Janus kinase-3 (JAK3) deficiency, first described in 1995, is an autosomal recessive inborn error of immunity that mostly results in variants of severe combined immunodeficiency (SCID). The frequency is estimated to account for 7-14% of heritable SCID, with sporadic cases in the Western world. Neither preferential “hot spots” nor founder effects have yet been documented. Hereby, we aim to describe the global experience of JAK3-related diseases regarding clinical spectrum, genetic landscape, including founder variants and treatment strategies. We extracted clinical, genetic, and immunological data from published cases on patients with СID/SCID phenotype caused by defects in the JAK3 gene. The literature search included unpublished cases from collaborators, reports from meetings of the European Society for Immunodeficiencies (ESID), of the Clinical Immunology Society (CIS), and published data in the biomedical research search engine (PubMed) from 1995 to 2024. Our cohort includes 132 patients with 47 unique genetic defects, including 35 novel variants (18 homozygous, 17 heterozygous). The patients were from 5 continents with majority of Asian ancestry. Country of diagnosis included North America (USA [n = 42]); South America (Brazil [n = 3]); Europe (Turkey [n = 8], Hungary [n = 1], Poland [n = 6], UK [n = 5], Italy [n = 5], Israel [n = 4], Belarus [n = 4], Russian Federation [n = 3], Georgia [n = 3], Spain [n = 1], Germany [n = 1]); Asia (India [n = 16], Iran [n = 6],China [n = 4], Pakistan [n = 1], Japan [n = 1]); and Africa (Egypt [n = 16], Saudi Arabia [n = 1], Sudan [n = 1]). Forty-five (35%) of patients from the cohort were born to consanguineous parents in 31 families from Georgia (n = 3, 1-family), Russian Federation (n = 3/2-family), Sudan (n = 1), Turkey (n = 8, 5-family), Israel (n = 4, 2-family), India (n = 3, 2-family), Egypt(n = 13, 8-family), UK (n = 5, 4-family), China (n = 1), Brazil (n = 1), Spain (n = 1), Italy (n = 1), Pakistan (n = 1), and Saudi (n = 1). 13 novel founder variants are identified. The same founder variant was seen in several countries. The majority of genetic defects were homozygous (68%); 40/132 compound were heterozygous, and 2 patients had germline heterozygous gain-of-function. The variants occurred across the entire JAK3 gene with no hotspots. Only 6 (5%) of 132 cases developed Omenn syndrome. 61 patients were transplanted, 17 died at the age of 9 months (mean age 9-18 months), and 44 are alive. We describe for the first time a global cohort of JAK3 with 132 patients with founder effects in a subgroup. Patients were identified in four continents but are most common in countries with a high rate of consanguinity. Founder effect was identified in 14 regions.

Chronic granulomatous disease (CGD) is a rare inherited disorder with affected neutrophil “respiratory burst” due to defective NADPH-oxidase function. The most common form, X-linked CGD, is associated with disease manifestations also in female carriers. Increased susceptibility to infections is observed in females with skewed X-chromosome inactivation. Additionally, carriers have increased risk of autoimmunity. We analyzed clinical manifestations, evaluated respiratory burst on neutrophils (%burst), and performed lymphocytes immunophenotyping in a cohort of 10 CGD carriers (aged 26-46 years, median = 41 years). Autoimmune disorders and infections observed in 3/10 and 2/10 females, correspondently. Discoid lupus, rheumatoid arthritis, systemic lupus erythematosus, and antiphospholipid syndrome were described. 6/10 were asymptomatic; 1 female has both infections and autoimmune complications. %Burst varies from 16% to 90% (median = 38.5%): 18-72% in females with autoimmunity, 18-22 with infections, and 16-90% asymptomatic. Thus, all carriers with infections have decreased %burst, but %burst decrease does not necessarily lead to infectious manifestations. %Burst correlates with the number of switched (CD19+CD27+IgD-) and non-switched (CD19+CD27+IgD+) memory B cells (r = 0.75 and 0.68, p = 0.0001 and 0.0009), DN B cells (CD19+CD27-IgD-), and CD21 low CD38 low B cells (r = -0.76, p = 0.0001). Carriers with autoimmunity have decreased NKT cells (p = 0.04) and have a tendency to increase naïve CD4 (CD4+CD45RA+CCR7+) and CD8 (CD8+CD45RA+CCR7+) T cells and RTE (CD4+CD45RA+CD31+) (statistical significance was not reached due to small sample size). However, lymphocyte subsets usually associated with autoimmune disorders in PID (Tregs, activated/memory T cells, and CD21 low B cells) did not differ in carriers with autoimmunity from those in asymptomatic careers. Increased susceptibility to infections and B-memory cells differentiation in X-CGD female carriers are concerned with a % of neutrophils with normal NADPH-oxidase function.

Allogeneic hematopoietic stem cell transplantation (HSCT) is an established therapy for many inborn errors of immunity (IEI). The indications for HSCT have expanded over the last decade. The study aimed to collect and analyze the data on HSCT activity in IEI in Russia. The data were collected from the Russian Primary Immunodeficiency Registry and complemented with information from five Russian pediatric transplant centers. Patients diagnosed with IEI by the age of 18 years and who received allogeneic HSCT by the end of 2020 were included. From 1997 to 2020, 454 patients with IEI received 514 allogeneic HSCT. The median number of HSCTs per year has risen from 3 in 1997–2009 to 60 in 2015-2020. The most common groups of IEI were immunodeficiency affecting cellular and humoral immunity (26

Nijmegen breakage syndrome (NBS) is a DNA repair disorder characterized by combined immunodeficiency and a high predisposition to lymphoid malignancies. The majority of NBS patients are identified with a homozygous five base pair deletion in the Nibrin (NBN) gene (c.657_661del5, p.K219fsX19) with a founder effect observed in Caucasian European populations, especially of Slavic origin. We present here an analysis of a cohort of 136 NBS patients of Eastern Slav origin across Belarus, Ukraine, Russia, and Latvia with a focus on understanding the geographic distribution, incidence of malignancy, and treatment outcomes of this cohort. Our analysis shows that Belarus had the highest prevalence of NBS (2.3 per 1,000,000), followed by Ukraine (1.3 per 1,000,000), and Russia (0.7 per 1,000,000). Of note, the highest concentration of NBS cases was observed in the western regions of Belarus and Ukraine, where NBS prevalence exceeds 20 cases per 1,000,000 people, suggesting the presence of an “Eastern Slavic NBS hot spot.” The median age at diagnosis of this cohort ranged from 4 to 5 years, and delay in diagnosis was more pervasive in smaller cities and rural regions. A total of 62 (45%) patients developed malignancies, more commonly in males than females (55.2 vs. 34.2%; p=0.017). In 27 patients, NBS was diagnosed following the onset of malignancies (mean age: 8 years). Malignancies were mostly of lymphoid origin and predominantly non-Hodgkin lymphoma (NHL) (n=42, 68%); 38% of patients had diffuse large B-cell lymphoma. The 20-year overall survival rate of patients with malignancy was 24%. However, females with cancer experienced poorer event-free survival rates than males (16.6% vs. 46.8%, p=0.036). Of 136 NBS patients, 13 underwent hematopoietic stem cell transplantation (HSCT) with an overall survival of 3.5 years following treatment (range: 1 to 14 years). Indications for HSCT included malignancy (n=7) and immunodeficiency (n=6). Overall, 9% of patients in this cohort reached adulthood. Adult survivors reported diminished quality of life with significant physical and cognitive impairments. Our study highlights the need to improve timely diagnosis and clinical management of NBS among Eastern Slavs. Genetic counseling and screening should be offered to individuals with a family history of NBS, especially in hot spot regions.

Background: Variants in recombination-activating genes (RAG) are common genetic causes of autosomal recessive forms of combined immunodeficiencies (CID) ranging from severe combined immunodeficiency (SCID), Omenn syndrome (OS), leaky SCID, and CID with granulomas and/or autoimmunity (CID-G/AI), and even milder presentation with antibody deficiency. Objective: We aim to estimate the incidence, clinical presentation, genetic variability, and treatment outcome with geographic distribution of patients with the RAG defects in populations inhabiting South, West, and East Slavic countries. Methods: Demographic, clinical, and laboratory data were collected from RAG-deficient patients of Slavic origin via chart review, retrospectively. Recombinase activity was determined in vitro by flow cytometry-based assay. Results: Based on the clinical and immunologic phenotype, our cohort of 82 patients from 68 families represented a wide spectrum of RAG deficiencies, including SCID (n = 20), OS (n = 37), and LS/CID (n = 25) phenotypes. Sixty-seven (81.7%) patients carried RAG1 and 15 patients (18.3%) carried RAG2 biallelic variants. We estimate that the minimal annual incidence of RAG deficiency in Slavic countries varies between 1 in 180,000 and 1 in 300,000 live births, and it may vary secondary to health care disparities in these regions. In our cohort, 70% (n = 47) of patients with RAG1 variants carried p.K86Vfs*33 (c.256_257delAA) allele, either in homozygous (n = 18, 27%) or in compound heterozygous (n = 29, 43%) form. The majority (77%) of patients with homozygous RAG1 p.K86Vfs*33 variant originated from Vistula watershed area in Central and Eastern Poland, and compound heterozygote cases were distributed among all Slavic countries except Bulgaria. Clinical and immunological presentation of homozygous RAG1 p.K86Vfs*33 cases was highly diverse (SCID, OS, and AS/CID) suggestive of strong influence of additional genetic and/or epigenetic factors in shaping the final phenotype. Conclusion: We propose that RAG1 p.K86Vfs*33 is a founder variant originating from the Vistula watershed region in Poland, which may explain a high proportion of homozygous cases from Central and Eastern Poland and the presence of the variant in all Slavs. Our studies in this cohort of RAG1 founder variants confirm that clinical and immunological phenotypes only partially depend on the underlying genetic defect. As access to HSCT is improving among RAG-deficient patients in Eastern Europe, we anticipate improvements in survival.

BACKGROUND: Although autoimmunity and hyperinflammation secondary to recombination activating gene (RAG) deficiency have been associated with delayed diagnosis and even death, our current understanding is limited primarily to small case series. OBJECTIVE: Understand the frequency, severity, and treatment responsiveness of autoimmunity and hyperinflammation in RAG deficiency. METHODS: In reviewing the literature and our own database, we identified 85 patients with RAG deficiency, reported between 2001 and 2016, and compiled the largest case series to date of 63 patients with prominent autoimmune and/or hyperinflammatory pathology. RESULTS: Diagnosis of RAG deficiency was delayed a median of 5 years from the first clinical signs of immune dysregulation. Most patients (55.6%) presented with more than 1 autoimmune or hyperinflammatory complication, with the most common etiologies being cytopenias (84.1%), granulomas (23.8%), and inflammatory skin disorders (19.0%). Infections, including live viral vaccinations, closely preceded the onset of autoimmunity in 28.6% of cases. Autoimmune cytopenias had early onset (median, 1.9, 2.1, and 2.6 years for autoimmune hemolytic anemia, immune thrombocytopenia, and autoimmune neutropenia, respectively) and were refractory to intravenous immunoglobulin, steroids, and rituximab in most cases (64.7%, 73.7%, and 71.4% for autoimmune hemolytic anemia, immune thrombocytopenia, and autoimmune neutropenia, respectively). Evans syndrome specifically was associated with lack of response to first-line therapy. Treatment-refractory autoimmunity/ hyperinflammation prompted hematopoietic stem cell transplantation in 20 patients. CONCLUSIONS: Autoimmunity/hyperinflammation can be a presenting sign of RAG deficiency and should prompt further evaluation. Multilineage cytopenias are often refractory to immunosuppressive treatment and may require hematopoietic cell transplantation for definitive management. (C) 2019 The Authors. Published by Elsevier Inc. on behalf of the American Academy of Allergy, Asthma & Immunology.

Background: X-linked lymphoproliferative disease type I (XLP I) is caused by mutations in the SH2D1A gene and characterized mainly by hypogammaglobulinemia and abnormal response to Epstein-Barr virus with a high predisposition to B-cell non-Hodgkin lymphoma development.Observations: In this article, we describe the experience of 2 centers in Belarus and in Russia that follow 3 male patients who were diagnosed with XLP I after lymphoma development and treatment. Three novel mutations c.51G>C (p. E17D), c. 192G>T (p. W64C), and c. 53insA (p. K18KfsX67) were found in 3 males patients with XLP I. Two of them did not have any signs of immunodeficiency before B-cell non-Hodgkin lymphoma development.Conclusions: We propose SH2D1A mutational screening be considered in male patients with or without hypogammaglobulinemia who received rituximab treatment for lymphoma and did not recover immunoglobulin G in a year after B-depleting therapy.

Background: The Wiskott-Aldrich syndrome (WAS) including X-linked thrombocytopenia (XLT) is a complex disorder with a wide range of disease severity and unique hematological and immunological manifestations. Based on this complexity, several approaches are available to these patients, including observation, symptomatic treatment, splenectomy, gene therapy (GT), or allogeneic hematopoietic stem cell transplantation (HSCT). In many instances more than one of these therapeutic options may seem appropriate for any given patient. A prospective, randomized study comparing the pros and cons of these therapeutic options in WAS/XLT would be desirable, but is not feasible due to the rarity and variable severity of the disease, as well as the need for long-term follow-up.

BACKGROUND:Omenn syndrome [Mendelian Inheritance (OMIM 603554)] is a genetic disease of the immune system, characterized by the presence of fatal generalized severe erythroderma, lymphoadenopathy, eosinophilia and profound immunodeficiency.OBJECTIVE:We studied clinical and immunologic presentation of the disease manifestation among East Slavs population with genetically confirmed Omenn syndrome.RESULTS:We collected clinical and immunologic data of 11 patients (1 from Belarus, 5--Ukraine, 5--Russia): 6 females, 5 males. The age of Omenn syndrome manifestation varied from the 1st day of life to 1 year and 1 month, the age of diagnosis--20 days to 1 year and 10 months. Nine out of 11 patients had classic immunologic phenotype T(+/-)B-NK+, 1 pt had TlowB + NK+ with CD3 + TCRgd + expansion and 1 had TlowB+/-NK+ phenotype. Eight out of 11 pts had mutation in RAG1 gene, 4 out of 8 had c.368-369delAA (p.K86fsX118) in homozygous state or heterozygous compound. In our cohort of patients, we also described two new mutations in RAG genes (p.E722Q in RAG1 and p.M459R in RAG2). At present, 7/11 were transplanted and 5 out of the transplanted are alive.CONCLUSION:This study demonstrates that the most popular genetic abnormality in East Slavs children with Omenn syndrome is c.368-369delAA (p.K86fs118) in RAG1 gene, which may be connected with more favorable prognosis because 4/4 patients survived after hematopoietic stem cells transplantation.