Background SCID is a syndrome characterized by profound T cell deficiency. BCG vaccine is contraindicated in SCID patients. Because most countries encourage BCG vaccination at birth, a high percent of SCID patients are vaccinated before their immune defect is detected. Objectives To describe the complications and risks associated with BCG vaccination in SCID patients. Methods An extensive standardized questionnaire evaluating complications, therapeutics, and outcome regarding BCG in patients diagnosed with SCID was widely distributed. Summary statistics and association analysis was performed. Results Data on 349 BCG vaccinated SCID patients from 28 centers in 17 countries was analyzed. Fifty-one percent of the patients developed BCG complications, 34% disseminated and 17% localized (a 33,000 and 400 fold increase, respectively, over the general population). Patients receiving early vaccination (≤ 1 month) showed an increased prevalence of complications (p=0.006) and death due to BCG complications (p<0.0001). The odds of experiencing complications among patients with T cells ≤ 250/uL at diagnosis was 2.1 times higher (95% CI, 1.4-3.4; p = 0.001) than among those with T cells > 250/uL. BCG complications were reported in 2/78 patients who received anti-mycobacterial therapy while asymptomatic and no deaths due to BCG complications occurred in this group. In contrast 46 BCG-associated deaths were reported among 160 patients treated with anti-mycobacterial therapy for a symptomatic BCG infection (p<0.0001). Conclusions BCG vaccine has a very high rate of complications in SCID patients, which increase morbidity and mortality rates. Until safer and more efficient anti-tuberculosis vaccines become available, delay in BCG vaccination should be considered to protect highly vulnerable populations from preventable complications.

Summary Tuberculosis (TB), caused by Mycobacterium tuberculosis (M.tb) and a few related mycobacteria, is a devastating disease, killing more than a million individuals per year worldwide. However, its pathogenesis remains largely elusive, as only a small proportion of infected individuals develop clinical disease either during primary infection or during reactivation from latency or secondary infection. Subacute, hematogenous, and extrapulmonary disease tends to be more frequent in infants, children, and teenagers than in adults. Life-threatening primary TB of childhood can result from known acquired or inherited immunodeficiencies, although the vast majority of cases remain unexplained. We review here the conditions conferring a predisposition to childhood clinical diseases caused by mycobacteria, including not only M.tb but also weakly virulent mycobacteria, such as BCG vaccines and environmental mycobacteria. Infections with weakly virulent mycobacteria are much rarer than TB, but the inherited and acquired immunodeficiencies underlying these infections are much better known. Their study has also provided genetic and immunological insights into childhood TB, as illustrated by the discovery of single-gene inborn errors of IFN-γ immunity underlying severe cases of TB. Novel findings are expected from ongoing and future human genetic studies of childhood TB in countries that combine a high proportion of consanguineous marriages, a high incidence of TB, and an excellent clinical care, such as Iran, Morocco, and Turkey.

Biallelic mutations in the genes encoding CD27 or its ligand CD70 underlie inborn errors of immunity characterized predominantly by EBV-associated immune dysregulation, such as chronic viremia, severe infectious mononucleosis, hemophagocytic lymphohistiocytosis (HLH), lymphoproliferation and malignancy. A comprehensive understanding of the natural history, immune characteristics and transplant outcomes has remained elusive. Here, in a multi-institutional global collaboration, we collected clinical information of 49 patients from 29 families (CD27 n=33, CD70 n=16), including 24 previously unreported individuals and identified a total of 16 distinct mutations in CD27, and 8 in CD70, respectively. The majority (90%) of patients were EBV+ at diagnosis, but only ~30% presented with infectious mononucleosis. Lymphoproliferation and lymphoma were the main clinical manifestations (70% and 43%, respectively), and 9 of the CD27-deficient patients developed HLH. Twenty-one (43%) patients developed autoinflammatory features including uveitis, arthritis and periodic fever. Detailed immunological characterization revealed aberrant generation of memory B and T cells, including a paucity of EBV-specific T cells, and impaired effector function of CD8+ T cells, thereby providing mechanistic insight into cellular defects underpinning the clinical features of disrupted CD27/CD70 signaling. Nineteen patients underwent allogeneic hematopoietic stem cell transplantation (HSCT) prior to adulthood predominantly because of lymphoma, with 95% survival without disease recurrence. Our data highlight the marked predisposition to lymphoma of both CD27- and CD70-deficient patients. The excellent outcome after HSCT supports the timely implementation of this treatment modality particularly in patients presenting with malignant transformation to lymphoma.

Analysis of the TCRα repertoire is particularly appropriate in a prospective way to identify patients with partial immune defects caused by suboptimal V(D)J recombination activity, a DNA repair defect, or both. It also constitutes a valuable tool for the retrospective in vivo functional validation of variants identified through exome or panel sequencing. Its broader implementation might be of interest to assist early diagnosis of patients presenting with hypomorphic DNA repair defects inclined to experience acute toxicity during prehematopoietic stem cell transplantation conditioning.

GER and atopy should be investigated in patients with recurrent spasmodic croup. Recurrent croup is a non-specific manifestation of atopy. Patients with atopy should be followed closely for developing bronchial asthma.

Severe combined immunodeficiency (SCID) has a diverse genetic aetiology, where a clinical phenotype, caused by single and/or multiple gene variants, can give rise to multiple presentations. The advent of next‐generation sequencing (NGS) has recently enabled rapid identification of the molecular aetiology of SCID, which is crucial for prognosis and treatment strategies. We sought to identify the genetic aetiology of various phenotypes of SCIDs and assessed both clinical and immunologic characteristics associated with gene variants. An amplicon‐based targeted NGS panel, which contained 18 most common SCID‐related genes, was contumely made to screen the patients (n = 38) with typical SCID, atypical SCID or OMENN syndrome. Allelic segregations were confirmed for the detected gene variants within the families. In total, 24 disease‐causing variants (17 known and 7 novel) were identified in 23 patients in 9 different SCID genes: RAG1 (n = 5), RAG2 (n = 2), ADA (n = 3), DCLRE1C (n = 2), NHEJ1 (n = 2), CD3E (n = 2), IL2RG (n = 3), JAK3 (n = 4) and IL7R (n = 1). The overall success rate of our custom‐made NGS panel was 60% (39.3% for NK+ SCID and 100% for NK− SCID). Incidence of autosomal‐recessive inherited genes is more frequently found in our cohort than the previously reported populations probably due to the high consanguineous marriages in Turkey. In conclusion, the custom‐made sequencing panel was able to identify and confirm the previously known and novel disease‐causing variants with high accuracy.

This is the first DADA2 patient presenting with severe neutropenia. We suggest that in patients with unexplained cytopenias combined with immunodeficiency, fevers of unknown origin and high inflammation markers, DADA2 should be considered.

Artemis, DNA ligase IV, DNA protein kinase catalytic subunit, and Cernunnos/XLF genes in nonhomologous end joining pathways of DNA repair mechanisms have been identified as responsible for radiosensitive SCID. Here, we present a 3-year-old girl patient with severe growth retardation, bird-like face, recurrent perianal abscess, pancytopenia, and polydactyly. Firstly, she was thought as Fanconi anemia and spontaneous DNA breaks were seen on chromosomal analysis. After that DEB test was found to be normal and Fanconi anemia was excluded. Because of that she had low IgG and IgA levels, normal IgM level, and absence of B cells in peripheral blood; she was considered as primary immunodeficiency, Nijmegen breakage syndrome. A mutation in NBS1 gene was not found; then Cernunnos/XLF deficiency was investigated due to clinical similarities with previously reported cases. Homozygous mutation in Cernunnos/XLF gene (NHEJ1) was identified. She is now on regular IVIG prophylaxis and has no new infection. Fully matched donor screening is in progress for bone marrow transplantation which is curative treatment of the disease. In conclusion, the patients with microcephaly, bird-like face, and severe growth retardation should be evaluated for hypogammaglobulinemia and primary immunodeficiency diseases.