History and current status of newborn screening for severe combined immunodeficiency

Quality considerations and major pitfalls for high throughput DNA-based newborn screening for severe combined immunodeficiency and spinal muscular atrophy

BACKGROUND

Many newborn screening programs worldwide have introduced screening for diseases using DNA extracted from dried blood spots (DBS). In Germany, DNA-based assays are currently used to screen for severe combined immunodeficiency (SCID), spinal muscular atrophy (SMA), and sickle cell disease (SCD).

METHODS

This study analysed the impact of pre-analytic DNA carry-over in sample preparation on the outcome of DNA-based newborn screening for SCID and SMA and compared the efficacy of rapid extraction versus automated protocols. Additionally, the distribution of T cell receptor excision circles (TREC) on DBS cards, commonly used for routine newborn screening, was determined.

RESULTS

Contaminations from the punching procedure were detected in the SCID and SMA assays in all experimental setups tested. However, a careful evaluation of a cut-off allowed for a clear separation of true positive polymerase chain reaction (PCR) amplifications. Our rapid in-house extraction protocol produced similar amounts compared to automated commercial systems. Therefore, it can be used for reliable DNA-based screening. Additionally, the amount of extracted DNA significantly differs depending on the location of punching within a DBS.

CONCLUSIONS

Newborn screening for SMA and SCID can be performed reliably. It is crucial to ensure that affected newborns are not overlooked. Therefore a carefully consideration of potential contaminating factors and the definition of appropriate cut-offs to minimise the risk of false results are of special concern. It is also important to note that the location of punching plays a pivotal role, and therefore an exact quantification of TREC numbers per μl may not be reliable and should therefore be avoided.

Serious neurological adverse events in immunocompetent children and adolescents caused by viral reactivation in the years following varicella vaccination

Serious adverse events following vaccination include medical complications that require hospitalisation. The live varicella vaccine that was approved by the Food and Drug Administration in the United States in 1995 has an excellent safety record. Since the vaccine is a live virus, adverse events are more common in immunocompromised children who are vaccinated inadvertently. This review includes only serious adverse events in children considered to be immunocompetent. The serious adverse event called varicella vaccine meningitis was first reported in a hospitalised immunocompetent child in 2008. When we carried out a literature search, we found 15 cases of immunocompetent children and adolescents with varicella vaccine meningitis; the median age was 11 years. Eight of the children had received two varicella vaccinations. Most of the children also had a concomitant herpes zoster rash, although three did not. The children lived in the United States, Greece, Germany, Switzerland, and Japan. During our literature search, we found five additional cases of serious neurological events in immunocompetent children; these included 4 cases of progressive herpes zoster and one case of acute retinitis. Pulses of enteral corticosteroids as well as a lack of herpes simplex virus antibody may be risk factors for reactivation in immunocompetent children. All 20 children with adverse events were treated with acyclovir and recovered; 19 were hospitalised and one child was managed as an outpatient. Even though the number of neurological adverse events remains exceedingly low following varicella vaccination, we recommend documentation of those caused by the vaccine virus.

Two patients with ZAP-70 deficiency in China present with a different genetic, immunological, and clinical phenotype

Zeta(ζ)-Chain Associated Protein Kinase 70 kDa (ZAP-70) deficiency is a rare autosomal recessive primary immunodeficiency disease. Little is known about this disease. In this study, we report two patients to extend the range of clinical phenotypes and immunophenotypes associated with ZAP-70 mutations. We describe the clinical, genetic, and immunological phenotypes of two patients with ZAP-70 deficiency in China, and the data are also compared with the literature. Case 1 presented with leaky severe combined immunodeficiency with low to the absence of CD8 + T cells, while case 2 suffered from a recurrent respiratory infection and had a past medical history of non-EBV-associated Hodgkin's lymphoma. Sequencing revealed novel compound heterozygous mutations in ZAP-70 of these patients. Case 2 is the second ZAP-70 patient presenting a normal CD8 + T cell number. These two cases have been treated with hematopoietic stem cell transplantation. Selective CD8 + T cell loss is an essential feature of the immunophenotype of ZAP-70 deficiency patients, but there are exceptions. Hematopoietic stem cell transplantation can provide excellent long-term immune function and resolution of clinical problems.

Positive Newborn Screening for Severe Combined Immunodeficiency: What Should the Pediatrician Do?

Severe combined immunodeficiency (SCID) is a group of diseases characterized by low T-cell count and impaired T-cell function, resulting in severe cellular and humoral immune defects. If not diagnosed and treated promptly, infants affected by this condition can develop severe infections which will result in death. Delayed treatment can markedly reduce the survival outcome of infants with SCID. T-cell receptor excision circle (TREC) levels are measured on newborn screening to promptly identify infants with SCID. It is important for primary care providers and pediatricians to understand the approach to managing infants with positive TREC-based newborn screening as they may be the first contact for infants with SCID. Primary care providers should be familiar with providing anticipatory guidance to the family in regard to protective isolation, measures to minimize the risk of infection, and the coordination of care with the SCID coordinating center team of specialists. In this article, we use case-based scenarios to review the principles of TREC-based newborn screening, the genetics and subtypes of SCID, and management for an infant with a positive TREC-based newborn screen.

Natural history of infants with non-SCID T cell lymphopenia identified on newborn screen

Newborn screening (NBS) for severe combined immunodeficiency (SCID) can identify infants with non-SCID T cell lymphopenia (TCL). The purpose of this study was to characterize the natural history and genetic findings of infants with non-SCID TCL identified on NBS. We analyzed data from 80 infants with non-SCID TCL in the mid-Atlantic region between 2012 and 2019. 66 patients underwent genetic testing and 41 (51%) had identified genetic variant(s). The most common genetic variants were thymic defects (33%), defects with unknown mechanisms (12%) and bone marrow production defects (5%). The genetic cohort had significantly lower median initial CD3+, CD4+, CD8+ and CD4/CD45RA+ T cell counts compared to the non-genetic cohort. Thirty-six (45%) had either viral, bacterial, or fungal infection; only one patient had an opportunistic infection (vaccine strain VZV infection). Twenty-six (31%) of patients had resolution of TCL during the study period.

Newborn screening for severe combined immunodeficiency: The results of the first pilot TREC and KREC study in Ukraine with involving of 10,350 neonates

Severe combined immunodeficiency (SCID) is a group of inborn errors of immunity (IEI) characterized by severe T- and/or B-lymphopenia. At birth, there are usually no clinical signs of the disease, but in the first year of life, often in the first months the disease manifests with severe infections. Timely diagnosis and treatment play a crucial role in patient survival. In Ukraine, the expansion of hemostatic stem cell transplantation and the development of a registry of bone marrow donors in the last few years have created opportunities for early correction of IEI and improving the quality and life expectancy of children with SCID. For the first time in Ukraine, we initiated a pilot study on newborn screening for severe combined immunodeficiency and T-cell lymphopenia by determining T cell receptor excision circles (TRECs) and kappa-deleting recombination excision circles (KRECs). The analysis of TREC and KREC was performed by real-time polymerase chain reaction (RT-PCR) followed by analysis of melting curves in neonatal dry blood spots (DBS). The DBS samples were collected between May 2020 and January 2022. In total, 10,350 newborns were screened. Sixty-five blood DNA samples were used for control: 25 from patients with ataxia-telangiectasia, 37 - from patients with Nijmegen breakage syndrome, 1 – with X-linked agammaglobulinemia, 2 – with SCID (JAK3 deficiency and DCLRE1C deficiency). Retest from the first DBS was provided in 5.8% of patients. New sample test was needed in 73 (0.7%) of newborns. Referral to confirm or rule out the diagnosis was used in 3 cases, including one urgent abnormal value. CID (T^lowB+NK+) was confirmed in a patient with the urgent abnormal value. The results of a pilot study in Ukraine are compared to other studies (the referral rate 1: 3,450). Approbation of the method on DNA samples of children with ataxia-telangiectasia and Nijmegen syndrome showed a high sensitivity of TRECs (a total of 95.2% with cut-off 2000 copies per 10⁶ cells) for the detection of these diseases. Thus, the tested method has shown its effectiveness for the detection of T- and B-lymphopenia and can be used for implementation of newborn screening for SCID in Ukraine.

SCID and Other Inborn Errors of Immunity with Low TRECs - the Brazilian Experience

Severe combined immunodeficiency, SCID, is a pediatric emergency that represents the most critical group of inborn errors of immunity (IEI). Affected infants present with early onset life-threatening infections due to absent or non-functional T cells. Without early diagnosis and curative treatment, most die in early infancy. As most affected infants appear healthy at birth, newborn screening (NBS) is essential to identify and treat patients before the onset of symptoms. Here, we report 47 Brazilian patients investigated between 2009 and 2020 for SCID due to either a positive family history and/or clinical impression and low TRECs. Based on clinical presentation, laboratory finding, and genetic information, 24 patients were diagnosed as typical SCID, 14 as leaky SCID, and 6 as Omenn syndrome; 2 patients had non-SCID IEI, and 1 remained undefined. Disease onset median age was 2 months, but at the time of diagnosis and treatment, median ages were 6.5 and 11.5 months, respectively, revealing considerable delay which affected negatively treatment success. While overall survival was 51.1%, only 66.7% (30/45) lived long enough to undergo hematopoietic stem-cell transplantation, which was successful in 70% of cases. Forty-three of 47 (91.5%) patients underwent genetic testing, with a 65.1% success rate. Even though our patients did not come from the NBS programs, the diagnosis of SCID improved in Brazil during the pilot programs, likely due to improved medical education. However, we estimate that at least 80% of SCID cases are still missed. NBS-SCID started to be universally implemented in the city of São Paulo in May 2021, and it is our hope that other cities will follow, leading to early diagnosis and higher survival of SCID patients in Brazil.

Inborn Errors of Immunity in the Premature Infant: Challenges in Recognition and Diagnosis

Due to heightened awareness and advanced genetic tools, inborn errors of immunity (IEI) are increasingly recognized in children. However, diagnosing of IEI in premature infants is challenging and, subsequently, reports of IEI in premature infants remain rare. This review focuses on how common disorders of prematurity, such as sepsis, necrotizing enterocolitis, and bronchopulmonary dysplasia, can clinically overlap with presenting signs of IEI. We present four recent cases from a single neonatal intensive care unit that highlight diagnostic dilemmas facing neonatologists and clinical immunologists when considering IEI in preterm infants. Finally, we present a conceptual framework for when to consider IEI in premature infants and a guide to initial workup of premature infants suspected of having IEI.

Implementation of TREC/KREC detection protocol for newborn SCID screening in Bulgaria: a pilot study

Neonatal screening for inborn errors of immunity (IEI), based on quantification of T-cell-receptor- excision circles (TRECs) and kappa-deleting recombination-excision circles (KRECs) from dried blood spots (DBS), allows early diagnosis and improved outcomes for the affected children. Determination of TREC/KREC levels from prospectively collected newborns' Guthrie cards and from DBS samples of patients with confirmed IEI was done using a commercial kit. Retrospective assessment of flow cytometry evaluation of TREC/KREC correspondence with lymphocyte subpopulations and evaluation of the correlations between TREC and KREC with immune cells, based on the data from patients with suspected or confirmed immune disorders, were conducted. 2,228 Guthrie cards were tested, 1276 for TREC only and 952 for both TREC and KREC. Eight newborns (0.36%) were TREC positive and 10 (1.05%) had KREC below the cut-off. The re-testing rate was 1.88%. Retrospective analysis demonstrated that the TREC/KREC assay identifies 100% of severe combined immune deficiencies (SCID) cases when DBS were collected at birth. Correlation analysis showed moderate significant correlations between TREC and the absolute numbers of CD4 cells (r = 0.634, p < 0.01) and total T cells (r = 0.536, p < 0.01). The ability of KREC levels to predict abnormal absolute (AUC of 0.772) and relative (AUC 0.731) levels of B cells was demonstrated.

Severe Combined Immunodeficiency: Knowledge and Information Needs Among Healthcare Providers

BACKGROUND

Severe combined immunodeficiency (SCID) is a group of life-threatening genetic disorders responsible for severe dysfunctions of the immune system. Despite the expansion of newborn screening in the U.S., there are gaps in healthcare providers' knowledge of SCID.

METHODS

We recruited 277 U.S. healthcare providers for an online survey. The survey assessed providers' experience with SCID patients, knowledge about SCID, and needs and preferred formats for SCID-related informational resources. We examined differences between providers who have seen 2 or more patients with SCID (SCID provider group) and those who have seen 0-1 SCID patients (non-SCID provider group).

RESULTS

Overall, 210 (75.8%) providers were included in the non-SCID provider group, and 121 (57.6%) of these providers were pediatricians. Compared to the SCID provider group, non-SCID provider group reported lower mean rating of SCID knowledge (x̄ = 4.8 vs. x̄ = 8.6, p < 0.0001) and higher informational needs. The largest informational needs identified by the non-SCID provider group were "understanding specific type of SCID" and "understanding what to expect across the lifespan." In the SCID provider group, the highest rated informational need was "family support referrals." Participants in the non-SCID provider group identified scientific publications and websites as preferred formats, with some variation between medical specialties.

CONCLUSION

Based on their experience with treating SCID patients, providers have varying levels of SCID knowledge and different informational needs. For providers who have encountered few SCID patients, informational needs start early, usually immediately after receiving a positive newborn screening result. These findings provide useful direction for the development and preferred outlets for receiving SCID-related information, with some variations between different types of providers. Results from this study will serve as a guide for creating relevant and accessible SCID resources for providers who can utilize them to improve care for SCID patients.

Primary immunodeficiency diseases in the newborn

The normal neonate’s immune system is anatomically completed but antigenically inexperienced and shows somewhat decreased role of a number of immunological pathways. Aside from anatomic characteristics (e.g., thin skin and mucosal barriers) of newborn, weakened pro-inflammatory and T-helper cell type 1 cytokine release and lessened cell-mediated immunity predispose the neonate more susceptible to all types of infections. Furthermore, many types of primary immunodeficiency diseases (PIDs) that present in neonatal period are potentially life threatening. However, most of the newborns stand this period without sickness due to complete innate immunity with other adaptive immune system mechanisms and transferred maternal immunoglobulin G. Besides unique immunity of the preterm and normal newborns; risk factors, clinical features, and laboratory evaluation of most common PIDs in newborn are told in this article. The range of PIDs is growing, and the diagnosis and management of these disorders continues to increase in complexity. The most common PID types of the newborn including antibody deficiencies, cellular/combined immunodeficiencies, phagocytic diseases, complement deficiencies, and innate immune system and other disorders are briefly mentioned here as well.

Rotavirus vaccination impact, Ireland, implications for vaccine confidence and screening

BACKGROUND

Rotavirus vaccine efficacy is well established. However, it is important to consistently demonstrate the positive impact of vaccination programmes in order to optimize uptake rates and combat vaccine hesitancy.

METHODS

Routine data were used to examine rotavirus vaccine effectiveness in Ireland, including changes in age-specific crude incidence rates (CIRs), hospitalizations and hospital length of stay. National intussusception incidence was interrogated. Vaccination status of vaccine-eligible cases of rotavirus infection was determined.

RESULTS

Nationally, a reduction in the CIR of rotavirus infection of 77.2% [95% confidence interval (CI) 57.8-88.5%, P<0.001] was observed post-inclusion of the rotavirus vaccine in the primary immunization schedule. A decrease in hospitalizations of 85.5% (95% CI 79.3-90.2%, P<0.001), 86.5% (95% CI 82.9-89.4%, P<0.001) and 78.5% (95% CI 74.7-81.9%, P<0.001) was observed in children aged <1, <2 and <5 years, respectively. Most hospitalizations occurred in infants too young to have been vaccinated. There was no significant difference in median length of stay for children hospitalized with rotavirus infection. Decreased CIRs and hospitalization rates in unvaccinated children aged between 2 and 5 years suggest community immunity. Vaccine non-protection was 0.13%. No increase in the national CIR of intussusception was observed.

CONCLUSIONS

Inclusion of the rotavirus vaccine in the Irish primary immunization schedule has resulted in a significant reduction in the burden of rotavirus infection. However, vaccine hesitancy remains a concern. With new vaccination programmes, risk of vaccine harms should be considered and mitigated in order to protect individuals and the integrity of the programme.

Neonatal Lymphopenia Screening Is Important For Early Diagnosis of Severe Combined Immunodeficiency

OBJECTIVE

 T-cell receptor excision circles are expensive for neonatal severe combined immunodeficiency screening in developing countries. We aimed to detect immunodeficiencies presenting with lymphopenia to enable screening in the general population and to improve awareness regarding lymphopenia among clinicians.

STUDY DESIGN

 This study was conducted prospectively. In all newborns included, complete blood count from umbilical cord blood samples was recorded. Absolute lymphopenia was defined as absolute lymphocyte count <3,000/mm³ in umbilical cord blood sample. Complete blood count was repeated at month 1 in cases found to have lymphopenia.

RESULTS

 Overall, 2,000 newborns were included in the study. Absolute lymphopenia was detected in 42 newborns (2.1%), while lymphocyte count was >3,000/mm³ in 1,958 newborns (97.9%). Two infants with persisted lymphopenia at the end of the first month; therefore, further evaluations such as lymphocyte subsets for severe combined immunodeficiency (SCID) were done. In the first infant, the lymphocyte subgroups were detected as compatible with T (-), B (-), natural killer cells (NK) (+) SCID phenotype RAG defect. Sanger sequencing revealed that NM_000448 c.2209C > T (p.R737C) homozygous mutation of RAG1 gene. In the other infant, the lymphocyte subgroups were found as considered with T (-), B (+) NK (-) SCID phenotype JAK3 defect. Both patients underwent hematopoietic stem cell transplantation from human leukocyte antigen-matched family member.

CONCLUSION

 Absolute lymphopenia by complete blood count is a more simpler, relatively noninvasive and inexpensive screening methodfor detection of SCID in newborns compared with T-cell receptor excision circles technique.

KEY POINTS

· Our study was conducted with a much smaller number of study groups compared with the previous ones.. · However, SCID was found at a higher rate compared with other studies.. · Our study for this disease that is common in our country where consanguineous marriages are common.

Pulmonary Manifestations of Immunodeficiency and Immunosuppressive Diseases Other than Human Immunodeficiency Virus

Immune deficiencies may alter normal lung function and protective mechanisms, resulting in a myriad of pulmonary manifestations. Primary immunodeficiencies involve multiple branches of the immune system, and defects may predispose to recurrent upper and lower respiratory infections by common pathogens; opportunistic infections; and autoimmune, inflammatory, and malignant processes that may result in interstitial pneumonias. Secondary immunodeficiencies may result from neoplasms or their treatment, organ transplant and immunosuppression, and from autoimmune diseases and their treatments. Primary and secondary immunodeficiencies and their pulmonary manifestations may be difficult to diagnose and treat. A multidisciplinary approach to evaluation is essential.

SCID newborn screening: What we've learned

Newborn screening for severe combined immunodeficiency, the most profound form of primary immune system defects, has long been recognized as a measure that would decrease morbidity and improve outcomes by helping patients avoid devastating infections and receive prompt immune-restoring therapy. The T-cell receptor excision circle test, developed in 2005, proved to be successful in pilot studies starting in the period 2008 to 2010, and by 2019 all states in the United States had adopted versions of it in their public health programs. Introduction of newborn screening for severe combined immunodeficiency, the first immune disorder accepted for population-based screening, has drastically changed the presentation of this disorder while providing important lessons for public health programs, immunologists, and transplanters.

Characterization of Infants with Idiopathic Transient and Persistent T Cell Lymphopenia Identified by Newborn Screening-a Single-Center Experience in New York State

PURPOSE

Newborn screening (NBS) quantifies T cell receptor excision circles (TREC) and identifies infants with T cell lymphopenia (TCL). This study elucidates the demographics, laboratory characteristics, genetics, and clinical outcomes following live viral vaccine administration of term infants with transient or persistent idiopathic TCL.

METHODS

A single-center retrospective analysis was performed from September 2010 through June 2018. Laboratory variables were compared with Mann-Whitney tests. Correlations between initial TREC levels and T cell counts were determined by Spearman tests.

RESULTS

Twenty-two transient and 21 persistent TCL infants were identified. Males comprised 68% of the transient and 52% of the persistent TCL cohorts. Whites comprised 23% of the transient and 29% of the persistent cohorts. Median initial TREC levels did not differ (66 vs. 60 TRECs/μL of blood, P = 0.58). The transient cohort had higher median initial CD3⁺ (2135 vs. 1169 cells/μL, P < 0.001), CD4⁺ (1460 vs. 866 cells/μL, P < 0.001), and CD8⁺ (538 vs. 277 cells/μL, P < 0.001) counts. The median age of resolution for the transient cohort was 38 days. Genetic testing revealed 2 genes of interest which warrant further study and several variants of uncertain significance in immunology-related genes in the persistent cohort. 19 transient and 14 persistent subjects received the initial rotavirus and/or MMRV immunization. No adverse reactions to live viral vaccines were reported in either cohort.

CONCLUSION

Transient and persistent TCL infants differ by demographic, laboratory, and clinical characteristics. Select transient and persistent TCL patients may safely receive live attenuated viral vaccines, but larger confirmatory studies are needed.

Newborn Screening for SCID and Other Severe Primary Immunodeficiency in the Polish-German Transborder Area: Experience From the First 14 Months of Collaboration

In 2017, in the Polish-German transborder area of West Pomerania, Mecklenburg-Western Pomerania, and Brandenburg, in collaboration with two centers in Warsaw, a partnership in the field of newborn screening (NBS) for severe primary immunodeficiency diseases (PID), mainly severe combined immunodeficiency (SCID), was initiated. SCID, but also some other severe PID, is a group of disorders characterized by the absence of T and/or B and NK cells. Affected infants are susceptible to life-threatening infections, but early detection gives a chance for effective treatment. The prevalence of SCID in the Polish and German populations is unknown but can be comparable to other countries (1:50,000–100,000). SCID NBS tests are based on real-time polymerase chain reaction (qPCR) and the measurement of a number of T cell receptor excision circles (TREC), kappa-deleting recombination excision circles (KREC), and beta-actin (ACTB) as a quality marker of DNA. This method can also be effective in NBS for other severe PID with T- and/or B-cell lymphopenia, including combined immunodeficiency (CID) or agammaglobulinemia. During the 14 months of collaboration, 44,287 newborns were screened according to the ImmunoIVD protocol. Within 65 positive samples, seven were classified to immediate recall and 58 requested a second sample. Examination of the 58 second samples resulted in recalling one newborn. Confirmatory tests included immunophenotyping of lymphocyte subsets with extension to TCR repertoire, lymphoproliferation tests, radiosensitivity tests, maternal engraftment assays, and molecular tests. Final diagnosis included: one case of T-B^lowNK+ SCID, one case of atypical T^low B^lowNK+ CID, one case of autosomal recessive agammaglobulinemia, and one case of Nijmegen breakage syndrome. Among four other positive results, three infants presented with T- and/or B-cell lymphopenia due to either the mother's immunosuppression, prematurity, or unknown reasons, which resolved or almost normalized in the first months of life. One newborn was classified as truly false positive. The overall positive predictive value (PPV) for the diagnosis of severe PID was 50.0%. This is the first population screening study that allowed identification of newborns with T and/or B immunodeficiency in Central and Eastern Europe.

Nonsevere combined immunodeficiency T-cell lymphopenia identified through newborn screening

PURPOSE OF REVIEW

Although severe combined immunodeficiency (SCID) is the primary target condition for newborn screening (NBS), over 25 secondary targets, conditions other than SCID, have been identified. There is no standard method for evaluating neonates with non-SCID T-cell lymphopenia (TCL) and no standard approaches to treatment. We will describe these conditions and discuss recommendations for evaluating and follow-up of non-SCID TCL detected by NBS.

RECENT FINDINGS

The birth prevalence of non-SCID TCL detected through SCID NBS is higher than SCID and can be a burden on NBS programs. We will present some publications discussing outcomes and comorbidities in these patients.

SUMMARY

NBS for SCID has been very successful in identifying infants with SCID at birth to institute early life saving therapies. TCL due to other conditions can cause significant immune deficiency and treatment is dependent on the cause of the defect, as well as the magnitude of the immunodeficiency. Data collection from NBS programs should include assessment of various therapies and clinical outcomes. Better systems for recording long-term outcomes of SCID NBS including both SCID and non-SCID conditions should become a priority for NBS programs. This will help to advance the goal of NBS programs: improve outcomes in the most cost-effective manner.

Second-Tier Next Generation Sequencing Integrated in Nationwide Newborn Screening Provides Rapid Molecular Diagnostics of Severe Combined Immunodeficiency

Severe combined immunodeficiency (SCID) and other T cell lymphopenias can be detected during newborn screening (NBS) by measuring T cell receptor excision circles (TRECs) in dried blood spot (DBS) DNA. Second tier next generation sequencing (NGS) with an amplicon based targeted gene panel using the same DBS DNA was introduced as part of our prospective pilot research project in 2015. With written parental consent, 21 000 newborns were TREC-tested in the pilot. Three newborns were identified with SCID, and disease-causing variants in IL2RG, RAG2, and RMRP were confirmed by NGS on the initial DBS DNA. The molecular findings directed follow-up and therapy: the IL2RG-SCID underwent early hematopoietic stem cell transplantation (HSCT) without any complications; the leaky RAG2-SCID received prophylactic antibiotics, antifungals, and immunoglobulin infusions, and underwent HSCT at 1 year of age. The child with RMRP-SCID had complete Hirschsprung disease and died at 1 month of age. Since January 2018, all newborns in Norway have been offered NBS for SCID using 1st tier TRECs and 2nd tier gene panel NGS on DBS DNA. During the first 20 months of nationwide SCID screening an additional 88 000 newborns were TREC tested, and four new SCID cases were identified. Disease-causing variants in DCLRE1C, JAK3, NBN, and IL2RG were molecularly confirmed on day 8, 15, 8 and 6, respectively after birth, using the initial NBS blood spot. Targeted gene panel NGS integrated into the NBS algorithm rapidly delineated the specific molecular diagnoses and provided information useful for management, targeted therapy and follow-up i.e., X rays and CT scans were avoided in the radiosensitive SCID. Second tier targeted NGS on the same DBS DNA as the TREC test provided instant confirmation or exclusion of SCID, and made it possible to use a less stringent TREC cut-off value. This allowed for the detection of leaky SCIDs, and simultaneously reduced the number of control samples, recalls and false positives. Mothers were instructed to stop breastfeeding until maternal cytomegalovirus (CMV) status was determined. Our limited data suggest that shorter time-interval from birth to intervention, may prevent breast milk transmitted CMV infection in classical SCID.

Severe Combined Immunodeficiency: A Review for Neonatal Clinicians

The proper development and function of T cells is imperative in the creation of adequate cell-mediated and humoral immunity. Healthy term newborns have baseline immune immaturity, increasing their risk of infections, but significant immunologic consequences can occur, because of abnormal T-cell maturation. Combined immunodeficiencies can result, because B cells and natural killer cells rely on successful interactions with T cells to ensure their proper performance and survival. Severe combined immunodeficiency (SCID) is the most noteworthy of these conditions, leading to considerable early morbidity and often death by the age of 1 year if left untreated. Newborn screening for SCID is effective and allows for early implementation of lifesaving supportive measures, including protective isolation, initiation of prophylactic antimicrobials, caution with blood product transfusions, and avoidance of live vaccinations. Once a definitive diagnosis of SCID has been established, treatment frequently involves bone marrow or stem cell transplantation; however, enzyme replacement and gene therapy are also becoming options in those with SCID due to adenosine deaminase deficiency and other forms of SCID. Neonatal clinicians should understand the screening and diagnostic approach to SCID along with the initial management approaches for these extremely high-risk patients.

Clinical, Immunological, and Genetic Features in 49 Patients With ZAP-70 Deficiency: A Systematic Review

Background: Zeta-Chain Associated Protein Kinase 70 kDa (ZAP-70) deficiency is a rare combined immunodeficiency (CID) caused by recessive homozygous/compound heterozygous loss-of-function mutations in the ZAP70 gene. Patients with ZAP-70 deficiency present with a variety of clinical manifestations, particularly recurrent respiratory infections and cutaneous involvements. Therefore, a systematic review of ZAP-70 deficiency is helpful to achieve a comprehensive view of this disease.

Methods: We searched PubMed, Web of Science, and Scopus databases for all reported ZAP-70 deficient patients and screened against the described eligibility criteria. A total of 49 ZAP-70 deficient patients were identified from 33 articles. For all patients, demographic, clinical, immunologic, and molecular data were collected.

Results: ZAP-70 deficient patients have been reported in the literature with a broad spectrum of clinical manifestations including recurrent respiratory infections (81.8%), cutaneous involvement (57.9%), lymphoproliferation (32.4%), autoimmunity (19.4%), enteropathy (18.4%), and increased risk of malignancies (8.1%). The predominant immunologic phenotype was low CD8+ T cell counts (97.9%). Immunologic profiling showed defective antibody production (57%) and decreased lymphocyte responses to mitogenic stimuli such as phytohemagglutinin (PHA) (95%). Mutations of the ZAP70 gene were located throughout the gene, and there was no mutational hotspot. However, most of the mutations were located in the kinase domain. Hematopoietic stem cell transplantation (HSCT) was applied as the major curative treatment in 25 (51%) of the patients, 18 patients survived transplantation, while two patients died and three required a second transplant in order to achieve full remission.

Conclusion: Newborns with consanguineous parents, positive family history of CID, and low CD8+ T cell counts should be considered for ZAP-70 deficiency screening, since early diagnosis and treatment with HSCT can lead to a more favorable outcome. Based on the current evidence, there is no genotype-phenotype correlation in ZAP-70 deficient patients.

Spinal Muscular Atrophy: Past, Present, and Future

Spinal muscular atrophy (SMA) is an autosomal recessive neuromuscular disease caused by deletions or mutations in the survival motor neuron (SMN1) gene. SMA is characterized by loss of lower motor neurons (anterior horn cells) in the spinal cord and brainstem nuclei, leading to progressive symmetrical muscle weakness and atrophy. It affects approximately 1 in 6,000 to 1 in 10,000 individuals and is the most common inherited cause of childhood mortality, but this may soon change given recent developments. In December 2016, nusinersen, an antisense oligonucleotide drug, was approved by the United States Food and Drug Administration for the treatment of SMA, and in July 2018, SMA was added to the recommended uniform screening panel, a list of conditions that all states are encouraged to include in their newborn screening (NBS) panels. In this review, we begin with a brief clinical history of the diagnosis of SMA, discuss the current SMA clinical classification system, describe the current treatment, and discuss evolving treatment guidelines. We then discuss the path to include SMA in NBS programs as well as the controversies it engenders because the variability in age at symptom onset means early identification of asymptomatic patients who will not require therapy for years or decades. We also consider alternate population screening opportunities. Next, we consider experimental treatments. We conclude by supporting NBS for SMA with the caveat that a long-term follow-up registry is ethically essential to ensure that the benefits outweigh the harms for all screened infants, including those with milder and/or later-onset forms of SMA.

Primary Immunodeficiency in the NICU

Primary immunodeficiency disorders (PIDs) are genetic diseases that lead to increased susceptibility to infection. Hundreds of PIDs have now been described, but a select subset commonly presents in the neonatal period. Neonates, especially premature newborns, have relative immune immaturity that makes it challenging to differentiate PIDs from intrinsic immaturity. Nonetheless, early identification and appropriate management of PIDs are critical, and the neonatal clinician should be familiar with a range of PIDs and their presentations. The neonatal clinician should also be aware of the importance of consulting with an immunologist when a PID is suspected. The role of newborn screening for severe combined immunodeficiency, as well as the initial steps of laboratory evaluation for a PID should be familiar to those caring for neonates. Finally, it is important for providers to be familiar with the initial management steps that can be taken to reduce the risk of infection in affected patients.

Abnormal Newborn Screening Follow-up for Severe Combined Immunodeficiency in an Amish Cohort with Cartilage-Hair Hypoplasia

Cartilage-hair hypoplasia (CHH) is an autosomal recessive, short limb skeletal dysplasia with a variable immunologic phenotype. The spectrum of immune function ranges from clinically normal to severe combined immunodeficiency (SCID). Multiple studies have shown that abnormal immune parameters may not predict severe outcomes. Newborn screening (NBS) using T cell receptor excision circle (TREC) assay can now effectively identify infants with severe T cell deficiency who are at risk for SCID. NBS has allowed for cost-effective identification of patients with SCID and improved outcomes with hematopoietic stem cell transplant (HSCT). Ohio reports two abnormal TREC results: decreased and absent TREC. This study evaluated the laboratory and clinical differences in eight Amish patients with CHH with an abnormal TREC result on the NBS. There were four patients with absent TREC and four patients with decreased TREC. The absent TREC patients had lower CD3, CD4, naïve CD4, CD8 cells, and phytohemagglutinin (PHA)-induced lymphocyte proliferation. Three patients with absent TREC were diagnosed with SCID and two underwent successful HSCT. Patients with absent TREC experienced more CHH-related morbidity including anemia requiring transfusion, Hirschsprung's disease, and failure to thrive. No patients with decreased TREC required HSCT. Our study indicates that CHH patients with absent TREC tend to have more severe immunological and clinical phenotype than patients with decreased TREC. Confirmation of these trends in a larger group would guide providers and parents in a timely referral for HSCT, or cost-effective surveillance monitoring of children with a life-threatening illness.

Early diagnosis of ataxia telangiectasia in the neonatal phase: a parents' perspective

Ataxia telangiectasia (A-T) is a severe neurodegenerative disorder with variable immunodeficiency. Together with the Dutch A-T community, we investigated the opinion of A-T parents on an early A-T diagnosis in the asymptomatic phase of the disease. During an annual national meeting for A-T patients and families, the topic of an early A-T diagnosis was discussed in relation to the recent introduction of neonatal screening for severe combined immunodeficiency (SCID) in the Netherlands. Based on the discussion, individual arguments were identified and processed into a questionnaire, which was sent out to 64 A-T parents (32 families). Arguments included were insecurity to diagnosis, possible medical advantages, appropriate genetic counseling and family planning, loss of "golden" year(s), and early cancer screening for parents. The response rate was 55% (n = 35 parents). Twenty-six (74%) parents felt that the advantages of an early diagnosis outweighed the disadvantages, five parents thought that the disadvantages would outweigh the advantages (14%), and four parents did not indicate a preference.Conclusion: The majority of parents of a child with A-T would have preferred an early diagnosis during the asymptomatic phase of the disease, because the uncertainty during the diagnostic process had had a major impact on their lives. In addition, the knowledge of being carriers of an ATM gene mutation influenced decisions about family planning. Parents who opposed against an early diagnosis emphasized the joy of having a seemingly healthy child until diagnosis.What is Known:• Ataxia telangiectasia (A-T) is a devastating DNA repair disorder with a huge impact on quality of life of patients and their parents.• Patients with A-T may incidentally be identified at birth as the consequence of neonatal screening for severe combined immunodeficiency (SCID).What is New:• The majority of Dutch parents of A-T patients (74%) would have preferred an early diagnosis of their child in the asymptomatic phase of the disease.• Major arguments for an early A-T diagnosis were (1) the experienced insecurity in diagnostic trajectories and its impact on families and (2) the knowledge of being ATM mutation carriers when deciding about family planning. An argument against an early diagnosis is losing the joy of having a seemingly healthy child until diagnosis.

Ataxia Telangiectasia Diagnosed on Newborn Screening-Case Cohort of 5 Years' Experience

Ataxia telangiectasia (AT) is a genetic condition caused by mutations involving ATM (Ataxia Telangiectasia Mutated). This gene is responsible for the expression of a DNA double stranded break repair kinase, the ATM protein kinase. The syndrome encompasses combined immunodeficiency and various degrees of neurological abnormalities and increased risk of malignancy. Typically, patients present early in life with delay in neurological milestones, but very infrequently, with life threatening infections typical of a profound T cell deficiency. It would therefore be unexpected to identify this condition immediately after birth using T cell receptor excision circle (TREC)-based newborn screening (NBS) for SCID. We sought to evaluate the frequency of AT detected by NBS, and to assess immunity as well as the genetic aberrations associated with this early presentation. Here, we describe the clinical, laboratory, and genetic features of patients diagnosed with AT through the Ontario NBS program for SCID, and followed in our center since its inception in 2013. Four patients were diagnosed with AT as a result of low TRECs on NBS. In each case, whole exome sequencing was diagnostic. All of our patients had compound heterozygous mutations involving the FRAP-ATM-TRRAP (FAT) domain of the ATM gene, which appears critical for kinase activity and is highly sensitive to mutagenesis. Our patients presented with profound lymphopenia involving both B and T cells. The ratio of naïve/memory CD45+RA/RO T cells population was variable. T cell repertoire showed decreased T cell diversity. Two out of four patients had decreased specific antibody response to vaccination and hypogammaglobulinemia requiring IVIG replacement. In two patients, profound decreased responses to phytohemagglutinin stimulation was observed. In the other two patients, the initial robust response declined with time. In summary, the rate of detection of AT through NBS had been surprisingly high at our center. One case was identified per year, while the total rate for SCID has been five new cases per year. This early detection may allow for better prospective evaluation of AT shortly after birth, and may assist in formulating early and more effective interventions both for the neurological as well as the immune abnormalities in this syndrome.

Fifteen-minute consultation: Recognising primary immune deficiencies in children

Children with primary immunodeficiency syndromes present with broad variation of clinical features and the consequences are often severe if not promptly recognised. Here, support is provided for the general paediatrician to recognise primary immunodeficiencies among the many children they meet in their clinical practice.

Latin American consensus on the supportive management of patients with severe combined immunodeficiency

Severe combined immunodeficiency (SCID) represents the most lethal form of primary immunodeficiency, with mortality rates of greater than 90% within the first year of life without treatment. Hematopoietic stem cell transplantation and gene therapy are the only curative treatments available, and the best-known prognostic factors for success are age at diagnosis, age at hematopoietic stem cell transplantation, and the comorbidities that develop in between. There are no evidence-based guidelines for standardized clinical care for patients with SCID during the time between diagnosis and definitive treatment, and we aim to generate a consensus management strategy on the supportive care of patients with SCID. First, we gathered available information about SCID diagnostic and therapeutic guidelines, then we developed a document including diagnostic and therapeutic interventions, and finally we submitted the interventions for expert consensus through a modified Delphi technique. Interventions are grouped in 10 topic domains, including 123 "agreed" and 38 "nonagreed" statements. This document intends to standardize supportive clinical care of patients with SCID from diagnosis to definitive treatment, reduce disease burden, and ultimately improve prognosis, particularly in countries where newborn screening for SCID is not universally available and delayed diagnosis is the rule. Our work intends to provide a tool not only for immunologists but also for primary care physicians and other specialists involved in the care of patients with SCID.

[Advances in newborn screening and immune system reconstitution of severe combined immunodeficiency]

Severe combined immunodeficiency disease (SCID) is a group of rare congenital diseases characterized by severe deficiencies in T lymphocyte counts and/or function. The recurrent, persistent and severe infections are its clinical manifestations. Neonatal screening and immune system reconstruction would improve the prognosis of SCID children. Newborn screening programs based on T-cell receptor excision circles (TRECs) quantitative detection have been carried out in clinical practice, however, the methods still have some limitations. Other new methods such as mass spectrometry and T lymphocyte-specific biomarker assays are still under investigation. Hematopoietic stem cell transplantation and gene therapy are the two main methods for reconstructing immune function in SCID children. Through improving the success rate of transplantation and the long-term safety and stability of viral vectors, some achievements have been made by many centers already. However, large-scale prospective studies are needed for evaluation of the long-term efficacy. In this article, the recent progress in newborn screening and immune reconstitution of SCID is reviewed.

Co-appearance of OPV and BCG vaccine-derived complications in two infants with severe combined immunodeficiency

Infants with severe combined immunodeficiency (SCID) are at risk of developing severe life-threatening infections if they are inadvertently given attenuated live vaccines. Concomitant appearance of two live vaccine-associated complications in one person is rarely reported. In this study, we present two SCID infants, who received BCG and oral polio vaccines according to their local immunization schedule early in life, before the diagnosis of immunodeficiency was made. Their clinical presentation, extensive immunological workup, genetic tests, and clinical disease course are presented. Both patients developed localized and disseminated infections originating from the BCG vaccine (BCGitis and BCGiosis, respectively) and in addition suffered from diarrhea and chronic fecal secretion of vaccine-derived poliovirus. Alarmingly, in case 2, the poliovirus was a type 2 vaccine-derived poliovirus in which both neurovirulence attenuation sites reverted to the neurovirulent genotype. These cases highlight the importance of early recognition of SCID by neonatal screening or thorough family anamnesis, and the need to further defer the timing of administration of attenuated live vaccines.

The European Society for Immunodeficiencies (ESID) Registry Working Definitions for the Clinical Diagnosis of Inborn Errors of Immunity

Patient registries are instrumental for clinical research in rare diseases. They help to achieve a sufficient sample size for epidemiological and clinical research and to assess the feasibility of clinical trials. The European Society for Immunodeficiencies (ESID) registry currently comprises information on more than 25,000 patients with inborn errors of immunity (IEI). The prerequisite of a patient to be included into the ESID registry is an IEI either defined by a defect in a gene included in the disease classification of the international union of immunological societies, or verified by applying clinical criteria. Because a relevant number of patients, including those with common variable immunodeficiency (CVID), representing the largest group of patients in the registry, remain without a genetic diagnosis, consensus on classification of these patients is mandatory. Here, we present clinical criteria for a large number of IEI that were designed in expert panels with an external review. They were implemented for novel entries and verification of existing data sets from 2014, yielding a substantial refinement. For instance, 8% of adults and 27% of children with CVID (176 of 1704 patients) were reclassified to 22 different immunodeficiencies, illustrating progress in genetics, but also the previous lack of standardized disease definitions. Importantly, apart from registry purposes, the clinical criteria are also helpful to support treatment decisions in the absence of a genetic diagnosis or in patients with variants of unknown significance.

Newborn Screening for Severe Combined Immunodeficiency and T-cell Lymphopenia in California, 2010-2017

OBJECTIVES

Newborn screening for severe combined immunodeficiency (SCID) was instituted in California in 2010. In the ensuing 6.5 years, 3 252 156 infants in the state had DNA from dried blood spots assayed for T-cell receptor excision circles (TRECs). Abnormal TREC results were followed-up with liquid blood testing for T-cell abnormalities. We report the performance of the SCID screening program and the outcomes of infants who were identified.

METHODS

Data that were reviewed and analyzed included demographics, nursery summaries, TREC and lymphocyte flow-cytometry values, and available follow-up, including clinical and genetic diagnoses, treatments, and outcomes.

RESULTS

Infants with clinically significant T-cell lymphopenia (TCL) were successfully identified at a rate of 1 in 15 300 births. Of these, 50 cases of SCID, or 1 in 65 000 births (95% confidence interval 1 in 51 000-1 in 90 000) were found. Prompt treatment led to 94% survival. Infants with non-SCID TCL were also identified, diagnosed and managed, including 4 with complete DiGeorge syndrome who received thymus transplants. Although no cases of typical SCID are known to have been missed, 2 infants with delayed-onset leaky SCID had normal neonatal TREC screens but came to clinical attention at 7 and 23 months of age.

CONCLUSIONS

Population-based TREC testing, although unable to detect immune defects in which T cells are present at birth, is effective for identifying SCID and clinically important TCL with high sensitivity and specificity. The experience in California supports the rapid, widespread adoption of SCID newborn screening.

Newborn screening for severe combined immunodeficiency and T-cell lymphopenia

The development of a T cell receptor excision circle (TREC) assay utilizing dried blood spots (DBS) made possible universal newborn screening (NBS) for severe combined immunodeficiency (SCID) as a public health measure. Upon being flagged by an abnormal screening test in a SCID screening program, an infant can receive further diagnostic testing for SCID in the neonatal period, prior to onset of infectious complications, to permit immediate institution of protective measures and definitive, life-saving treatment to establish a functional immune system. SCID screening is now the accepted standard of care in state public health departments across the United States, and it is being adopted in many countries. It has proven effective, with infants having this otherwise inapparent but serious, rare disorder achieving survival and immune reconstitution. In addition to bringing to attention infants with the primary screening target diseases, typical SCID and leaky SCID (due to hypomorphic mutations in known SCID genes), the NBS assay for insufficient TRECs in DBS also reveals infants with non-SCID T lymphopenic conditions. Experience has accumulated regarding the range and limitations of diagnoses of newborns with low TRECs and low T cells. Previously unknown immune defects have been discovered, as well as conditions not formerly recognized to have low T cells in the neonatal period.

Analysis of Inflammatory Mediators in Newborn Dried Blood Spot Samples by Chip-Based Immunoaffinity Capillary Electrophoresis

A chip-based immunoaffinity capillary electrophoresis (ICE) system has been developed for measuring inflammatory mediators in dried blood samples routinely taken from newborn babies. A defined area of each dried blood spot was removed from the sample card and its contents eluted. The recovered eluates were injected into the chip and the analytes of interest isolated by the immunoaffinity disk within the chip. The captured analytes were labeled in-situ with a red light-emitting laser dye and electro-eluted into the chip separation channel. Electrophoretic separation of all of the analytes was achieved within 2.0 min with quantification of each peak being performed by online LIF detection and integration of each peak area. The degree of accuracy and precision achieved by the chip-based system is comparable to conventional immunoassays and the system is robust enough to be applied to the analysis of clinical samples.

The Phenotype and Treatment of WIP Deficiency: Literature Synopsis and Review of a Patient With Pre-transplant Serial Donor Lymphocyte Infusions to Eliminate CMV

Early diagnosis of primary immunodeficiency disorders (PID) is vital and allows directed treatment, especially in syndromes with severe or profound combined immunodeficiency. In PID patients with perinatal CMV or other opportunistic, invasive infections (e.g., Pneumocystis or Aspergillus), multi-organ morbidity may already arise within the first months of life, before hematopoietic stem cell transplantation (HSCT) or gene therapy can be undertaken, compromising the definitive treatment and outcome. Deficiency of Wiskott-Aldrich syndrome (WAS) protein-interacting protein (WIP deficiency) causes an autosomal recessive, WAS-like syndrome with early-onset combined immunodeficiency that has been described in three pedigrees to date. While WAS typically includes combined immunodeficiency, microthrombocytopenia, and eczema, the clinical and laboratory phenotypes of WIP-deficient patients-including lymphocyte subsets, platelets, lymphocyte proliferation in vitro, and IgE-varied widely and did not entirely recapitulate WAS, impeding early diagnosis in the reported patients. To elucidate the phenotype of WIP deficiency, we provide a comprehensive synopsis of clinical and laboratory features of all hitherto-described patients (n = 6) and WIP negative mice. Furthermore, we summarize the treatment modalities and outcomes of these patients and review in detail the course of one of them who was successfully treated with serial, unconditioned, maternal, HLA-identical donor lymphocyte infusions (DLI) against life-threatening, invasive CMV infection, followed by a TCRαβ/CD19-depleted, treosulfan/melphalan-conditioned, peripheral blood HSCT and repetitive, secondary-prophylactic, CMV-specific DLI with 1-year post-HSCT follow-up. This strategy could be useful in other patients with substantial premorbidity, considered "too bad to transplant," who have an HLA-identical family donor, to eliminate infections and bridge until definitive treatment.

Psychosocial services for primary immunodeficiency disorder families during hematopoietic cell transplantation: A descriptive study

OBJECTIVE

Caregivers for patients undergoing hematopoietic cell transplantation (HCT) are susceptible to significant psychosocial distress. This cross-sectional study aimed to describe psychosocial support services offered and used by caregivers of pediatric primary immune deficiency (PID) during HCT at 35 hospitals across North America.

METHOD

Caregivers of pediatric patients with PID were recruited by e-mail to participate in an anonymous 140-question survey instrument between April and May 2016 (N = 171).

RESULT

Of those meeting inclusion criteria (53%), family counseling services were only offered to fewer than half of caregivers (42%). Of the survey participants not offered counseling services, the majority desired family counseling (70%) and sibling counseling (73%). That said, when offered counseling, utilization rates were low, with 22% of caregivers using family counseling and none using sibling counseling.

SIGNIFICANCE OF RESULTS

These results indicate the need to offer and tailor counseling services for families throughout the HCT process. Further research should focus on reducing barriers to utilization of counseling services such as offering bedside counseling services, online modalities, and/or financial assistance.

Primary immunodeficiency

Primary immunodeficiency disorder (PID) refers to a large heterogeneous group of disorders that result from defects in immune system development and/or function. PIDs are broadly classified as disorders of adaptive immunity (i.e., T cell, B-cell or combined immunodeficiencies) or of innate immunity (e.g., phagocyte and complement disorders). Although the clinical manifestations of PIDs are highly variable, many disorders involve an increased susceptibility to infection. Early consultation with a clinical immunologist is essential, as timely diagnosis and treatment are imperative for preventing significant disease-associated morbidity. PIDs should be suspected in patients with: recurrent sinus or ear infections or pneumonias within a 1 year period; failure to thrive; poor response to prolonged use of antibiotics; persistent thrush or skin abscesses; or a family history of PID. Patients with multiple autoimmune diseases should also be evaluated. Diagnostic testing often involves lymphocyte proliferation assays, flow cytometry, measurement of serum immunoglobulin (Ig) levels, assessment of serum specific antibody titers in response to vaccine antigens, neutrophil function assays, stimulation assays for cytokine responses, and complement studies. The treatment of PIDs is complex and generally requires both supportive and definitive strategies. Ig replacement therapy is the mainstay of therapy for B-cell disorders, and is also an important supportive treatment for many patients with combined immunodeficiency disorders. The disorders affecting the activity of the T-cell arm of the adaptive system, such as severe combined immunodeficiency, require immune reconstitution as soon as possible. The treatment of innate immunodeficiency disorders varies depending on the type of defect, but may involve antifungal and antibiotic prophylaxis, cytokine replacement, vaccinations and bone marrow transplantation. This article provides an overview of the major categories of PIDs and strategies for the appropriate diagnosis and management of these rare disorders.

NEWBORN SCREENING FOR SEVERE COMBINED IMMUNODEFICIENCIES USING TRECS AND KRECS: SECOND PILOT STUDY IN BRAZIL

OBJECTIVE

To validate the quantification of T-cell receptor excision circles (TRECs) and kappa-deleting recombination excision circles (KRECs) by real-time polymerase chain reaction (qRT-PCR) for newborn screening of primary immunodeficiencies with defects in T and/or B cells in Brazil.

METHODS

Blood samples from newborns and controls were collected on filter paper. DNA was extracted and TRECs, and KRECs were quantified by a duplex real-time PCR. The cutoff values were determined by receiver operating characteristic curve analysis using SPSS software (IBM®, Armonk, NY, USA).

RESULTS

Around 6,881 samples from newborns were collected and TRECs and KRECs were quantified. The TRECs values ranged between 1 and 1,006 TRECs/µL, with mean and median of 160 and 139 TRECs/µL, respectively. Three samples from patients with severe combined immunodeficiency (SCID) showed TRECs below 4/µL and a patient with DiGeorge syndrome showed undetectable TRECs. KRECs values ranged from 10 to 1,097 KRECs/µL, with mean and median of 130 and 108 KRECs/µL. Four patients with agammaglobulinemia had results below 4 KRECs/µL. The cutoff values were 15 TRECs/µL and 14 KRECs/µL and were established according to the receiver operating characteristic curve analysis, with 100% sensitivity for SCID and agammaglobulinemia detection, respectively.

CONCLUSIONS

Quantification of TRECs and KRECs was able to diagnose children with T- and/or B-cell lymphopenia in our study, which validated the technique in Brazil and enabled us to implement the newborn screening program for SCID and agammaglobulinemia.

High Incidence of Severe Combined Immunodeficiency Disease in Saudi Arabia Detected Through Combined T Cell Receptor Excision Circle and Next Generation Sequencing of Newborn Dried Blood Spots

Severe combined immunodeficiency disease (SCID) is the most severe form of primary immunodeficiency disorders (PID). T-cell receptor excision circle (TREC) copy number analysis is an efficient tool for population-based newborn screening (NBS) for SCID and other T cell lymphopenias. We sought to assess the incidence of SCID among Saudi newborn population and examine the feasibility of using targeted next generation sequencing PID gene panel (T-NGS PID) on DNA isolated from dried blood spots (DBSs) in routine NBS programs as a mutation screening tool for samples with low TREC count. Punches from 8,718 DBS collected on Guthrie cards were processed anonymously for the TREC assay. DNA was extracted from samples with confirmed low TREC count, then screened for 22q11.2 deletion syndrome by real-time polymerase chain reaction and for mutations in PID-related genes by T-NGS PID panel. Detected mutations were confirmed by Sanger sequencing. Sixteen out of the 8,718 samples were confirmed to have low TREC copy number. Autosomal recessive mutations in AK2, JAK3, and MTHFD1 were confirmed in three samples. Two additional samples were positive for the 22q11.2 deletion syndrome. In this study, we provide evidence for high incidence of SCID among Saudi population (1/2,906 live births) and demonstrate the feasibility of using T-NGS PID panel on DNA extracted from DBSs as a new reliable, rapid, and cost-effective mutation screening method for newborns with low TREC assay, which can be implemented as part of NBS programs for SCID.

Newborn screening for severe combined immunodeficiency: Evaluation of a commercial T-cell receptor excision circle-based method in Victorian dried blood spots

AIM

Severe combined immunodeficiency (SCID) is the most severe form of primary immunodeficiency and is fatal in infancy if untreated. As early diagnosis is associated with improved outcomes, SCID is an ideal condition to consider for inclusion in a newborn screening (NBS) programme in Australia. In this feasibility study, we evaluated the EnLite Neonatal TREC kit for detection of T-cell receptor excision circles (TRECs) from NBS dried blood spots for the identification of known SCID patients in Victoria.

METHODS

TREC copies/μL were measured retrospectively in 14 children diagnosed with SCID or complete DiGeorge syndrome (CDGS) from 2005 to 2015 at the Royal Children's Hospital, Melbourne. In addition, TREC copies/μL were measured for 501 prospective de-identified NBS cards.

RESULTS

Of 14 known SCID or CDGS samples, 11 were correctly identified as presumptive positive samples with low or undetectable TREC on duplicate testing. The remaining three samples also had low or undetectable TREC on duplicate testing but were considered invalid due to insufficient β-actin DNA amplification. Of the 501 prospective NBS samples, none were identified as presumptive positive samples on duplicate testing.

CONCLUSIONS

The EnLite Neonatal TREC kit correctly identified known SCID or CDGS patients as presumptive positive samples, and initial cut-offs for TREC and β-actin in the Victorian NBS population were determined. A larger pilot study is required to confirm these proposed cut-offs and to evaluate the cost and implementation of this screening programme in Victoria, Australia. Overall, this study provides preliminary data to support the introduction of this assay to the NBS programme in Victoria.

First Year of Israeli Newborn Screening for Severe Combined Immunodeficiency-Clinical Achievements and Insights

Severe combined immunodeficiency (SCID), the most severe form of T cell immunodeficiency, is detectable through quantification of T cell receptor excision circles (TRECs) in dried blood spots obtained at birth. Herein, we describe the results of the first year of the Israeli SCID newborn screening (NBS) program. This important, life-saving screening test is available at no cost for every newborn in Israel. Eight SCID patients were diagnosed through the NBS program in its first year, revealing an incidence of 1:22,500 births in the Israeli population. Consanguine marriages and Muslim ethnic origin were found to be a risk factor in affected newborns, and a founder effect was detected for both IL7Rα and DCLRE1C deficiency SCID. Lymphocyte subset analysis and TREC quantification in the peripheral blood appear to be sufficient for confirmation of typical and leaky SCID and ruling out false positive (FP) results. Detection of secondary targets (infants with non-SCID lymphopenia) did not significantly affect the management or outcomes of these infants in our cohort. In the general, non-immunodeficient population, TREC rises along with gestational age and birth weight, and is significantly higher in females and the firstborn of twin pairs. Low TREC correlates with both gestational age and birth weight in extremely premature newborns. Additionally, the rate of TREC increase per week consistently accelerates with gestational age. Together, these findings mandate a lower cutoff or a more lenient screening algorithm for extremely premature infants, in order to reduce the high rate of FPs within this group. A significant surge in TREC values was observed between 28 and 30 weeks of gestation, where median TREC copy numbers rise by 50% over 2 weeks. These findings suggest a maturational step in T cell development around week 29 gestation, and imply moderate to late preterms should be screened with the same cutoff as term infants. The SCID NBS program is still in its infancy, but is already bearing fruit in the early detection and improved outcomes of children with SCID in Israel and other countries.

Long term outcomes of severe combined immunodeficiency: therapy implications

INTRODUCTION

Newborn screening has led to a better understanding of the prevalence of Severe Combined Immunodeficiency (SCID) overall and in terms of specific genotypes. Survival has improved following hematopoietic stem cell transplantation (HCT) with the best outcomes seen following use of a matched sibling donor. However, questions remain regarding the optimal alternative donor source, appropriate use of conditioning and the impact of these decisions on immune reconstitution and other late morbidities. Areas covered: The currently available literature reporting late effects after HCT for SCID and use of alternative therapies including enzyme replacement, alternative donors and gene therapy are reviewed. A literature search was performed on Pubmed and ClinicalTrials.gov using key words 'Severe Combined Immunodeficiency', 'SCID', 'hematopoietic stem cell transplant', 'conditioning', 'gene therapy', 'SCID newborn screening', 'TREC' and 'late effects'. Expert commentary: Newborn screening has dramatically changed the clinical presentation of newborn SCID. While the majority of patients with SCID survive HCT, data regarding late effects in these patients is limited and additional studies focused on genotype specific late effects are needed. Prospective studies aimed at minimizing the use of alkylating agents and reducing late effects beyond survival are needed. Gene therapy is being developed and will likely become a more commonly used treatment that will require separate consideration of survival and late effects.