient linkage for SEN-V was shown by sequence homology. The prevalence of SEN-V in 436 volunteer donors was 1.8%. Among patients with transfusion-associated non-A to E hepatitis, 11 of 12 (92%) were infected with SEN-V at the time of transfusion compared with 55 of 225 (24%) identically followed recipients who did not develop hepatitis (P < .001). No effect of SEN-V on the severity or persistence of coexistent hepatitis C virus (HCV) infection was observed. In 31 infected recipients, SEN-V persisted for greater than 1 year in 45% and for up to 12 years in 13%. SEN-V-specific RNA (a possible replicative intermediate) was recovered from liver tissue. In summary, SENV-D and -H were present in nearly 2% of US donors, and were unequivocally transmitted by transfusion and frequently persisted. The strong association of SEN-V with transfusion-associated non-A to E hepatitis compared with controls raises the possibility, but does not establish that SEN-V might be a causative agent of posttransfusion hepatitis. The vast majority of SEN-V-infected recipients did not develop hepatitis.

Presenilin 1 protein directly interacts with Bcl-2.

Presenilin proteins are involved in familial Alzheimer's disease, a neurodegenerative disorder characterized by massive death of neurons. We describe a direct interaction between presenilin 1 (PS1) and Bcl-2, a key factor in the regulation of apoptosis, by yeast two-hybrid interaction system, by co-immunoprecipitation, and by cross-linking experiments. Our data show that PS1 and Bcl-2 assemble into a macromolecular complex, and that they are released from this complex in response to an apoptotic stimulus induced by staurosporine. The results support the idea of cross-talk between these two proteins during apoptosis.