Hypomorphic RAG deficiency: impact of disease burden on survival and thymic recovery argues for early diagnosis and HSCT

Patients with hypomorphic mutations in the RAG1 or RAG2 gene present with either Omenn syndrome or atypical combined immunodeficiency with a wide phenotypic range. Hematopoietic stem cell transplantation (HSCT) is potentially curative, but data are scarce. We report on a worldwide cohort of 60 patients with hypomorphic RAG variants who underwent HSCT, 78% of whom experienced infections (29% active at HSCT), 72% had autoimmunity, and 18% had granulomas pretransplant. These complications are frequently associated with organ damage. Eight individuals (13%) were diagnosed by newborn screening or family history. HSCT was performed at a median of 3.4 years (range 0.3-42.9 years) from matched unrelated donors, matched sibling or matched family donors, or mismatched donors in 48%, 22%, and 30% of the patients, respectively. Grafts were T-cell depleted in 15 cases (25%). Overall survival at 1 and 4 years was 77.5% and 67.5% (median follow-up of 39 months). Infection was the main cause of death. In univariable analysis, active infection, organ damage pre-HSCT, T-cell depletion of the graft, and transplant from a mismatched family donor were predictive of worse outcome, whereas organ damage and T-cell depletion remained significant in multivariable analysis (hazard ratio [HR] = 6.01, HR = 8.46, respectively). All patients diagnosed by newborn screening or family history survived. Cumulative incidences of acute and chronic graft-versus-host disease were 35% and 22%, respectively. Cumulative incidences of new-onset autoimmunity was 15%. Immune reconstitution, particularly recovery of naïve CD4+ T cells, was faster and more robust in patients transplanted before 3.5 years of age, and without organ damage. These findings support the indication for early transplantation.

High rates of antiretroviral coverage and virological suppression in HIV-1-infected children and adolescents

OBJECTIVES

To assess the outcome of HIV-infected individuals attending one of the largest French pediatric HIV centers in 2016-2017 and to compare the rates of antiretroviral coverage and virological suppression with the UNAIDS targets.

PATIENTS AND METHODS

The clinical and immuno-virological status of 163 HIV-1-infected children and adolescents attending Necker Hospital in Paris, France, were investigated. Virological suppression was defined as an HIV-1 viral load<50 copies/mL for at least six months. All genotypic resistance tests performed since birth were analyzed.

RESULTS

Most patients were born in Sub-Saharan African countries (41.7%) or in France (38.0%). Their median age was 14 years [IQR 7.3-17.0]. Although 33.7% of individuals had a history of AIDS-defining clinical event(s), 86.5% of children/adolescents were free from HIV-related symptoms at their most recent evaluation. Antiretroviral coverage was high (98.2%; mainly including one integrase inhibitor [42.3%] or one protease inhibitor [23.9%]). At the last visit, most patients (82.8%) had normal CD4T lymphocytes counts (≥25%). Although 61.7% of antiretroviral-experienced children had resistance to≥1 drug class and 9.2% had triple-class resistance, 80.3% of patients receiving antiretrovirals for≥6 months (126/157) were virologically suppressed. International adoptees were more frequently virologically suppressed than other patients (96.0% versus 74.6%, P=0.02).

CONCLUSIONS

Antiretroviral coverage exceeded the second UNAIDS 90 target aimed at ending the AIDS epidemic. The rate of virological suppression, one of the highest reported in children in high-income countries, is approaching the third UNAIDS 90 target and the rate observed in French HIV-infected adults on antiretrovirals.

Cutaneous granulomas with primary immunodeficiency in children: a report of 17 new patients and a review of the literature

BACKGROUND

Paediatric cutaneous granuloma with primary immunodeficiency (PID) is a rare condition. The physiopathology is unclear, and treatment is challenging. We report on 17 paediatric cases and review the literature.

OBJECTIVES

To make dermatologists and dermatopathologists aware of the diagnostic value of skin granulomas in paediatric PID.

METHODS

We collected data on 17 patients with cutaneous granulomas and PID registered with us and also reviewed 33 cases from the literature.

RESULTS

Cutaneous granuloma was the presenting feature of the PID in 15 of the 50 collated cases. The lesions presented as red-brownish nodules and infiltrated ulcerative plaques, predominantly on the face and limbs. Scleroderma-like infiltration on a single limb was observed in 10% of the cases. The associated PID was ataxia-telangiectasia (52%), combined immunodeficiency (24%), cartilage-hair hypoplasia (6%) and other subtypes (18%). The granulomas were mostly sarcoidal, tuberculoid, palisaded or undefined subtypes. In some patients, several different histopathologic granulomatous patterns were found in the same biopsy. Some granulomas were associated with the presence of a vaccine strain of rubella virus.

CONCLUSION

Cutaneous granulomas associated with a PID have a variable clinical presentation. A PID can be suspected when crusty, brownish lesions are found on the face or limbs. The concomitant presence of several histological subtypes in a single patient is suggestive of a PID.

Clinical Heterogeneity of Immune Dysregulation, Polyendocrinopathy, Enteropathy, X-Linked Syndrome: A French Multicenter Retrospective Study

Objective

Immune dysregulation, polyendocrinopathy, enteropathy, X-linked (IPEX) syndrome is an autoimmune disease caused by mutations in the forkhead box protein 3 gene (FOXP3), which encodes a key regulator of immune tolerance. The aim of this study was to describe the clinical heterogeneity of the disease in a national French cohort.

Methods

Multicenter retrospective study of patients diagnosed with IPEX syndrome caused by mutations in FOXP3.

Results

Thirty children from 26 families were included. Age at disease onset (median [first to third quartile]) was 1.5 mo [0–84] and at death 3.5 years [0–10.5] (n = 15) indicating a high heterogeneity. Initial presentation was diarrhoea (68%), type 1 diabetes (T1D; 25%), skin lesions (7%) and nephropathy (3%). During the course of the disease the following main symptoms were observed: diarrhoea (100%), skin lesions (85%), T1DM (50%), severe food allergies (39%), haematological disorders (28%), nephropathies (25%), hepatitis (14%) as well as the presence of a variety of autoantibodies. Immunosuppressive mono- or combination therapy led to improvement in eight children. Three boys displayed a stable disease course without any immunosuppressive medication. Overall 10-year survival rate was 43% (42% in transplanted patients and 52% in patients on immunosuppressive therapy). Five out of 22 identified FOXP3 mutations have not been described yet: c.−23 + 1G > A, c.−23 + 5G > A, c.264delC, c.1015C > T and c.1091A > G. The first two produced atypical, attenuated phenotypes. Missense and frameshift mutations affecting the forkhead domain were associated with poor survival (Gehan–Wilcoxon p = 0.002).

Conclusion

The broad phenotypic heterogeneity of IPEX raises questions about modifying factors and justifies early FOXP3 sequencing in suspected cases.

[Malignant infantile osteopetrosis: Case report of a 5-month-old boy]

Malignant infantile osteopetrosis is a rare congenital disease characterized by a dysfunction of osteoclasts followed by an abnormal bone densification. We report the case of a 5-month-old infant in whom this disease was suspected because of the clinical (hepatosplenomegaly, gingival hypertrophy), hematological (pancytopenia and hypocalcemia), and radiological criteria (abnormal bone density, periosteal reaction). The genetic investigation confirmed the diagnosis. Compound heterozygous mutations in the CLCN7 gene were identified, including an as yet undescribed mutation. The second mutation had already been described as being responsible for severe and irreversible neurological damage in patients with osteopetrosis. Since this patient presented severely delayed development, he was not eligible for bone marrow transplantation.

CNS involvement at the onset of primary hemophagocytic lymphohistiocytosis

OBJECTIVES

To differentiate onset of CNS involvement in primary hemophagocytic lymphohistiocytosis (HLH) from that of other CNS inflammatory diseases and to identify early symptoms linked to abnormal cognitive outcome.

METHODS

Forty-six children with primary HLH who had neurologic evaluation within 2 weeks and brain MRI within 6 months of diagnosis were included. Initial symptoms, CSF study, brain MRI, and neurologic outcome were assessed. Brain MRIs were compared with those of 44 children with acute disseminated encephalomyelitis (ADEM).

RESULTS

At disease onset, 29 children (63%) had neurologic symptoms and 7 (15%) had microcephaly. Twenty-three (50%) children had abnormal CSF study, but only 15 (33%) had abnormal brain MRI. The latter showed that patients with HLH, unlike patients with ADEM, had symmetric periventricular lesions, without thalamic and brainstem involvement and with infrequent hyposignal intensity on T1. At the end of follow-up (3.6 ± 3.6 years), 17 of the 28 (61%) surviving patients had normal neurologic status, 5 (18%) had a severe neurologic outcome, and 6 (21%) had mild cognitive difficulties. Abnormal neurologic outcome was not influenced by age or type of genetic defect, but by the presence of neurologic symptoms, MRI lesions, or abnormal CSF study at onset. Early clinical and MRI symptoms may regress after treatment.

CONCLUSION

Neurologic symptoms are frequent at the onset of primary HLH and are mostly associated with abnormal CSF findings, but with normal brain MRI. In cases of abnormal brain MRI, the observed lesions differ from those of ADEM.

Hematopoietic stem cell transplantation in Omenn syndrome: a single-center experience

We retrospectively analyzed the outcome of hematopoietic stem cell transplantations (HSCT) performed at our Center between 1991 and 2002 in 11 unselected patients with Omenn syndrome, a variant of severe combined immunodeficiency. The patients' mean age at the time of the first HSCT was 8.4 months. Two patients received two, and one patient three, HSCT procedures. The resulting 15 HSCT derived in seven cases from HLA-haploidentical parents, in four patients from matched unrelated donors, in three cases from an HLA phenotypically identical related donor, and in one case from an HLA genotypically identical family donor. Nine out of 11 patients are alive and immunoreconstituted 30-146 months after transplantation. At the time of the most recent evaluation, all of the nine survivors had normal T-cell function, and eight of them had developed normal antibody production. This study demonstrates an overall mortality of 18.2%, which is substantially lower than previously reported. Early recognition of OS, rapid initiation of adequate supportive treatment and HSCT lead to improved outcome for this otherwise fatal disease, regardless of the origin and matching of hematopoietic stem cells.

Aspergillus antigen and PCR assays in bone marrow transplanted children

Screening for Aspergillus antigen and DNA has been introduced for the early diagnosis of invasive aspergillosis (IA) in adults, but data in children at risk are scarce. Seventeen 1-108 month-old children were screened for Aspergillus antigenaemia by a commercial assay before and after bone marrow transplantation (BMT). Seventy-one serum samples were examined retrospectively by a novel nested PCR assay. Results of both assays were correlated with clinical, radiological and microbiological findings used for the definition of invasive aspergillosis by the European Organisation for Research and Treatment of Cancer (EORTC). Three cases of probable or possible IA were defined, and in 14 children invasive aspergillosis was ruled out. In 10 children, Aspergillus antigen was detected in at least two consecutive serum samples, a microbiological EORTC criteria of IA. Specific DNA was detected in 8 antigen-positive and 2 antigen-negative sera. A positive predictive value of 20% was calculated for both assays. Hence, a high rate of positive results of antigen Elisa and PCR assays in BMT children are due to transient antigenaemia and fungaemia without clinical relevance. According to our data, prospective studies in well defined pediatric patients are urgently needed to determine the value of serial Aspergillus PCR assays for the early diagnosis of invasive aspergillosis in children at risk.

Identical mutations in RAG1 or RAG2 genes leading to defective V(D)J recombinase activity can cause either T-B-severe combined immune deficiency or Omenn syndrome

Omenn syndrome (OS) is an inherited disorder characterized by an absence of circulating B cells and an infiltration of the skin and the intestine by activated oligoclonal T lymphocytes, indicating that a profound defect in the lymphoid developmental program could be accountable for this condition. Inherited mutations in either the recombination activating genes RAG1 or RAG2, resulting in partial V(D)J recombinase activity, were shown to be responsible for OS. This study reports on the characterization of new RAG1/2 gene mutations in a series of 9 patients with OS. Given the occurrence of the same mutations in patients with T-B-severe combined immune deficiency or OS on 3 separate occasions, the proposal is made that an additional factor may be required in certain circumstances for the development of the Omenn phenotype. The nature of this factor is discussed.

Artemis, a novel DNA double-strand break repair/V(D)J recombination protein, is mutated in human severe combined immune deficiency

The V(D)J recombination process insures the somatic diversification of immunoglobulin and antigen T cell receptor encoding genes. This reaction is initiated by a DNA double-strand break (dsb), which is resolved by the ubiquitously expressed DNA repair machinery. Human T-B-severe combined immunodeficiency associated with increased cellular radiosensitivity (RS-SCID) is characterized by a defect in the V(D)J recombination leading to an early arrest of both B and T cell maturation. We previously mapped the disease-related locus to the short arm of chromosome 10. We herein describe the cloning of the gene encoding a novel protein involved in V(D)J recombination/DNA repair, Artemis, whose mutations cause human RS-SCID. Protein sequence analysis strongly suggests that Artemis belongs to the metallo-beta-lactamase superfamily.

Three-dimensional clustering of human RAG2 gene mutations in severe combined immune deficiency

The V(D)J recombination, which leads to the somatic rearrangement of variable, diversity, and joining segments, is the mechanism accountable for the diversity of T cell receptor- and Ig-encoding genes. The products of the RAG1 and RAG2 genes are the lymphoid-specific factors responsible for the initiation of the V(D)J recombination through the generation of a DNA double strand break. RAG1 or RAG2 gene inactivation in the mouse leads to abortion of the V(D)J rearrangement process, early block in both T and B cell maturation, and, ultimately, to severe combined immune deficiency (SCID). A human SCID condition is also characterized by an absence of mature T and B lymphocytes and is associated with mutations in either RAG1- or RAG2-encoding genes. Based on the predicted beta-propeller three-dimensional structure model for RAG2, we found that six out of the seven mutations described to date in T-B-SCID patients are clustered on one side of the propeller, in regions exposed to solvent. This finding reinforces the biological significance of this predicted model and suggests that RAG1 interacts with RAG2 on one of the side of the scaffold formed by the beta-propeller.

A new gene involved in DNA double-strand break repair and V(D)J recombination is located on human chromosome 10p

V(D)J recombination, accountable for the diversity of T cell receptor- and immunoglobulin-encoding genes, is initiated by a lymphoid-specific DNA double-strand break. The general DNA repair machinery is responsible for the resolution of this break. Any defect in one of the known components of the DNA repair/V(D)J recombination machinery (Ku70, Ku80, DNA-PKcs, XRCC4 and DNA ligase IV) leads to abortion of the V(D)J rearrangement process, early block in both T and B cell maturation, and ultimately to severe combined immune deficiency (SCID) in several animal models. A human SCID condition is also characterized by an absence of mature T and B lymphocytes, and is associated with an increase in sensitivity to DNA-damaging agents (RS-SCID). None of the above-mentioned genes are defective in these patients, arguing for the likelihood of the existence of yet another unknown component of the V(D)J recombination/DNA repair apparatus. Athabascan-speaking (SCIDA) Navajo and Apache Native Americans have a very high incidence of T(-)B(-)SCID. The SCIDA locus is highly linked with markers on chromosome 10p, although the exact molecular defect has not been recognized in these patients. We show here that cells with the SCIDA defect are impaired in the DNA repair phase of V(D)J recombination similarly to RS-SCID, precisely an absence of V(D)J coding joint formation. Moreover, genotyping analysis in several RS-SCID families corroborates a linkage of the RS-SCID locus to the SCIDA region on chromosome 10p. These results demonstrate the presence of a new essential DNA repair/V(D)J recombination gene in this region, the mutation of which causes RS-SCID in humans.

A human severe combined immunodeficiency (SCID) condition with increased sensitivity to ionizing radiations and impaired V(D)J rearrangements defines a new DNA recombination/repair deficiency

The products of recombination activating gene (RAG)1 and RAG2 initiate the lymphoid-specific phase of the V(D)J recombination by creating a DNA double-strand break (dsb), leaving hairpin-sealed coding ends. The next step uses the general DNA repair machinery of the cells to resolve this dsb. Several genes involved in both V(D)J recombination and DNA repair have been identified through the analysis of in vitro mutants (Chinese hamster ovary cells) and in vivo situations of murine and equine severe combined immunodeficiency (scid). These studies lead to the description of the Ku-DNA-dependent protein kinase complex and the XRCC4 factor. A human SCID condition is characterized by an absence of B and T lymphocytes. One subset of these patients also demonstrates an increased sensitivity to the ionizing radiation of their fibroblasts and bone marrow precursor cells. This phenotype is accompanied by a profound defect in V(D)J recombination with a lack of coding joint formation, whereas signal joints are normal. Functional and genetic analyses distinguish these patients from the other recombination/repair mutants, and thus define a new group of mutants whose affected gene(s) is involved in sensitivity to ionizing radiation and V(D)J recombination.