Kappa-deleting Recombination Excision Circles 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.

Newborn Screening for Severe T and B Cell Lymphopenia Using TREC/KREC Detection: A Large-Scale Pilot Study of 202,908 Newborns.

Newborn screening (NBS) for severe inborn errors of immunity (IEI), affecting T lymphocytes, and implementing measurements of T cell receptor excision circles (TREC) has been shown to be effective in early diagnosis and improved prognosis of patients with these genetic disorders. Few studies conducted on smaller groups of newborns report results of NBS that also include measurement of kappa-deleting recombination excision circles (KREC) for IEI affecting B lymphocytes. A pilot NBS study utilizing TREC/KREC detection was conducted on 202,908 infants born in 8 regions of Russia over a 14-month period. One hundred thirty-four newborns (0.66‰) were NBS positive after the first test and subsequent retest, 41% of whom were born preterm. After lymphocyte subsets were assessed via flow cytometry, samples of 18 infants (0.09‰) were sent for whole exome sequencing. Confirmed genetic defects were consistent with autosomal recessive agammaglobulinemia in 1/18, severe combined immunodeficiency - in 7/18, 22q11.2DS syndrome - in 4/18, combined immunodeficiency - in 1/18 and trisomy 21 syndrome - in 1/18. Two patients in whom no genetic defect was found met criteria of (severe) combined immunodeficiency with syndromic features. Three patients appeared to have transient lymphopenia. Our findings demonstrate the value of implementing combined TREC/KREC NBS screening and inform the development of policies and guidelines for its integration into routine newborn screening programs.

Multiplex Real-Time PCR-Based Newborn Screening for Severe Primary Immunodeficiency and Spinal Muscular Atrophy in Osaka, Japan: Our Results after 3 Years.

In newborn screening (NBS), it is important to consider the availability of multiplex assays or other tests that can be integrated into existing systems when attempting to implement NBS for new target diseases. Recent developments in innovative testing technology have made it possible to simultaneously screen for severe primary immunodeficiency (PID) and spinal muscular atrophy (SMA) using quantitative real-time polymerase chain reaction (qPCR) assays. We describe our experience of optional NBS for severe PID and SMA in Osaka, Japan. A multiplex TaqMan qPCR assay was used for the optional NBS program. The assay was able to quantify the levels of T-cell receptor excision circles and kappa-deleting recombination excision circles, which is useful for severe combined immunodeficiency and B-cell deficiency screening, and can simultaneously detect the homozygous deletion of SMN1 exon 7, which is useful for NBS for SMA. In total, 105,419 newborns were eligible for the optional NBS program between 1 August 2020 and 31 August 2023. A case each of X-linked agammaglobulinemia and SMA were diagnosed through the optional NBS and treated at early stages (before symptoms appeared). Our results show how multiplex PCR-based NBS can benefit large-scale NBS implementation projects for new target diseases.

Associations of the placental metabolome with immune maturation up to one year of age in the Swedish NICE-cohort

IntroductionAllergies and other immune-mediated diseases are thought to result from incomplete maturation of the immune system early in life. We previously showed that infants’ metabolites at birth were associated with immune cell subtypes during infancy. The placenta supplies the fetus with nutrients, but may also provide immune maturation signals.ObjectivesTo examine the relationship between metabolites in placental villous tissue and immune maturation during the first year of life and infant and maternal characteristics (gestational length, birth weight, sex, parity, maternal age, and BMI).MethodsUntargeted metabolomics was measured using Liquid Chromatography-Mass Spectrometry. Subpopulations of T and B cells were measured using flow cytometry at birth, 48 h, one, four, and 12 months. Random forest analysis was used to link the metabolomics data with the T and B cell sub populations as well as infant and maternal characteristics.ResultsModest associations (Q2 = 0.2–0.3) were found between the placental metabolome and kappa-deleting recombination excision circles (KREC) at birth and naïve B cells and memory T cells at 12 months. Weak associations were observed between the placental metabolome and sex and parity. Still, most metabolite features of interest were of low intensity compared to associations previously found in cord blood, suggesting that underlying metabolites were not of placental origin.ConclusionOur results indicate that metabolomic measurements of the placenta may not effectively recognize metabolites important for immune maturation.

Assessment of trec and krec levels in COVID-19 patients with varying disease severity

According to the WHO data, the number of infected people exceeded 765.2 million people during the COVID-19 pandemic. The severity of patient’s condition is determined by immune system hyperactivation. Activation of T- and B-lymphocyte subsets plays a prominent role in the control of infectious process. A content of small circular DNA molecules — T-cell receptor excision circles (TREC — T-cell receptor excision circles) and B-cell (“kappa”) excision rings (KREC — Kappa-deleting recombination excision circles) — in the peripheral blood can be used as a marker of the functionally active T and B cells maturation. The purpose of this work is to quantify peripheral blood TREC and KREC level in patients with the new coronavirus infection COVID-19 of varying severity.Materials and methods.The material consisted of 1028 blood samples from patients with a confirmed diagnosis of COVID-19, as well as 717 blood samples from apparently healthy volunteers. The content of TREC and KREC DNA fragments in the total DNA fraction was assessed by quantitative Real-time PCR using the “TREC/KREC-AMP PS” test system (St. Petersburg Pasteur Institute, Russia). Blood cell phenotyping was carried out using flow cytometry.Results.TREC/KREC levels were significantly reduced in COVID-19 patients (p 0.0001 at 95% CI). A significant direct correlation was established between the levels of peripheral blood TREC molecules and level of CD45+CD3+CD19–T cells (r = 0.59, p 0.0001), as well as between KREC level and count of CD45+CD3–CD19+B cells (r = 0.66, p 0.0001). The level of TREC molecules in patients with severe vs. moderate infection was significantly reduced in patients aged 30–39 years old (p = 0.0404) and 40–49 years old (p = 0.0356). The negative correlation between severity of COVID-19 clinical manifestations and TREC level in the blood of patients in 30–49 year age group indicates about an opportunity of using this analyte as a diagnostic and prognostic laboratory marker of patient’s condition. A simple PCR analysis algorithm makes it relevant to use the described method for assessing a state of immunity in coronavirus patients in the context of systemic negative impact of the SARS-CoV-2 virus on human organism.

Importance of TREC and KREC as molecular markers for immunological evaluation of down syndrome children

Recurrent and severe infections occurred in children with Down Syndrome (DS) due to immunological parameter defects have been reported. The aim of the study is to evaluate the importance of using T-cell receptor excision circle (TREC) and kappa-deleting recombination excision circle (KREC) as molecular markers for immunological investigation of children with DS. The study included 40 non-disjunction trisomy 21 confirmed DS children, and 25 healthy controls. Peripheral blood (PB) was analyzed for lymphocyte subpopulations by flow cytometry, serum immunoglobulin levels, and TREC and KREC copy numbers using quantitative real-time PCR. DS patients showed significantly lower absolute counts of PB T lymphocytes, T helper lymphocytes, T cytotoxic lymphocytes, B lymphocytes, and Natural killer cells, and lower serum IgA, IgG, and IgM levels compared to healthy controls. Copy number of TREC and KREC showed no significant differences between DS patients and healthy controls. There is a significant positive correlation between TREC copy number with a percentage and absolute count of helper T lymphocytes in patients. Also, the KREC copy number was significantly negatively correlated with the age of patients. These findings suggest that copy numbers of TREC and KREC could be useful as molecular markers for immunological evaluation of patients with DS.

Expansion of the immature B lymphocyte compartment in Graves' disease.

The specific mechanisms driving autoimmunity in Graves' disease (GD) remain largely unknown. Kappa-deleting recombination excision circles (KRECs) are circular DNA molecules generated during B cell maturation in the bone marrow which provide a measure of B cell production and proliferation. We aimed to investigate the association between KRECs and B cell subpopulations, with thyroid status and clinical outcome in GD patients. Kappa-deleting recombination excision circles were measured by quantitative real-time PCR using a triple-insert plasmid control in 132 GD patients and 140 healthy controls. In addition, KRECs in GD patients on withdrawal of antithyroid drug (ATD) and 6-10 weeks later were analysed according to a clinical outcome at 1 year. Flow cytometry was performed on isolated CD19+ B cells to quantitate 7 B lymphocyte subpopulations in 65 GD patients. Circulating KRECs were higher in GD vs. controls (P = 1.5 × 10-9) and demonstrated a positive correlation to thyroid hormones and autoantibodies (free thyroxine: P = 2.14 × 10-5, rho = .30; free triiodothyronine: P = 1.99 × 10-7, rho = .37; thyroid stimulating hormone receptor autoantibodies: P = 1.36 × 10-5, rho = .23). Higher KRECs in GD patients 6-10 weeks after ATD withdrawal were associated with relapse of hyperthyroidism at 1 year (P = .04). The KRECs were positively correlated to the total CD19+ B cell count (P = 3.2 × 10-7). This study reports a robust association between KRECs and GD, highlighting the importance of B cells in the pathogenesis of GD and the influence of thyroid status on B cell activity. The findings indicate a potential role for KRECs as a marker of disease activity and outcome in GD.

Genomic-Based Newborn Screening for Inborn Errors of Immunity: Practical and Ethical Considerations

Inborn errors of immunity (IEI) are a group of over 450 genetically distinct conditions associated with significant morbidity and mortality, for which early diagnosis and treatment improve outcomes. Newborn screening for severe combined immunodeficiency (SCID) is currently underway in several countries, utilising a DNA-based technique to quantify T cell receptor excision circles (TREC) and kappa-deleting recombination excision circles (KREC). This strategy will only identify those infants with an IEI associated with T and/or B cell lymphopenia. Other severe forms of IEI will not be detected. Up-front, first-tier genomic-based newborn screening has been proposed as a potential approach by which to concurrently screen infants for hundreds of monogenic diseases at birth. Given the clinical, phenotypic and genetic heterogeneity of IEI, a next-generation sequencing-based newborn screening approach would be suitable. There are, however, several ethical, legal and social issues which must be evaluated in detail prior to adopting a genomic-based newborn screening approach, and these are discussed herein in the context of IEI.

A preliminary study of tracking B-cell kinetics in patients with lung transplantation by monitoring kappa-deleting recombination excision circles.

This study aims to evaluate humoral immune system response by measuring copy numbers of kappa-deleting recombination excision circles (KREC) gene segment from B lymphocytes in patients with lung transplantation. Between September 2015 and November 2016, a total of 11 patients (8 males, 3 females; mean age: 45.4±12.0 years; range, 23 to 59 years) who underwent lung transplantation with different primary indications were included. The copy numbers of KREC gene segment were quantified using real-time polymerase chain reaction method in peripheral blood samples collected pre- and post-transplantation. The samples of the patients were compared with the KREC l evels i n deoxyribonucleic acid extracted from blood samples of healthy children. There was no significant change in KREC levels between pre- and post-operation (p=0.594 and p=0.657), although the median values indicated that the highest increase in the KREC levels (7x105- 12x105; 85-170) was on Day 7 of transplantation. There was a positive correlation between the KREC levels (mL in blood) and lymphocytes at 24 h after transplantation (p=0.043) and between KREC copies per 106 of blood and age on Day 7. Our preliminary results suggest that KREC l evels a s an indicator of B lymphocyte production are elevated after lung transplantation. A prognostic algorithm by tracking B cell kinetics after post-transplantation for long-term follow-up can be developed following the confirmation of these preliminary results with more patient samples.

Клінічний випадок комбінованого імунодефіциту, діагностованого за допомогою визначення TREC

Early diagnosis and timely treatment of combined immunodeficiency (CID) is extremely important for the child’s future life. At birth, children often have no specific signs of the disease, but from the first months of life CID manifests by severe infections that can impact on the results of further treatment. Detection of T-cell lymphopenia by determining the number of T-cell receptor excision circles (TRECs) in a dry spot after the birth of a child formed the basis for newborn screening for severe CID. KREC (kappa-deleting recombination excision circle) assay is used for detection of B-cell lymphopenia. Clinical case. We report the first case of CID (T-B+NK+) suspected by detection of TREC in Ukraine in a 2.5-month-old child. Immunodeficiency was manifested by severe complicated pneumonia at the age of 2 months, which had an atypical course and was resistant to treatment. A screening study to detect T- and B-lymphopenia using the TREC/KREC assay twice showed a zero TREC value and a KREC number of 3.12×105 per 106 cells, indicating severe CID. Subsequent immunological studies confirmed the deficiency of T-cell immunity. Venous thrombosis and increasing multiorgan failure led to the death of the child. Thus, newborn screening using TREC assay will allow the timely detection of severe combined immunodeficiencies with further adequate therapy and measures to prevent life-threatening infections, including SARS-CoV-2. The research was carried out in accordance with the principles of the Helsinki Declaration. The informed consent of the patient was obtained for conducting the studies. No conflict of interests was declared by the authors.

T cell receptor excision circles are potential predictors of survival in adult allogeneic hematopoietic stem cell transplantation recipients with acute myeloid leukemia.

BackgroundLymphocyte neogenesis from primary lymphoid organs is essential for a successful reconstitution of immunity after allogeneic hematopoietic stem cell transplantation (HSCT). This single-center retrospective study aimed to evaluate T cell receptor excision circles (TREC) and kappa-deleting recombination excision circles (KREC) as surrogate markers for T and B cell recovery, as predictors for transplantation-related outcomes in adult acute myeloid leukemia (AML) patients.MethodsNinety adult patients diagnosed with AML and treated with HSCT between 2010 and 2015 were included in the study. TREC and KREC levels were measured by quantitative PCR at 1, 3, 6, and 12 months after transplantation.ResultsOverall, excision circle levels increased between 3 and 6 months post-HSCT for TREC (p = 0.005) and 1 and 3 months for KREC (p = 0.0007). In a landmark survival analysis at 12 months post-HSCT, TREC levels were associated with superior overall survival (HR: 0.52, 95% CI: 0.34 - 0.81, p = 0.004). The incidence of viral infections within the first 100 days after transplantation was associated with lower TREC levels at 6 months (p = 0.0002). CMV reactivation was likewise associated with lower TREC levels at 6 months (p = 0.02) post-HSCT. KREC levels were not associated with clinical outcomes in statistical analyzes.ConclusionsResults from the present study indicate that TREC measurement could be considered as part of the post-HSCT monitoring to identify AML patients with inferior survival after transplantation. Further prospective studies are warranted to validate these findings.

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 (TlowB+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.

TREC/KREC Newborn Screening followed by Next-Generation Sequencing for Severe Combined Immunodeficiency in Japan.

The aim of this study is to evaluate the usefulness of T cell receptor excision circle (TREC) and/or kappa-deleting recombination excision circle (KREC) measurements integrated with diagnostic next-generation sequencing (NGS) analysis using a severe combined immunodeficiency (SCID) newborn screening (NBS) program. TREC and/or KREC values were measured in 137,484 newborns between April 2017 and December 2021 using EnLite TREC (n = 80,791) or TREC/KREC kits (n = 56,693). For newborns with positive screening results, diagnostic NGS analysis was performed with a 349-gene panel to detect genetic mutations associated with primary immunodeficiencies (PIDs). A total of 145 newborns (0.11%) had abnormal TREC and/or KREC values, and a genetic diagnosis was established in 2 patients with SCID (1 in 68,742 newborns) (IL2RG-SCID and reticular dysgenesis) and 10 with non-SCID PIDs with T and/or B cell deficiencies (1 in 13,748 newborns) using NGS analysis. Furthermore, TREC values of 2849 newborns were measured and confirmed the significant correlation between the results of both TREC and TREC/KREC kits (P < 0.001) and naïve T cell counts. We performed the first large-scale TREC and TREC/KREC NBS programs in Japan. Our NBS programs followed by the diagnostic NGS analysis for newborns with abnormal TREC and/or KREC values are useful for the early identification and rapid molecular evaluation of not only SCID but also different non-SCID PIDs.

Coding joint: kappa-deleting recombination excision circle ratio and B cell activating factor level: predicting juvenile dermatomyositis rituximab response, a proof-of-concept study

BackgroundThis pilot study’s primary aim was to determine if oligoclonal B cell expansion in children with Juvenile Dermatomyositis (JDM) predicts response to Rituximab therapy. We evaluated: (1) tissue B cell depletion efficacy by measuring the ratio of Coding joint (CJ) to Kappa-deleting recombination excision circle (KREC) DNA, and (2) serum BAFF level upon B cell recovery.MethodsCJ and KREC values were measured via qPCR assessment of serial PBMC stored (− 80 °C) in the CureJM Center’s BioRepository. Serum BAFF was quantitated by Mesoscale® technology. Oligoclonal B cell expansion was defined as a CJ:KREC ≥ 8 prior to Rituximab therapy. Detection of a CJ:KREC ratio ≤ 2.5 in the first sample after Rituximab was designated as adequate B cell depletion. A significant clinical response to therapy was defined as improvement in Disease Activity Score (DAS) by at least 2 points on consecutive visits within the first 12 months of therapy.ResultsSix out of nine children with JDM showed oligoclonal B cell expansion prior to Rituximab (CJ:KREC ≥ 8). Of those 6 patients, 4 had evidence of effective B cell depletion after Rituximab (CJ:KREC ≤ 2.5), and all 4 of those subjects displayed a significant clinical response to Rituximab. Serum BAFF level increased in 8/9 children after Rituximab.ConclusionsIn this proof-of-concept study, JDM patients with oligoclonal B cell expansion prior to Rituximab have more favorable clinical outcomes after Rituximab. We speculate: (1) B cell depletion post-Rituximab predicts JDM clinical response; (2) increased BAFF post-Rituximab may contribute to disease flare.

TREC/KREC Levels and T and B Lymphocyte Subpopulations in COVID-19 Patients at Different Stages of the Disease.

Background: T and B cell-mediated immunity can be assessed using T cell receptor excision circle (TREC) and Kappa-deleting recombination excision circle (KREC) analysis, respectively, and successful implementation of this method requires evaluation of the correlation between the TREC frequencies and T cell subsets as well as KREC levels and B lymphocyte subsets. The aim of the present study was to evaluate the correlation between the TREC/KREC concentrations and T/B lymphocyte subsets at different stages of COVID-19. Methods: We examined 33 patients in the acute stage of COVID-19 (including 8 patients with poor outcomes) and 33 COVID-19 survivors. TREC/KREC concentrations were measured using quantitative real-time PCR. T/B lymphocyte subsets were determined using flow cytometry. Results: Blood TREC and KREC levels were found to be significantly lower in the acute stage of COVID-19 compared to control values. Moreover, a zero blood TREC level was a predictor of a poor disease outcome. Reductions in CD3+CD4+CD45RO−CD62L− and CD3+CD8+CD45RO−CD62L− T cell counts (as well as in the main fractions of B1 and B2 B cells) indicated a favorable outcome in COVID-19 patients in the acute stage of the disease. Decreased CD3+CD4+CD45RO−CD62L+ and CD3+CD8+CD45RO−CD62L+ T cell frequencies and increased CD3+CD8+CD45RO−CD62L− cell counts were found to indicate a poor outcome in patients with acute COVID-19. These patients were also found to have increased B1 cell counts while demonstrating no changes in B2 cell counts. The levels of effector T cell subsets an naïve B cells were normal in COVID-19 survivors. The most pronounced correlations between TREC/KREC levels and T/B cell subsets counts were observed in COVID-19 survivors: there were positive correlations with naïve T and B lymphocytes and negative correlations with central and effector memory T cell subsets. Conclusions: The assessment of correlations between TREC and T cell subsets as well as KREC levels and B cell subset counts in patients with acute COVID-19 and COVID-19 survivors has shown that blood concentrations of TREC and KREC are sensitive indicators of the stage of antigen-independent differentiation of adaptive immunity cells. The results of the TREC and KREC analysis correlated with the stages of COVID-19 and differed depending on the outcome of COVID-19.

B cell repertoire in patients with a novel BTK mutation: expanding the spectrum of atypical X-linked agammaglobulinemia.

X-linked agammaglobulinemia (XLA) is caused by mutations in the Bruton tyrosine kinase) BTK) gene. Affected patients have severely reduced amounts of circulating B cells. Patients with atypical XLA may have residual circulating B cells, and there are few studies exploring these cells' repertoire. We aimed to study the B cell repertoire of a novel hypomorphic mutation in the BTK gene, using the next generation sequencing (NGS) technology. Clinical data was collected from our clinical records. Real-time PCR was used to determine KREC copies, and NGS was used to determine the immunoglobulin (Ig) heavy chain (IgH) repertoire diversity. Both patients had a relatively mild clinical and laboratory phenotype, residual BTK protein expression, and the same novel mutation in the BTK gene, c.1841T > C, p. L614P. Signal-joint kappa-deleting recombination excision circles (sj-KREC) for both patients were completely absent reflecting lack of naïve B cells. The intron RSS-Kde coding joints (cj) were significantly reduced, reflecting residual replicating B cells. NGS displayed restricted IgH repertoire with highly uneven distribution of clones, especially for Pt2. We report a novel BTK mutation, c.1841T > C (p. L614P) that is associated with a relatively mild phenotype. We conclude that the IgH repertoire in atypical XLA is restricted with highly uneven distribution of clones. This phenomenon may be explained by extremely reduced to non-existent levels of BTK in B cells. This report sheds further light on atypical cases of XLA.

Кожные проявления первичных иммунодефицитных состояний

Primary immune deficiency diseases (PIDDs) are a group of severe genetically determined diseases caused by a disorder of the immunity links: humoral and cell-mediated links, phagocytosis, complement system. PIDDs are characterized by severe atypical recurrent infections, as well as autoimmune and oncological processes. In the case of clinical symptoms, skin manifestations in PIDDs allow to suspect the presence of congenital disorders of immunity. There is a technique in laboratory diagnostics of PIDDs, that determines a decrease in the number of T- and B-lymphocytes based on measuring the levels of TREC (T-cell Receptor Excision Circle) and KREC (Kappa-deleting Recombination Excision Circle), which are by-products of recombination of T- and B-cell receptor genes. TREC and KREC levels can be assessed using a reagent kit for quantifying TREC and KREC DNA by PCR in real time. The analysis can be conducted using both whole blood and DNA obtained from dried blood stains collected during the national newborn screening program. Today, quantitative analysis of TREC and KREC in dried blood stains on newborn screening cards is becoming the method of choice for newborn screening of PIDDs. The inclusion of the PIDDs diagnosis in the federal newborn screening program will allow detecting disorders of the immune system before their clinical manifestations, which will allow to apply modern treatment protocols, reduce disability and ensure high patient survival. KEYWORDS: TREC, KREC, PIDDs, newborn screening, PCR, immunity, early diagnosis. FOR CITATION: Churyukina E.V., Kudlay D.A. Skin manifestations of primary immune deficiency diseases. Russian Medical Inquiry. 2022;6(2):98–104 (in Russ.). DOI: 10.32364/2587-6821-2022-6-2-98-104

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.

Diagnostic and therapeutic approach to children with Nijmegen breakage syndrome in relation to development of lymphoid malignancies.

Nijmegen breakage syndrome (NBS) is a rare chromosomal instability disorder. The majority of patients carry founder mutation in the NBN gene (c.657_661del5). Characteristic features of the NBS include progressive microcephaly, dysmorphic facial features, immunodeficiency, and high predisposition to malignancy with cumulative cancer incidence by the age of 20 years, and amounted to over 70%. The aim of study is to present the latest methods of diagnosis, potential cancer risk factors and treatment of lymphoid malignancies in children with NBS. To review the evidence using PubMed and Google Scholar search which included articles published between 2009-2021, focusing on articles published between 2013-2021. The average delay in diagnosis of NBS ranges from 4-5 years. Neonatal screening of T-cell excision circles (TRECs) and kappa-deleting recombination excision circles (KRECs) seems favourable in NBS. There are no specific protocols for the treatment of lymphoid malignancies in children with NBS, and full- dose chemotherapy is the most frequently applied method. Reducing the doses of chemotherapy does not significantly reduce the toxicity. Main cause of death is cancer progression and treatment-related mortality mostly associated with infectious complications. Patients with diagnosed cancer who received haematopoietic stem cell transplantation (HSCT) had significantly higher 20-year OS than those who did not (42.7% vs. 30.3%). Further meta-analysis is essential to establish the best monitoring and treatment regimen in patients with NBS and lymphoid malignancies.

Diagnosis of immunodeficiency conditions. Overview of the training event. Speakers I.N. Zakharova, I.A. Korsunsky

Primary immunodeficiencies (PIDs) are a heterogeneous group of genetic diseases. When PID is suspected, first of all, it is necessary to carefully collect the anamnesis, identify the features of clinical symptoms and the course of diseases in the child. To confirm the diagnosis, laboratory and instrumental methods of examination, immunological examination, and molecular genetic analysis are evaluated. As part of the immunological examination, as a screening method for detecting abnormalities in the T and B-cell parts of the immune system, a technique can be used to measure TREC (T-cell Receptor Excision Circle) and KREC (Kappa-deleting Recombination Excision Circle) levels by-products of T and B-cell receptor formation. A decrease in the amount of TREC and/or KREC in the blood indicates the presence of cellular PID. The assay can be performed using both whole blood and dried blood spots in children and adults.