Diagnosis Of Severe Combined Immunodeficiency Research Articles

Paving the way in implementation of SCID newborn screening in developing nations: feasibility study and strategies to move forward in Malaysia.

Early diagnosis and effective management of Primary immunodeficiency diseases (PIDs), particularly severe combined immunodeficiency (SCID), play a crucial role in minimizing associated morbidities and mortality. Newborn screening (NBS) serves as a valuable tool in facilitating these efforts. Timely detection and diagnosis are essential for swiftly implementing isolation measures and ensuring prompt referral for definitive treatment, such as allogeneic hematopoietic stem cell transplantation. The utilization of comprehensive protocols and screening assays, including T cell receptor excision circles (TREC) and kappa-deleting recombination excision circles (KREC), is essential in facilitating early diagnosis of SCID and other PIDs, but their successful application requires clinical expertise and proper implementation strategy. Unfortunately, a notable challenge arises from insufficient funding for the treatment of PIDs. To address these issues, a collaborative approach is imperative, involving advancements in technology, a well-functioning healthcare system, and active engagement from stakeholders. The integration of these elements is essential for overcoming the existing challenges in NBS for PIDs. By fostering synergy between technology providers, healthcare professionals, and governmental stakeholders, we can enhance the efficiency and effectiveness of early diagnosis and intervention, ultimately improving outcomes for individuals with PIDs.

Relevance of lymphocyte proliferation to PHA in severe combined immunodeficiency (SCID) and T cell lymphopenia

Severe combined immunodeficiency (SCID) is characterized by a severe deficiency in T cell numbers. We analyzed data collected (n = 307) for PHA-based T cell proliferation from the PIDTC SCID protocol 6901, using either a radioactive or flow cytometry method. In comparing the two groups, a smaller number of the patients tested by flow cytometry had <10% of the lower limit of normal proliferation as compared to the radioactive method (p = 0.02). Further, in patients with CD3+ T cell counts between 51 and 300 cells/μL, there was a higher proliferative response with the PHA flow assay compared to the 3H-T assay (p < 0.0001), suggesting that the method of analysis influences the resolution and interpretation of PHA results. Importantly, we observed many SCID patients with profound T cell lymphopenia having normal T cell proliferation when assessed by flow cytometry. We recommend this test be considered only as supportive in the diagnosis of typical SCID.

Severe combined immunodeficiency diagnosis and genetic defects.

Severe combined immunodeficiency (SCID) is a rare and life-threatening genetic disorder that severely impairs the immune system's ability to defend the body against infections. Often referred to as the "bubble boy" disease, SCID gained widespread recognition due to the case of David Vetter, a young boy who lived in a sterile plastic bubble to protect him from germs. SCID is typically present at birth, and it results from genetic mutations that affect the development and function of immune cells, particularly T cells and B cells. These immune cells are essential for identifying and fighting off infections caused by viruses, bacteria, and fungi. In SCID patients, the immune system is virtually non-existent, leaving them highly susceptible to recurrent, severe infections. There are several forms of SCID, with varying degrees of severity, but all share common features. Newborns with SCID often exhibit symptoms such as chronic diarrhea, thrush, skin rashes, and persistent infections that do not respond to standard treatments. Without prompt diagnosis and intervention, SCID can lead to life-threatening complications and a high risk of mortality. There are over 20 possible affected genes. Treatment options for SCID primarily involve immune reconstitution, with the most well-known approach being hematopoietic stem cell transplantation (HSCT). Alternatively, gene therapy is also available for some forms of SCID. Once treated successfully, SCID patients can lead relatively normal lives, but they may still require vigilant infection control measures and lifelong medical follow-up to manage potential complications. In conclusion, severe combined immunodeficiency is a rare but life-threatening genetic disorder that severely compromises the immune system's function, rendering affected individuals highly vulnerable to infections. Early diagnosis and appropriate treatment are fundamental. With this respect, newborn screening is progressively and dramatically improving the prognosis of SCID.

Impact of newborn screening for SCID on the management of congenital athymia

Newborn screening (NBS) programs for severe combined immunodeficiency facilitate early diagnosis of severe combined immunodeficiency and promote early treatment with hematopoietic stem cell transplantation, resulting in improved clinical outcomes. Infants with congenital athymia are also identified through NBS because of severe T-cell lymphopenia. With the expanding introduction of NBS programs, referrals of athymic patients for treatment with thymus transplantation have recently increased at Great Ormond Street Hospital (GOSH) (London, United Kingdom). We studied the impact of NBS on timely diagnosis and treatment of athymic infants with thymus transplantation at GOSH. We compared age at referral and complications between athymic infants diagnosed after clinical presentation (n= 25) and infants identified through NBS (n= 19) who were referred for thymus transplantation at GOSH between October 2019 and February 2023. We assessed whether age at time of treatment influences thymic output at 6 and 12 months after transplantation. The infants referred after identification through NBS were significantly younger and had fewer complications, in particular fewer infections. All deaths occurred in the group of those who did not undergo NBS, including 6 patients before and 2 after thymus transplantation because of preexisting infections. In the absence of significant comorbidities or diagnostic uncertainties, timely treatment was achieved more frequently after NBS. Treatment when younger than age 4 months was associated with higher thymic output at 6 and 12 months after transplantation. NBS contributes to earlier recognition of congenital athymia, promoting referral of athymic patients for thymus transplantation before they acquire infections or other complications and facilitating treatment at a younger age, thus playing an important role in improving their outcomes.

Newborn Screening for Severe Combined Immunodeficiency

Newborn screening (NBS) for Severe Combined Immunodeficiency (SCID) has been successfully implemented in all 50 United States and Puerto Rico from 2008-2018. This life-saving screening tool has drastically improved overall survival of babies diagnosed with SCID from 74% to 96%. TREC is a stable, circular DNA molecule that is produced during the process of T-cell receptor (TCR) rearrangement and is the target of the quantitative PCR screen on Guthrie cards. Low TRECs are a marker of low naive T cell numbers. This new screening process has facilitated discovery of new genes that cause SCID, new data on patients with SCID, as well as other causes of infant lymphopenia. This new information has prompted the Primary Immune Disease Treatment Consortium to re-classify the diagnosis of SCID in 2022. Providers who are first recipients of a positive screen must understand laboratory methods of the screen, treatment recommendations and options for those with SCID as well as other relevant causes of a positive screen such as 22q11 syndrome, Ataxia Telangiectasia, prematurity. These topics are crucial to cover when reporting results to a family who is receiving unexpected news on their otherwise well appearing newborn. Prompt medical evaluation and prophylaxis have been shown to improve survival and outcomes, and providers play an essential role in relaying this information and care to families. While TREC screen has proven to be a valuable screening tool for conditions with lymphopenia, over 500 immune deficiency diseases exist, and expansion to include these diseases on the NBS could be possible with Next Generation Sequencing in the future.

Retrospective analysis of patients with severe combined immunodeficiency and alternative diagnostic criteria: A 20-year single centre experience.

Severe combined immunodeficiency (SCID) is an inborn errors of immunity (IEI) disorder characterized by impairment in the development and function of lymphocytes and could be fatal if not treated with hematopoietic stem cell transplant in the first 2 years of life. There are various diagnostic criteria for SCID among different primary immunodeficiency societies. We retrospectively evaluated clinical and laboratory findings of 59 patients followed up with the diagnosis of SCID at our clinic over the past 20 years in order to develop an algorithm that would help diagnosis of SCID for the countries where a high ratio of consanguineous marriage is present because these countries have not launched TREC assay in their newborn screening programs. The mean age at diagnosis was 5.80±4.90 months, and the delay was 3.29±3.99 months. The most common complaint and physical examination findings were cough (29.05%), eczematous rash (63%) and organomegaly (61%). ADA (17%), Artemis (14%), RAG1/2 (15%), MHC Class II (12%) and IL-2R (12%) deficiencies were the most common genetic defects. Lymphopenia (87.5%) was the most frequent abnormal laboratory finding and below 3000/mm3 in 95% of the patients. The CD3+ T cell count was 300/mm3 and below in 83% of the patients. As a result, a combination of low lymphocyte count and CD3 lymphopenia for SCID diagnosis would be more reliable for countries with high rate of consanguineous marriage. Physicians should consider diagnosis of SCID in a patient presenting with severe infections and lymphocyte counts below 3000/mm3 under 2 years of age.

A high-throughput newborn screening approach for SCID, SMA, and SCD combining multiplex qPCR and tandem mass spectrometry.

Early diagnosis of severe combined immunodeficiency (SCID), spinal muscular atrophy (SMA), and sickle cell disease (SCD) improves health outcomes by providing a specific treatment before the onset of symptoms. A high-throughput nucleic acid-based method in newborn screening (NBS) has been shown to be fast and cost-effective in the early detection of these diseases. Screening for SCD has been included in Germany's NBS Program since Fall 2021 and typically requires high-throughput NBS laboratories to adopt analytical platforms that are demanding in terms of instrumentation and personnel. Thus, we developed a combined approach applying a multiplexed quantitative real-time PCR (qPCR) assay for simultaneous SCID, SMA, and 1st-tier SCD screening, followed by a tandem mass spectrometry (MS/MS) assay for 2nd-tier SCD screening. DNA is extracted from a 3.2-mm dried blood spot from which we simultaneously quantify T-cell receptor excision circles for SCID screening, identify the homozygous SMN1 exon 7 deletion for SMA screening, and determine the integrity of the DNA extraction through the quantification of a housekeeping gene. In our two-tier SCD screening strategy, our multiplex qPCR identifies samples carrying the HBB: c.20A>T allele that is coding for sickle cell hemoglobin (HbS). Subsequently, the 2nd tier MS/MS assay is used to distinguish heterozygous HbS/A carriers from samples of patients with homozygous or compound heterozygous SCD. Between July 2021 and March 2022, 96,015 samples were screened by applying the newly implemented assay. The screening revealed two positive SCID cases, while 14 newborns with SMA were detected. Concurrently, the qPCR assay registered HbS in 431 samples which were submitted to 2nd-tier SCD screening, resulting in 17 HbS/S, five HbS/C, and two HbS/β thalassemia patients. The results of our quadruplex qPCR assay demonstrate a cost-effective and fast approach for a combined screening of three diseases that benefit from nucleic-acid based methods in high-throughput NBS laboratories.

A variant of RAG1 gene identified in severe combined immunodeficiency: a case report

BackgroundThe recombination-activating gene 1 (RAG1) protein is essential for the V (variable)-D (diversity)-J (joining) recombination process. Mutations in RAG1 have been reported to be associated with several types of immune disorders. Typical clinical features driven by RAG1 variants include persistent infections, severe lymphopenia, and decreased immunoglobulin levels .Case presentationIn this study, a 2-month-24-days-old infant with recurrent fever was admitted to our hospital with multiple infections and absence of T and B lymphocytes. The infant was diagnosed with severe combined immunodeficiency (SCID). A homozygous variation c.2147G>A (NM_000448.2: exonme2: c.2147G>A (p.Arg716Gln)) was identified in the RAG1 gene using whole-exome sequencing and Sanger sequencing. The predicted 3D structure of variant RAG1 indicated altered protein stability. Additionally, decreased expression of variant RAG1 gene was detected at both the mRNA and protein levels.ConclusionsOur study identified a novel homozygous variant in RAG1 gene that causes SCID. This finding expands the variant spectrum of RAG1 in SCID and provides further evidence for the clinical diagnosis of SCID.

Evaluation of thymopoiesis in healthy Turkish children aged 0-6 years.

Early diagnosis and effective treatment serve as life-saving procedures for primary immunodeficiencies (PIDs) which are very common and a major public health problem in Turkey. Severe combined immunodeficiency (SCID) is constitutively a T-cell defect in which naïve T-cell development is defective due to the mutations in genes responsible for the T cell differentiation and insufficient thymopoiesis. So, assessment of thymopoiesis is very important in the diagnosis of SCID and several combined immune deficiencies (CIDs). The purpose of this study is to examine thymopoiesis in healthy children via measurement of recent thymic emigrants (RTE); T lymphocytes that express CD4, CD45RA and CD31 to establish the RTE reference values in Turkish children. RTE were measured in the peripheral blood (PB) of 120 healthy infants and children between 0-6 years including cord blood samples, by flow cytometry. The absolute count of RTE cells and their relative ratios were found to be higher during the first year of life, being highest at the 6th month and tending to decrease significantly by age following birth (p=0.001). In the cord blood group, both values were lower than those in the 6-month-old group. The absolute lymphocyte count (ALC) varying by age, was found to reduce to 1850/mm³ in 4-years and after. Here we evaluated normal thymopoiesis and established the normal reference levels of RTE cells in the peripheral blood of healthy children aged between 0-6 years. We believe that the collected data will contribute to early diagnosis and monitoring of immune reconstitution; serving as an additional fast and reliable marker for many PID patients especially for SCID including many other CIDs, especially in nations where newborn screening (NBS) via T cell receptor excision circles (TREC) has not yet become available.

The diagnosis of severe combined immunodeficiency: Implementation of the PIDTC 2022 Definitions

Shearer etal in 2014 articulated well-defined criteria for the diagnosis and classification of severe combined immunodeficiency (SCID) as part of the Primary Immune Deficiency Treatment Consortium's (PIDTC's) prospective and retrospective studies of SCID. Because of the advent of newborn screening for SCID and expanded availability of genetic sequencing, revision of the PIDTC 2014 Criteria was needed. We developed and tested updated PIDTC 2022 SCID Definitions by analyzing 379 patients proposed for prospective enrollment into Protocol 6901, focusing on the ability to distinguish patients with various SCID subtypes. According to PIDTC 2022 Definitions, 18 of 353 patients eligible per 2014 Criteria were considered not to have SCID, whereas 11 of 26 patients ineligible per 2014 Criteria were determined to have SCID. Of note, very low numbers of autologous T cells (<0.05×109/L) characterized typical SCID under the 2022 Definitions. Pathogenic variant(s) in SCID-associated genes was identified in 93% of patients, with 7 genes (IL2RG, RAG1, ADA, IL7R, DCLRE1C, JAK3, and RAG2) accounting for 89% of typical SCID. Three genotypes (RAG1, ADA, and RMRP) accounted for 57% of cases of leaky/atypical SCID; there were 13 other rare genotypes. Patients with leaky/atypical SCID were more likely to be diagnosed at more than age 1 year than those with typical SCID lacking maternal T cells: 20% versus 1% (P< .001). Although repeat testing proved important, an initial CD3 T-cell count of less than 0.05×109/L differentiated cases of typical SCID lacking maternal cells from leaky/atypical SCID: 97% versus 7% (P< .001). The PIDTC 2022 Definitions describe SCID and its subtypes more precisely than before, facilitating analyses of SCID characteristics and outcomes.

The diagnosis of severe combined immunodeficiency (SCID): The Primary Immune Deficiency Treatment Consortium (PIDTC) 2022 Definitions

Severe combined immunodeficiency (SCID) results from defects in the differentiation of hematopoietic stem cells into mature T lymphocytes, with additional lymphoid lineages affected in particular genotypes. In 2014, the Primary Immune Deficiency Treatment Consortium published criteria for diagnosing SCID, which are now revised to incorporate contemporary approaches. Patients with typical SCID must have less than 0.05 × 109 autologous T cells/L on repetitive testing, with either pathogenic variant(s) in a SCID-associated gene, very low/undetectable T-cell receptor excision circles or less than 20% of CD4 T cells expressing naive markers, and/or transplacental maternally engrafted T cells. Patients with less profoundly impaired autologous T-cell differentiation are designated as having leaky/atypical SCID, with 2 or more of these: low T-cell numbers, oligoclonal T cells, low T-cell receptor excision circles, and less than 20% of CD4 T cells expressing naive markers. These patients must also have either pathogenic variant(s) in a SCID-associated gene or reduced T-cell proliferation to certain mitogens. Omenn syndrome requires a generalized erythematous rash, absent transplacentally acquired maternal engraftment, and 2 or more of these: eosinophilia, elevated IgE, lymphadenopathy, hepatosplenomegaly. Thymic stromal defects and other causes of secondary T-cell deficiency are excluded from the definition of SCID. Application of these revised Primary Immune Deficiency Treatment Consortium 2022 Definitions permits precise categorization of patients with T-cell defects but does not imply a preferred treatment strategy.

The Treatment of Primary Immune Deficiencies: Lessons Learned and Future Opportunities.

Primary immunodeficiency is a group of disorders associated with susceptibility to infectious agents and the development of various comorbidities. Many primary immunodeficiencies are complicated by immune dysregulation, autoinflammation, or autoimmunity which impacts multiple organ systems. Major advances in the treatment of these disorders have occurred over the last half-century, and deeper molecular understanding of many disorders combined with clinically available genetic testing is allowing for use of precision therapy for several primary immunodeficiencies. Patients with antibody deficiencies who rely on immunoglobulin replacement therapy now have many treatment options with products that are much safer and better tolerated compared to the past. Newborn screening for severe combined immunodeficiency, now implemented throughout the USA and in many countries worldwide, has lowered the age at which many patients are diagnosed with these diseases. Early diagnosis of severe combined immunodeficiency allows infants to proceed to definitive therapy such as stem cell transplantation or gene therapy prior to facing potentially life-threatening infections. While stem cell transplantation continues to carry significant risks, knowledge gained over recent decades is allowing for improved survival with less toxicity and less graft versus host disease.

Severe Combined Immunodeficiency (SCID) Screening in Arizona: Lessons Learned from the First 2 Years.

The incidence of severe combined immunodeficiency (SCID) in the USA was reported as 1 in 58,000 live births. In Arizona, it was anticipated that newborn screening would identify two to four cases of SCID per year. This estimate did not consider ethnic nuances in Arizona, with higher percentages of Native American and Hispanic populations compared to national percentages. The true incidence of SCID and non-SCID T cell lymphopenia has not previously been reported in Arizona. A retrospective chart review was performed on all abnormal SCID newborn screening (NBS) tests in Arizona from January 1, 2018, to December 31, 2019, using data from the Arizona Department of Health Services and the Phoenix Children's Hospital's electronic medical record [IRB# 20-025]. Seven infants were diagnosed with SCID, yielding an incidence of 1 in 22,819 live births. Four of these infants had Artemis-type SCID. Thirteen infants were identified with an abnormal initial NBS which ultimately did not lead to a diagnosis of SCID. Four of these infants were diagnosed with congenital syndromes associated with T cell lymphopenia. Infants of Hispanic ethnicity were over-represented in this cohort. Over 2years, NBS in Arizona confirmed an incidence more than 2.5 times that reported nationally. This increased incidence is likely reflective of Arizona's unique population profile, with a higher percentage of Native American population. The findings in our non-SCID cohort are in alignment with previously published data, except for an increased percentage of infants of Hispanic/Latino ethnicity, possibly reflecting Arizona's increased percentage of Hispanic/Latino population compared to the general US population.

Cytometric analysis and clinical features in a Moroccan cohort with severe combined immunodeficiency.

Severe combined immunodeficiency (SCID) is a form of primary immunodeficiency disease (PID). It is characterized by a serious abnormality of the cellular and sometimes humoral system due to a deficiency in development of T cells, B cells and/or NK cells. The early diagnosis of SCID improves the prognosis. Typically, the initial consideration of SCID is made based on low lymphocyte counts. Notwithstanding, the heterogeneity of lymphocyte count presentation makes the diagnosis of SCID a significant challenge. The objective of this cross-sectional retrospective study was to analyze the lymphocyte subpopulation counts along with clinical manifestations within a Moroccan cohort diagnosed as SCID compared to children diagnosed with non-PID diseases. Thirty-five SCID confirmed patients were selected in the period between 2008 and 2018 and compared with non-PID patients. Results of peripheral blood T, B, and NK lymphocyte subpopulation counts were measured by flow cytometry for each SCID subtype. As expected, T cell count was less than 300 cells/μL in most patients with SCID (85.5%). Unexpectedly, significantly higher T cell counts were detected in some patients with a confirmed clinical diagnosis and family history of SCID. 5.7% of our SCID Moroccan cohort had T cell numbers in the range between 300 and 500 cells/μL. 8.7% of our SCID Moroccan cohort had T cell numbers higher than 500 cells/μL. Of the SCID subtypes, the proportion of SCID with B cell deficiencies was highly represented in our cohort. 71.4% of Moroccan SCID patients (25 out of 35 patients) were of T-B-subtype. Furthermore, 40% of the patients (14 out of 35 patients) had a T-B-NK+ profile and 31.4% had a T-B-NK- profile (11 out of 35 patients). The most common clinical manifestations observed in our SCID cohort were pneumonia, failure to thrive, candidiasis, diarrhea, bronchitis and urinary tract infections. Our results not only highlight the relatively frequent presence of atypical SCID in the Moroccan population with unexpectedly high T cell numbers, but also describes the incidence pattern of common SCID subtypes in Morocco. Physicians in Morocco may find this local region-specific difference in SCID important for making improved early diagnosis of this disease.

BCG Infection in Patients With Inborn Errors of Immunity Receiving the Russian BCG Strain

Bacillus Calmette-Guierin (BCG) vaccination complications are common in inborn errors of immunity (IEI) due to the inability to clear live attenuated Mycobacterium bovis. Various BCG-vaccine strains are used worldwide, and the profile of the Russian BCG strain vaccine complications in IEI is poorly characterized. To evaluate risks of BCG infection in a large cohort of patients with IEI vaccinated with the Russian BCG strain. We evaluated 778 patients with IEI vaccinated with the Russian BCG strain. A total of 114 (15%) developed BCG infection, 41 (36%) with local, 19 (17%) with regional, and 54 with (47%) disseminated disease. BCG infection was seen in 58% of the patients with severe combined immunodeficiency (SCID), 82% with chronic granulomatous disease, 50% with innate immune defects, 5% with combined immunodeficiency, and 2% with other IEI. BCG infection presented at a median age of 4 to 5 months in SCID, chronic granulomatous disease, combined immunodeficiency, and other IEI groups versus 12 months in patients with innate immune defects (P < .005). We found no influence of specific genetic defects, CD3+ and natural killer cell numbers in SCID, or dihydrorhodamine test stimulation index values in chronic granulomatous disease on the BCG-infection risks. All patients with SCID received antimycobacterial therapy at SCID diagnosis even in the absence of active BCG infection. More antimycobacterial agents were required in disseminated relative to local or regional infection (P < .0001). Only 1 of 114 patients (with SCID) died of BCG-related complications (<1%). BCG infection is common in patients with IEI receiving BCG vaccination. Rational early antimycobacterial therapy, combined with anticytokine agents for posttransplant inflammatory syndrome prevention, and treatment in SCID may prevent BCG-related mortality.

Hematopoietic Stem Cell Transplantation in Patients with Severe Combined Immunodeficiency: A Single-Center Experience

Objective: The aim of this study was to determine the factors affecting outcomes in patients who underwent hematopoietic stem cell transplantation (HSCT) with the diagnosis of severe combined immunodeficiency (SCID). Furthermore, our aim is to share our singlecenter experience of HSCT among SCID patients. Materials and Methods: The data of patients who underwent HSCT with the diagnosis of SCID between January 2014 and January 2021 in the pediatric bone marrow transplant unit of Istanbul Medipol University were retrospectively analyzed. Demographic and clinical data, treatment regimens, donor source, type of transplantation, pre- and post-transplantation infections, and complications were evaluated. Results: Among fifteen patients who underwent HSCT, 5 (33%) were female. The mean age at diagnosis was 3 months (1-6 months), and at transplantation 6 months (3-10 months). The mean time from diagnosis to transplantation was 3 months (2-9 months). There was a history of consanguineous marriage in thirteen (87%) and sibling death in eight (53%) cases. As donors, six (40%) were siblings and five (33%) were unrelated, while four (27%) patients underwent haploid transplantation. Four (27%) patients died during the first 100 days of transplantation. The median follow-up period was 23 months (9-61 months). Overall survival probability was calculated as 73%. Conclusion: SCID should be considered as an emergency in pediatrics. Devastating complications, including severe organ damage, lifethreatening infections, and even death, could appear in case of diagnostic delay. HSCT is a currently available curative treatment option. Subjects with a confirmed diagnosis should be referred to the appropriate bone marrow transplant center and treated as soon as possible.

Infection in Infants With SCID: Isolation, Infection Screening, and Prophylaxis in PIDTC Centers

To identify the types and timing of infections in infants with severe combined immunodeficiency (SCID), who were either diagnosed by newborn screen (NBS) or family history (FH), before hematopoietic stem cell transplant (HSCT). Additionally, in the study, the researchers assessed infection prevention management practices used by Primary Immune Deficiency Treatment Consortium (PIDTC) centers in SCID infants before HSCT.In this study, we included 59 infants diagnosed with SCID via NBS or FH who underwent HSCT (PIDTC protocol 6901) among 25 different PIDTC centers between 2010–2014.This study had 2 parts. Part 1 was a retrospective chart review in which researchers evaluated age at SCID diagnosis, method of diagnosis (NBS versus FH), age at infection onset, type and frequency of infection(s), time to HSCT, and outcomes. Part 2 was a 29-question survey administered to 42 PIDTC centers inquiring about their pre-HSCT management practices for SCID infants. With the survey, the researchers assessed infection prevention management practices including location (inpatient versus outpatient), antimicrobial prophylaxis, immunoglobulin therapies, and practices for monitoring and preventing viral infections.Part 1 (infection and survival outcomes) results were as follows: Among the 59 infants diagnosed with SCID, 64% were diagnosed via NBS, and 36% were diagnosed via FH. Infants with FH were diagnosed significantly earlier than those diagnosed by NBS (median: 6 days versus 25 days, respectively; P < .001). Patients diagnosed via NBS were more likely to experience at least 1 pre-HSCT infection, compared with those diagnosed by FH (55% vs 19%; P = .012) and had higher infection density (0.3 per month versus 0.1 per month; P = .029). The rate of active infection at the time of HSCT was higher in patients diagnosed by NBS (39% vs 5%; P = .005). The location of pre-HSCT management (outpatient versus inpatient) did not impact infection rates. The most common infections reported in both groups were cytomegalovirus, Epstein-Barr virus, and respiratory viruses. The median time to HSCT was significantly longer in those diagnosed by NBS, compared with that of those diagnosed by FH (96.5 days versus 49 days; P < .001). Two-year survival post-HSCT was comparable (89%) in both groups. Part 2 (survey) results were as follows: 50 physicians from 42 PIDTC centers completed the survey with 100% response rate. Initiation of SCID management was started at a median age of 21 days. There were variable recommendations on location of pre-HSCT management, although 31% routinely planned for inpatient care and 17% routinely planned for outpatient care. Inpatient hygiene measures were variable, but most (70%) recommended reverse isolation with (50%) or without (20%) positive pressure ventilation. Most centers (79%) restricted nonstaff caregivers to 2 individuals. Antimicrobial prophylaxis was recommended against Pneumocystis jiroveci universally (most commonly, trimethoprim-sulfamethoxazole: 91%), although the age at initiation varied. Fungal prophylaxis was routinely started by 79%, although the timing and agent varied. Most providers (98%) used immunoglobulin, although routes varied. A minority of centers (45%) routinely recommended viral prophylaxis with acyclovir. Routine viral screening was performed for cytomegalovirus at 93% of centers, whereas monitoring for other viruses (Epstein-Barr virus and adenovirus) was not consistent.Infants diagnosed with SCID via FH were diagnosed sooner, were less likely to develop infection pre-HSCT, and had a shorter time to HSCT, when compared with those diagnosed by NBS. Despite this, 2-year survival post-HSCT was the same. Pre-HSCT medical management was variable among PIDTC centers, specifically the location of pre-HSCT management outpatient versus that of inpatient.T-cell receptor excision circle analysis is an easy and efficient way to screen for SCID and now part of the NBS in all 50 states. Because of this, we are now able to diagnose and intervene early for SCID infants, greatly improving these vulnerable patients’ clinical outcomes. Despite this, when comparing infants diagnosed with SCID by NBS with those diagnosed by FH, NBS falls short. In this study, the authors found that infants diagnosed with SCID by NBS had a longer time to diagnosis and HSCT, had a higher infection density, and were more likely to be infected at time of HSCT. Although all 50 states screen for SCID on NBS, it is clear there is more work to be done to streamline evaluation and management to reduce delays to and infections before HSCT. Additionally, there is robust data supporting early HSCT to improve clinical outcomes, but even at PIDTC centers, pre-HSCT management practices for SCID infants is variable. Clinicians would benefit from more uniform SCID management guidelines in the future.

Reticular Dysgenesis: A Rare Immunodeficiency in a Neonate With Cytopenias and Bacterial Sepsis.

Severe combined immunodeficiency (SCID) consists of a group of disorders defined by abnormal B and T cell development that typically results in death within the first year of life if undiagnosed or untreated. Reticular dysgenesis (RD) is a rare but especially severe form of SCID that is caused by adenylate kinase 2 deficiency and is characterized not only by lymphopenia but also by profound neutropenia. RD predisposes patients to viral and fungal infections typical of SCID as well as serious bacterial infections atypical in the neonatal period in other SCID types. RD is also associated with sensorineural hearing loss not typically seen in other forms of SCID. Without rapid diagnosis and curative hematopoietic stem cell transplantation, RD is fatal within days to months due to overwhelming bacterial infection. The inclusion of the T cell receptor excision circle assay nationally in 2017 on the newborn screen has facilitated diagnosis of SCID in the neonatal period. This case reports on a male infant with RD who presented after preterm birth with severe cytopenias and a gastrointestinal anomaly and ultimately developed severe bacterial sepsis. Postmortem bone marrow evaluation and panel-based gene sequencing identifying 2 novel variants in the adenylate kinase 2 gene provided confirmation for a diagnosis of RD. This case emphasizes the importance of thorough diagnostic evaluation, including the newborn screen, in neonates and infants with persistent and unexplained cytopenias. Prompt hematology and/or immunology referral is advised for disease management and to facilitate hematopoietic stem cell transplantation to optimize long-term survival.

Ten Years of Newborn Screening for Severe Combined Immunodeficiency (SCID) in Massachusetts

To examine the outcomes of population newborn screening (NBS) for severe combined immunodeficiency (SCID) by using T-cell receptor excision circles (TRECs) after the first decade of implementation in Massachusetts.Infants born in Massachusetts screened through the New England Newborn Screening Program between February 1, 2009, and January 31, 2019.The authors present a population cohort of infants receiving NBS for SCID, both before and after mandatory NBS implementation in 2016.Of 720 038 infants screened, normal TRECs were identified in 99.71%. At least 1 abnormal specimen was identified in 2072 infants (0.29% of those screened). Of these infants, 1771 had an additional TREC result, which was normal, and were released from the screening program (83.8% of those with an abnormal TREC result before confirmatory flow cytometry and 1.7% after further lymphocyte phenotyping). Further evaluation by flow cytometry occurred in 237 infants (11.4% of those with at least 1 abnormal TREC result), and low naïve T-cell percentages were associated with a greater risk of a combined immunodeficiency. A total of 9 infants were diagnosed with SCID or leaky SCID, 7 were diagnosed with other combined immunodeficiencies, and 3 were diagnosed with athymia (0.4%, 0.3%, and 0.1%, respectively. of those with an abnormal TREC screen). The incidence of SCID or leaky SCID was reported as ∼1 in 80 000; however, more broadly, the incidence of severe T-cell lymphopenia for which definitive treatment was indicated was ∼1 in 50 000 infants. All patients with SCID or leaky SCID underwent hematopoietic cell transplant or gene therapy for which survival was 100%, and 1 patient with athymia underwent a successful thymus transplant. With NBS, the researchers successfully identified all known cases of SCID. Compared with survival before NBS by TREC, survival improved significantly for infants with SCID or leaky SCID (100% [n = 9] vs 57% [n = 7]. Of 162 infants with T-cell counts <2500 but above 1500 µL, no cases of SCID were identified, but 8 infants were diagnosed with partial DiGeorge syndrome.NBS of TREC levels is highly sensitive and specific, with the ability to improve early diagnosis of SCID. When compared with historical rates of SCID diagnosis and management before TREC evaluation by NBS, screening can reduce the time to transplant (3.4 months versus 6.5 months) and improve outcomes for infants with SCID.Screening for SCID has been a significant addition to NBS programs across the country, and multiple studies have suggested this to be a cost-effective strategy. As of December 2018, all 50 states have begun to screen for SCID at birth. SCID is often unrecognized in early life, but survival improves with early diagnosis. With this study, the authors provide long-term outcomes and highlight the benefit of these programs, suggesting a 43% reduction in mortality from a condition that can be successfully treated when identified early. From these data, the sensitivity, specificity, negative predictive value, and positive predictive value can be calculated (100%, 99.7%, 100%, and 0.91%, respectively). Notably, despite high sensitivity and specificity, a population prevalence of ∼1:50 000 to 80 000 lowers the positive predictive value of screening. Although early referral to an immunologist is important in infants with abnormal TREC results, these data also suggest the absolute risk of SCID in these infants is low (<1%). Thus, when counseling families of infants with an abnormal TREC screen, there is room for cautious optimism, pending results of definitive testing. More work is needed to better understand the short- and longer-term psychosocial impacts of a false-positive NBS result for SCID on families with unaffected infants after a positive screening test result.

Rapid and Safe T Cell Immune Reconstitution By T Cell Progenitor Injection Following Haploidentical Transplantation for Severe Combined Immunodeficiency (SCID)

Severe Combined Immunodeficiencies (SCID) are defined by a complete absence of T lymphocytes in the blood and lymphoid organs, with variable defects in other WBC subsets depending on the gene defect. From a clinical perspective SCIDs are characterized by early development of life-threatening infections accounting for early death if untreated. The treatment of choice is allogeneic HSCT with very high success rates if a HLA identical sibling (MRD) or unrelated donor (MUD) is used. However, due to the scarcity of matched-related donors, SCID can benefit from haploidentical HSCT. In contrast to the continuous improvement of HLA compatible donor transplantations, no significant improvements have been obtained over the last twenty years for haploidentical HSCT. The profound immunodeficiency during the first months following haploidentical HSCT exposes patients to opportunistic viral, bacterial and fungal infections, which account for approximately 30-40% of the transplant related mortality (TRM). The rapid restoration of the T-cell compartment is the main aim of stem cell therapy in this setting. To this end we have recently set up a phase I/II clinical trial (ClinicalTrials.gov Identifier: NCT03879876) aiming to accelerate the immune reconstitution by injection of ex vivo generated Human T lymphoid progenitors (ProTcell TM) following haploidentical HSCT. T cell progenitors in this trial are generated in vitro within 7 days from mobilized peripheral blood (mPB) CD34 + hematopoietic stem and precursor cells (HSPCs) using our Notch ligand Delta-like 4 GMP culture platform so called SMART Immune's SMART101 product.This open-label, non-randomized study evaluates safety and efficacy of the SMART101 injection following CD34 + selected, haploidentical HSCT in SCID patients and is designed as a dose-escalation study comprising 6 doses of the SMART101 product obtained from the patient's haploidentical stem cell graft. The aim of this protocol is to define the highest efficacy dose without any toxicity.The conditioning regimen is based on Busulfan and Fludarabine according to IE-WP/EBMT guidelines with upfront administration of ATG to prevent graft rejection. Tight monitoring of ATG serum levels is applied in order to assure injection of SMART101 when ATG is below the lymphotoxicity threshold.Here we report the results of the first two SCID patients. P1 presented a homozygous Artemis deficiency. At diagnosis he had an ALC of 341/µl, with complete absence of T cells (CD3 + < 4/µl, CD4 + < 1/µl, CD8 + < 2/µl) and B cells (CD19 + 0/µl). NK cells were present in the normal range for age (CD16 +CD56 + 331/µl).In the absence of an HLA compatible donor, the patient's father was chosen as haploidentical stem cell donor.P1 received upfront ATG (5 mg /kg total dose), Busulfan (AUC of 16058 microM.min) and Fludarabine (160 mg/m²). He received Defibrotide prophylaxis from D0 until D+21, as well as Ursodeoxycholic acid until D+80. The CD34 + immunoselected graft contained 1.04 x 10 8 nucleated cells/kg with 24.15 x10 6 CD34 + cells/kg and 4000 CD3 + cells/kg on D0. After ATG monitoring 0.12x10 6 Smart101 cells were administered at D+14 post- HSCT.In the follow-up P1 didn't develop any acute or chronic SAEs, no acute or chronic GVHD, and no infection. He was discharged at D+121 post HSCT.The day +100 post transplantation CD4 + cell count/microliter exceeded 10 times the CD4 + count of our historical cohort of RAG1/2 or Artemis deficient patients transplanted with haploidentical HSCT alone following the same conditioning regimen.At 6 months post HSCT this difference remains important (851 versus 300 CD4 + cells/µl); Ig replacement therapy could be stopped as early as 9 months post transplantation and vaccinations have been started. At last follow up; almost 14 months post HSCT P1 is alive and well.P2 had an undefined molecular SCID diagnosis. She has been treated with the same conditioning regimen and received the second dose of 0.2x10 6 CD7 + cells, but unfortunately died from severe VOD emphasizing the need to replace chemotherapy with less toxic myeloablative agents.The preliminary results obtained after injection of Human T lymphoid progenitors in P1 are encouraging. While deserving confirmation in larger numbers of patients they could represent an important step forward in improving the outcome of haploidentical HSCT for SCID. DisclosuresCavazzana: Smart Immune: Other: co-founder.