Lipopolysaccharide-responsive Beige-like Anchor Research Articles

An efficient and successful outcome after haematopoietic stem cell transplantation in a patient with an LPS-responsive beige-like anchor gene mutation

An efficient and successful outcome after haematopoietic stem cell transplantation in a patient with an LPS-responsive beige-like anchor gene mutation

Lipopolysaccharide-responsive beige-like anchor is involved in regulating NF-κB activation in B cells

IntroductionLipopolysaccharide-responsive and beige-like anchor (LRBA) is a scaffolding protein that interacts with proteins such as CTLA-4 and PKA, the importance of which has been determined in various cell types, including T regulatory cells, B cells, and renal cells. LRBA deficiency is associated with an inborn error in immunity characterized by immunodeficiency and autoimmunity. In addition to defects in T regulatory cells, patients with LRBA deficiency also exhibit B cell defects, such as reduced cell number, low memory B cells, hypogammaglobulinemia, impaired B cell proliferation, and increased autophagy. Although Lrba-/- mice do not exhibit the immunodeficiency observed in humans, responses to B cell receptors (BCR) in B cells have not been explored. Therefore, a murine model is for elucidating the mechanism of Lrba mechanism in B cells.AimTo compare and evaluate spleen-derived B cell responses to BCR crosslinking in C57BL6 Lrba-/- and Lrba+/+ mice.Materials and methodsSpleen-derived B cells were obtained from 8 to 12-week-old mice. Subpopulations were determined by immunostaining and flow cytometry. BCR crosslinking was assessed by the F(ab’)2 anti-μ chain. Activation, proliferation and viability assays were performed using flow cytometry and protein phosphorylation was evaluated by immunoblotting. The nuclear localization of p65 was determined using confocal microscopy. Nur77 expression was evaluated by Western blot.ResultsLrba-/- B cells showed an activated phenotype and a decreased proportion of transitional 1 B cells, and both proliferation and survival were affected after BCR crosslinking in the Lrba-/- mice. The NF-κB pathway exhibited a basal activation status of several components, resulting in increased activation of p50, p65, and IκBα, basal p50 activation was reduced by the Plcγ2 inhibitor U73122. BCR crosslinking in Lrba-/- B cells resulted in poor p50 phosphorylation and p65 nuclear localization. Increased levels of Nur77 were detected.DiscussionThese results indicate the importance of Lrba in controlling NF-κB activation driven by BCR. Basal activation of NF-κB could impact cellular processes, such as, activation, differentiation, proliferation, and maintenance of B cells after antigen encounter.

False Negative Next-Generation-Sequencing Analysis in a Lipopolysa ccharide-Responsive Beige-Like Anchor Defect.

False Negative Next-Generation-Sequencing Analysis in a Lipopolysa ccharide-Responsive Beige-Like Anchor Defect.

Genome‐wide association meta‐analysis identifies a novel LRBA locus for brain age acceleration in two independent Korean Cohorts

AbstractBackgroundAging is a key risk factor for Alzheimer’s disease (AD) and has a significant structural impact on the brain. Machine learning approaches have been developed to estimate the biological age of the brain from MRI scans. Here, we performed genome‐wide association (GWA) analysis of accelerated brain aging in two independent Korean AD cohorts.MethodParticipants included 1,738 Korean older adults from two independent cohorts that consisted of preclinical and clinical stages of AD (n = 1,209 from the K‐ROAD cohort (Korea‐Registries to Overcome and Accelerate Dementia Research Project) and n = 529 from the KBASE cohort (Korean Brain Aging Study for the Early Diagnosis and Prediction of Alzheimer’s Disease)). Brain age was estimated from structural MRI scans using brainageR. Brain age acceleration (predicted brain age ‐ chronological age) was calculated for each participant. Genetic variants associated with brain age acceleration were assessed after accounting for age, sex, APOE e4 carrier status, and diagnosis. Meta‐analysis was performed using METAL, followed by transcriptomic analysis. Polygenic risk scores for brain age acceleration were calculated with PRS‐CS using GWAS meta‐analysis summary statistics, followed by molecular imaging analysis.ResultGWA meta‐analysis identified six intronic SNPs in the LRBA (Lipopolysaccharide responsive Beige‐like Anchor) locus on chromosome 4 as significantly associated with brain age acceleration with the most significant signal at rs7699001 (Fig. 1; p<5´10−8). LRBA is highly expressed in the brain, especially in microglia. The LRBA gene is differentially expressed in AD compared to cognitively normal older adults. rs7699001 was associated with expression levels of the LRBA gene in tissue from several organs including brain. rs7690001 has been reported to be associated with inferior parietal cortical thickness in non‐Hispanic whites (p = 5´10−3). Polygenic risk scores of brain age acceleration in the K‐ROAD cohort were significantly associated with amyloid‐β deposition measured from amyloid PET scans (Fig. 2; p = 2.7´10−4).Conclusion LRBA is a novel genetic risk factor for brain aging in the Korean population with relevance for AD. The microglial LRBA protein may be involved in phagocytosis, which has been implicated in aging processes and AD progression. Replication in other populations and mechanistic follow‐up studies are warranted.This work was supported by U01AG072177.

LRBA signalosomes activate vasopressin-induced AQP2 trafficking at recycling endosomes.

Aquaporin-2 (AQP2) water channels are proteins that are recycled between intracellular vesicles and the apical plasma membrane in renal collecting ducts. Lipopolysaccharide-responsive beige-like anchor protein (LRBA) is a protein kinase A (PKA) anchoring protein that creates compartmentalized PKA signalling responsible for AQP2 phosphorylation. In response to increased plasma osmolality, vasopressin/cyclic adenosine monophosphate (cAMP)/PKA signalling phosphorylates AQP2, promoting AQP2 trafficking into the apical plasma membrane and increasing water reabsorption from urine. However, the molecular mechanisms by which LRBA mediates vasopressin-induced AQP2 phosphorylation remain unknown. To investigate AQP2 intracellular localization and phosphorylation status in vivo, a density gradient ultracentrifugation technique was combined with an in situ proximity ligation assay, super-resolution structured illumination microscopy and immunoelectron microscopy. Most of the AQP2 was localized on the recycling endosome in the presence of tolvaptan, a vasopressin type 2 receptor (V2R) antagonist. Desmopressin, a V2R agonist, phosphorylated AQP2, translocating it from the recycling endosome to the apical plasma membrane. In contrast, LRBA was constitutively localized at the recycling endosome. Therefore, LRBA and AQP2 were well colocalized in the absence of vasopressin stimulation. The loss of LRBA/PKA signalling by Lrba knockout impaired vasopressin-induced AQP2 phosphorylation, resulting in AQP2 retention at the recycling endosome. Defective AQP2 trafficking caused low urinary concentrating ability in Lrba-/- mice. The LRBA-PKA complex created compartmentalized PKA signalling at the recycling endosome, which facilitated AQP2 phosphorylation in response to vasopressin. KEY POINTS: Membrane proteins are continuously internalized into the endosomal system via endocytosis, after which they are either recycled back to the plasma membrane or degraded at the lysosome. In T cells, lipopolysaccharide-responsive beige-like anchor protein (LRBA) binds directly to the cytotoxic T lymphocyte antigen 4 (CTLA-4), a checkpoint immune molecule, to prevent CTLA-4 lysosomal degradation and promote its vesicle recycling. LRBA has different physiological functions in renal collecting ducts. LRBA and aquaporin-2 (AQP2) water channels were colocalized on the recycling endosome in vivo in the absence of the anti-diuretic hormone vasopressin. LRBA promoted vasopressin-induced AQP2 trafficking, increasing water reabsorption from urine via AQP2. LRBA determined renal responsiveness to vasopressin at recycling endosomes. LRBA is a ubiquitously expressed anchor protein. LRBA signalosomes might regulate membrane trafficking of several constitutively recycled proteins at recycling endosomes.

Therapeutic modalities and clinical outcomes in a large cohort with LRBA deficiency and CTLA4 insufficiency

LPS-responsive beige-like anchor (LRBA) deficiency (LRBA-/-) and cytotoxic T-lymphocyte-associated antigen-4 (CTLA4) insufficiency (CTLA4+/-) are mechanistically overlapped diseases presenting with recurrent infections and autoimmunity. The effectiveness of different treatment regimens remains unknown. Our aim was to determine the comparative efficacy and long-term outcome of therapy with immunosuppressants, CTLA4-immunoglobulin (abatacept), and hematopoietic stem cell transplantation (HSCT) in a single-country multicenter cohort of 98 patients with a 5-year median follow-up. The 98 patients (63 LRBA-/- and 35 CTLA4+/-) were followed and evaluated at baseline and every 6 months for clinical manifestations and response to the respective therapies. The LRBA-/- patients exhibited a more severe disease course than did the CTLA4+/- patients, requiring more immunosuppressants, abatacept, and HSCT to control their symptoms. Among the 58 patients who received abatacept as either a primary or rescue therapy, sustained complete control was achieved in 46 (79.3%) without severe side effects. In contrast, most patients who received immunosuppressants as primary therapy (n= 61) showed either partial or no disease control (72.1%), necessitating additional immunosuppressants, abatacept, or transplantation. Patients with partial or no response to abatacept (n= 12) had longer disease activity before abatacept therapy, with higher organ involvement and poorer disease outcomes than those with a complete response. HSCT was performed in 14 LRBA-/- patients; 9 patients (64.2%) showed complete remission, and 3 (21.3%) continued to receive immunosuppressants after transplantation. HSCT and abatacept therapy gave rise to similar probabilities of survival. Abatacept is superior to immunosuppressants in controlling disease manifestations over the long term, especially when started early, and it may provide a safe and effective therapeutic alternative to transplantation.

A circular RNA produced by LRBA promotes cirrhotic mouse liver regeneration through facilitating the ubiquitination degradation of p27.

Accumulating circular RNAs (circRNAs) play important roles in tissue repair and organ regeneration. However, the biological effects of circRNAs on liver regeneration remain largely unknown. This study aims to systematically elucidate the functions and mechanisms of circRNAs derived from lipopolysaccharide-responsive beige-like anchor protein (LRBA) in regulating liver regeneration. CircRNAs derived from mouse LRBA gene were identified using CircBase. In vivo and in vitro experiments were conducted to confirm the effects of circLRBA on liver regeneration. RNA pull-down and RNA immunoprecipitation assays were used to investigate the underlying mechanisms. Clinical samples and cirrhotic mouse models were used to evaluate the clinical significance and transitional value of circLRBA. Eight circRNAs derived from LRBA were registered in CircBase. The circRNA mmu_circ_0018031 (circLRBA) was significantly upregulated in the liver tissues after 2/3 partial hepatectomy (PHx). Adeno-associated virus serotype 8 (AAV8)-mediated knockdown of circLRBA markedly inhibited mouse liver regeneration after 2/3 PHx. In vitro experiments confirmed that circLRBA exerted its growth-promoting function mainly through liver parenchymal cells. Mechanistically, circLRBA acted as a scaffold for the interaction between E3 ubiquitin-protein ligase ring finger protein 123 and p27, facilitating the ubiquitination degradation of p27. Clinically, circLRBA was lowly expressed in cirrhotic liver tissues and negatively correlated with perioperative levels of total bilirubin. Furthermore, overexpression of circLRBA enhanced cirrhotic mouse liver regeneration after 2/3 PHx. We conclude that circLRBA is a novel growth promoter in liver regeneration and a potential therapeutic target related to deficiency of cirrhotic liver regeneration.

An Unreported homozygous variant within Lipopolysaccharide responsive beige-like anchor (LRBA) gene in a child exhibiting with infantile type 1 diabetes mellitus

We report a patient who was born at term as the first son of consanguineous Saudi parents. He developed IDDM at the age of 7 months; the initial symptoms included fever and vomiting. The laboratory findings indicated pronounced ketoacidosis, initial fluid replacement with normal saline, followed by continuous IV insulin infusion. After a while, the baby was out of DKA. Our endocrinologist advised us to start administering S/C insulin NPH 1 unit BID. Fortunately, we suspected a primary immune deficiency acer a few days from the first presentation. The WES revealed A homozygous likely pathogenic variant was identified in the LRBA gene. The result is consistent with a genetic diagnosis of autosomal recessive CVID type 8 with autoimmunity. The LRBA protein regulates the expression of CTLA-4, which is a potent immune checkpoint receptor expressed by activated and regulatory by the T-cells. CTLA-4 blocks the stimulation/proliferation of T-cells and modulates immune responses.

Interstitial cystitis caused by immune dysregulation in LRBA deficiency: one among the rare urological manifestations in inborn errors of immunity

Inborn errors of immunity (IEI) rarely present with associated urological manifestations. Chronic cystitis and urethritis caused by ureaplasma and mycoplasma infection in hypogammaglobulinemia may result in bladder fibrosis. Papovaviridae such as BK or JC, can cause hemorrhagic cystitis in patients with T cell defects. Bladder granulomtata and urethral strictures can occur in chronic granulomatous disease. This is the first reported case of severe lymphocytic interstitial cystitis in a patient with lipopolysaccharide-responsive beige-like anchor protein (LRBA) deficiency. LRBA deficiency is known to impair CTLA-4 recycling, leading to decreased Treg cell function. A 13 year old male refugee presented with chronic recurrent debilitating suprapubic pain and dysuria, which progressed to extreme urinary frequency. He had a prior history of recurrent aseptic urinary tract infections, and one episode of gross hematuria. Extensive infectious investigations of urine (bacterial, mycobacterial cultures; viral PCRs), blood, and stool (Schistosoma) failed to isolate a pathogen. Bladder biopsy was positive for EBV by PCR but blood remained EBV-negative. Urinalysis showed microscopic hematuria while urodynamic studies were normal, and cystoscopy showed bladder and urethral irritation. Pathology confirmed lymphocytic interstitial cystitis, with primarily T cell infiltration. Immunological investigations revealed low IgG, IgA and IgM levels, B lymphopenia (1%), with low class-switched memory B cell development (3%) and absent response to protein and polysaccharide vaccine antigens. There were no signs of autoimmunity. Parents are consanguineous, and a sibling was likewise diagnosed with LRBA deficiency. Sanger sequencing of DNA confirmed the same homozygous family mutation in the LRBA gene, a likely pathogenic splice donor variant, c.2258+2T>G. The patient was started on immunoglobulin replacement. Trials of analgesics including NSAIDs, gabapentin, and morphine, and immunosuppression with corticosteroids and sirolimus, were unsuccessful in reducing urinary symptoms. Physiotherapy and antispasmodics were introduced when pelvic-floor dyssynergia with rectal pain developed. Subsequently-presenting enteropathy was managed with Abatacept (CTLA-4 IgG1 fusion protein), ultimately improving bladder symptoms after several months of therapy. Patient has since undergone HSCT and is now free of urinary tract symptoms. LRBA deficiency presents with hypogammaglobulinemia, infections, and immune dysregulation presenting with lymphocytic infiltration of non-lymphoid organs. This report highlights the phenotypic diversity of this disease.

Identification of novel compound heterozygous LRBA mutations associated with recurrent hemophagocytic lymphohistiocytosis and CNS manifestations

Background: Lipopolysaccharide-responsive beige-like anchor (LRBA) is an intracellular protein that regulates the recycling of cytotoxic T lymphocyte-associated protein 4 (CTLA4), an immune checkpoint molecule which prevents ongoing activation of T cells. Deficiency of LRBA results in increased trafficking and degradation of CTLA4, and consequently, uncontrolled T cell responses. The phenotypic spectrum of LRBA deficiency arising from biallelic loss-of-function typically includes recurrent infections, autoimmunity, lymphoproliferation, chronic diarrhea, hypogammaglobulinemia, and cytopenia. Aim: To report an atypical presentation of LRBA deficiency arising from a set of compound heterozygous LRBA variants, encompassing recurrent hemophagocytic lymphocytosis (HLH) and neurological manifestations. Methods: Clinical data was gathered through retrospective chart review. Expanded genetic analysis including whole exome sequencing was performed. Results: Our patient initially presented at age 15 months with fever, seizures, and encephalopathy. HLH-work-up showed bicytopenia, elevated ferritin and triglyceride, and low fibrinogen, however, he did not yet meet the diagnostic criteria for HLH. MRI brain and EEG at diagnosis was suggestive of acute necrotizing encephalopathy of childhood. He responded to pulsed IV methylprednisolone treatment with minimal residual neurological deficit on follow-up. At 36 months of age, he had a repeat presentation and rapidly deteriorated. He developed severe encephalopathy with fixed dilated pupils. Whole exome sequencing revealed a set of compound heterozygous missense variants in the LRBA gene, a novel c.2206A>T (p.R736W) and c.5989C>T (p.R1997C) variant. Conclusion: Compound heterozygous mutations in the LRBA gene caused an atypical presentation of recurrent HLH with central nervous system (CNS) manifestations in our patient. Statement of Novelty: We herein report a novel set of compound heterozygous mutations in LRBA with atypical presentation of recurrent HLH with CNS manifestations, thus expanding the known phenotypic spectrum of LRBA deficiency.

P-Element-Induced Wimpy Testis Proteins and P-Element-Induced Wimpy Testis-Interacting RNAs Expression in Ovarian Cancer Stem Cells.

Background: P-element-induced wimpy testis (PIWI)-interacting RNAs (piRNAs) are a type of noncoding RNA and are predominantly expressed in germline cells. piRNAs function as gene regulators and potential biomarkers for the development of a number of malignancies. The biological importance of piRNAs in ovarian cancer is still unknown. In this study, we investigated the expression of piRNAs in ovarian cancer stem cells and compared it with that in adherent cells. Methods: To assess changes in the expression levels of PIWIL1/HIWI, PIWIL2/HILI, PIWIL3, and PIWIL4/HIWI2, we used quantitative reverse-transcription polymerase chain reaction (RT-qPCR) analysis. Changes in piRNA expression levels in ovarian cancer stem cells were analyzed using Arraystar piRNA microarray screening. Gene Ontology (GO) enrichment analysis was conducted to determine the potential functions of piRNAs. Results: Using microarray analysis, we identified a cohort of differentially expressed piRNAs. Fifteen piRNAs, including DQ570763 and DQ597396, were downregulated, and 58 piRNAs were upregulated when compared with those in adherent A2780 and SKOV3 cells (p > 0.05, >2.0, respectively). GO functions of the downregulated piRNAs (DQ570763 and DQ570797) suggest that their roles are commonly associated with the Golgi apparatus. In addition, A2780-SP and SKOV3-SP cells had higher PIWIL3 and PIWIL4 mRNA levels than adherent cells (A2780 and SKOV3). Moreover, we determined, using receiver operating characteristic plot, that the expression level of PIWIL4 was lower in responders than in nonresponders after treatment with platins in patients with ovarian cancer. Finally, in ovarian cancer, PIWIL4 expression was associated with somatic mutations of dynein axonemal heavy chain 2, signal induced proliferation associated 1 like 2, YTH N6-methyladenosine RNA-binding protein 1, TBC1 domain family member 8, and LPS responsive Beige-like anchor protein. Conclusion: Our study showed that PIWI proteins and piRNAs are potential diagnostic and prognostic biomarkers for ovarian cancer.

Case Report: An Unreported Homozygous Variant within Lipopolysaccharide Responsive Beige-Like Anchor (LRBA) Gene in a Child Exhibiting with Infantile Type 1 Diabetes Mellitus

Case Report: An Unreported Homozygous Variant within Lipopolysaccharide Responsive Beige-Like Anchor (LRBA) Gene in a Child Exhibiting with Infantile Type 1 Diabetes Mellitus

AN ATYPICAL PRESENTATION OF LIPOPOLYSACCHARIDE-RESPONSIVE BEIGE-LIKE ANCHOR PROTEIN DEFICIENCY

<h3>Introduction</h3> Lipopolysaccharide-responsive beige-like anchor (LRBA) protein deficiency is associated with diarrhea, autoimmune disorders, organomegaly, recurrent infections, hypogammaglobulinemia, chronic lung manifestations, and growth retardation. However, LRBA mutations show a wide range of phenotypic variability. We present a case of a sixteen-year-old girl with a variant of uncertain significance (VUS) in the LRBA gene with atypical symptoms of LRBA deficiency. <h3>Case Description</h3> The patient is a sixteen-year-old female with type one diabetes mellitus, chronic urticaria, and idiopathic anaphylaxis requiring admission. Her complete blood count with differential, B and T cell phenotyping, and immunoglobulin levels were normal. She failed high dose antihistamines and omalizumab. Due to atypical symptoms, including soft tissue swelling, joint pains, recurrent abdominal pain, and elevated interleukin 10, interleukin 6, and S100 during an episode, we obtained an auto-inflammatory panel that showed a heterozygous VUS mutation in the LRBA gene. Parental LRBA testing showed the variants were trans-acting, increasing the likelihood that the variants contribute to her phenotype. She was started on abatacept with hydroxychloroquine, which improved her symptoms. <h3>Discussion</h3> This case highlights an atypical presentation of LRBA deficiency presenting with chronic urticaria and idiopathic anaphylaxis with a normal immune work up, symptoms of which are responsive to abatacept and hydroxychloroquine.

NOVEL HETEROZYGOTE MUTATION OF LRBA ASSOCIATED WITH CVID

<h3>Introduction</h3> Common variable immunodeficiency (CVID) is a clinically heterogeneous disorder with a growing list of genetic causes. The LPS Responsive Beige-Like Anchor (LRBA) gene encodes for a protein that is part of the CTLA-4 pathway important in immune regulation. Heterozygote mutations of this gene have been described in the literature in patients with CVID. We present a novel undescribed heterozygote LRBA mutation in the setting of CVID. <h3>Case Description</h3> We present a 69-year-old white male with diagnosed CVID. He was first diagnosed in his teenage years after frequent upper and lower respiratory tract infections. He has received intravenous immunoglobulin therapy since his diagnosis. His comorbidities include asthma, hypertension, hyperlipidemia, sciatica, and Hashimoto Thyroiditis. Recently genetic testing was done through Invitae^TM genomic DNA hybridization-based protocol with Illumina sequencing technology. The results showed a heterozygous LRBA c.6352del(p.11e2118Serfs*46) mutation. <h3>Discussion</h3> LRBA deficiency is seen in many different autoimmune conditions due to its importance in the regulation of immune responses. This heterozygous mutated gene has been seen in the setting of CVID in the literature. We present a novel heterozygous LRBA mutation in the clinical setting of CVID. The relationship between genotyping and the differing CVID phenotypes has not been widely explored. The discovery of this mutation will aid in establishing a more stable relationship between mutations and clinical signs and symptoms of CVID.

Clinically Complex LRBA Deficiency Due to a Founder Allele in the Georgian Jewish Population.

Pathogenic variants in LRBA, encoding the LPS Responsive Beige-Like Anchor (LRBA) protein, are responsible for recessive, early-onset hypogammaglobulinemia, severe multi-organ autoimmunity, and lymphoproliferation, with increased risk for malignancy. LRBA deficiency has a wide clinical spectrum with variable age of onset and disease severity. Three apparently unrelated patients with LRBA deficiency, of Georgian Jewish descent, were homozygous for LRBA c.6640C > T, p.R2214*, leading to a stop upstream of the LRBA BEACH domain. Despite carrying the same LRBA genotype, the three patients differed in clinical course: the first patient was asymptomatic until age 25years; the second presented with failure to thrive at age 3months; and the third presented at age 7years with immune cytopenias and severe infections. Two of the patients developed malignancies: the first patient was diagnosed with recurrent Hodgkin's disease at age 36years, and the second patient developed aggressive gastric cancer at age 15years. Among Georgian Jews, the carrier frequency of the LRBA p.R2214* allele was 1.6% (4 of 236 Georgian Jewish controls). The allele was absent from other populations. Haplotype analysis showed a shared origin of the mutation. These three patients revealed a pathogenic LRBA founder allele in the Georgian Jewish population, support the diverse and complex clinical spectrum of LRBA deficiency, and support the possibility that LRBA deficiency predisposes to malignancy.

Targeted next-generation sequencing revealed a novel homozygous mutation in the LRBA gene causes severe haemolysis associated with Inborn Errors of Immunity in an Indian family.

ABSTRACT Objectives LPS-responsive beige-like anchor protein (LRBA) deficiency abolishes LRBA protein expression due to biallelic mutations in the LRBA gene that lead to autoimmune manifestations, inflammatory bowel disease, hypogammaglobulinemia in early stages, and variable clinical manifestations. Materials and methods Mutational analysis of the LRBA gene was performed in Indian patients using targeted Next Generation Sequencing (t-NGS) and confirmed by Sanger sequencing using specific primers of exons 53. Then, bioinformatics analysis and protein modeling for the novel founded mutations were also performed. The genotype, phenotype correlation was done according to the molecular findings and clinical features. Results We report an unusual case of a female patient born of a consanguineous marriage, presented with severe anaemia and jaundice with a history of multiple blood transfusions of unknown cause up to the age of 5 yrs. She had hepatosplenomegaly with recurrent viral and bacterial infections. Tests for hemoglobinopathies, enzymopathies, and hereditary spherocytosis were within the normal limits. The t-NGS revealed a novel homozygous missense variation in exon 53 of the LRBA gene (chr4:151231464C > T; c.7799G > A) (p.C2600Y), and the parents were heterozygous. The further immunological analysis is suggestive of hypogammaglobulinaemia and autoimmune haemolytic anaemia. The bioinformatics tools are suggestive of deleterious and disease-causing variants. Conclusion This study concludes the importance of a timely decision of targeted exome sequencing for the molecular diagnostic tool of unexplained haemolytic anaemia with heterogeneous clinical phenotypes.

The Effects of Stimulation with PMA/Ionomycin on CD4+ T Cell Proliferation and Surface CD4 Molecule Modulation of Patients with LRBA Deficiency and CVID with the Unsolved Genetic Defect.

Common variable immunodeficiency (CVID) is the most prevalent symptomatic primary immunodeficiencies. LPS-responsive beige-like anchor protein (LRBA) deficiency is a combined immunodeficiency characterized by a CVID-like phenotype. Affected patients by LRBA and CVID present a wide range of clinical manifestations, including hypogammaglobulinemia, recurrent infections, autoimmunity, as well as T cell abnormality. The study population comprised of patients with CVID (n=10), LRBA deficiency (n=11), and healthy controls (n=12). CD4+ T cell frequency and CD4 MFI (mean fluorescence intensity) were evaluated using flow cytometry before and after stimulation with PMA/ION. The frequencies of CD4+ T cells were significantly lower in patients with LRBA deficiency than in HCs before and after treatment. In the unstimulated state, the CD4+ T cells frequency in CVID patients was significantly lower than in HCs. There were no statistically significant differences between patients and healthy individuals in CD4+ T cell proliferation. Compared to HCs, LRBA and CVID patients showed a lower CD4 MFI in unstimulated conditions. Furthermore, CD4 MFI decreased in both patients and the control group following activation. Despite the reported decrease in CD4+ T cell frequency in patients with CVID and LRBA deficiency, our findings demonstrated that their CD4+ T cells have a normal proliferative response to stimuli similar to healthy individuals.

Joint Involvement in Patients with LPS-Responsive and Beige-Like Anchor Protein (LRBA) Deficiency: A Case Report and Literature Review

Background: Lipopolysaccharide-responsive beige-like anchor (LRBA) deficiency is an inborn error of immunity characterized by a heterogeneous spectrum of manifestations, including enteropathy, immune dysregulation, and autoimmune disorder. Joint involvement has been less frequently reported, and limited data regarding its clinical presentation in LRBA deficiency has been published.&#x0D; Case presentation and review results: We reported an Iranian girl who was initially presented with recurrent respiratory tract infections and otitis media, later complicated by arthritis, growth failure, and organomegaly. The diagnosis of LRBA deficiency was confirmed by the identification of a novel homozygous missense variant in the LRBA gene (c.7742T&gt;A, p.M2581K). Along with this report, a literature review focused on joint involvement, on 26 patients with LRBA deficiency was performed.&#x0D; Conclusion: Non-infectious manifestations such as joint involvement have a broad spectrum in LRBA deficiency. For the timely diagnosis and appropriate clinical management, LRBA deficiency should always be kept in mind as a differential diagnosis in patients with joint involvement and clinically typical immune dysregulation.

Comparison of Clinical Manifestations, Immunological Analyses Between LRBA and CVID Patients: A Longitudinal Study

Background: Common variable immunodeficiency (CVID), is generally recognized as the most frequent type of Symptomatic primary immunodeficiencies (PID). Mutations in lipopolysaccharideresponsive beige-like anchor protein (LRBA) gene, are the most common genetic alterations amongst CVID patients. To date, there are no published studies to compare clinical and immunologic features of LRBA-deficient patients with those who do not harbor any known genetic mutations. Therefore, this study aims to compare the clinical manifestations and laboratory findings of Iranian patients with LRBA-deficiency and CVID with no known genetic alterations.&#x0D; Methods: We performed a longitudinal study on patients who had been diagnosed with CVID. Demographic and clinical features were obtained via the databank of the Iranian Registry of Primary Immunodeficiencies, and the direct interviews with patients. To assess the presence of LRBA or other genetic mutations, whole-exome sequencing (WES) was used. Immunologic characteristics of patients were evaluated using flow cytometry, nephelometry, and conventional blood counts. The current study is conducted at Tehran’s Children Medical Center and is approved by the ethics committee of Tehran University of Medical Sciences.&#x0D; Results: Between March 2013 and October 2019, we enrolled 30 patients with LRBA-deficiency and 13 patients with CVID, who had no identified genetic mutations. Regarding clinical features, there were no significant differences for the prevalence of infections at different sites (lung, sinuses, and middle ear) among the two groups (all P-values &gt; 0.05). However, the incidences of autoimmune disorders and enteropathy were significantly higher among LRBA-deficient cases (P &lt; 0.001). In serum levels of immunoglobulins, there were significant differences for IgG and IgM between the two groups (P-values of 0.014 and 0.004, respectively); however, this was not seen for IgA and IgE levels. Likewise, we did not see any significant differences for the cluster of differentiation (CD) markers between the two groups (all P-values &gt; 0.05).&#x0D; Conclusion: Compared to the CVID patients with no identified genetic mutations, LRBA-deficient patients have a significantly greater chance of parental consanguinity and developing autoimmune disorders and enteropathy, and have significantly higher values of serum IgG and IgM. The rate of infectious complications and other basic laboratory features, do not show significant differences between the two groups.

Various phenotypes of LRBA gene with compound heterozygous variation: A case series report of pediatric cytopenia patients.

Objective:LPS-responsive beige-like anchor (LRBA) deficiency is one of the most common monogenic disorders causing common variable immunodeficiency (CVID) and CVID-like disorders. However, the clinical spectrum of compound heterozygous (CHZ) LRBA variation should be extended. In this study, we presented five cases of compound heterozygous LRBA with various refractory cytopenias.Materials and Methods:Retrospective analysis of the clinical manifestations, management, and outcomes of five cases (from five pedigrees) with LRBA gene CHZ variants which initially manifested as single/multilineage immune cytopenias was performed. Results: 1. Gene variations: All five patients inherited the compound heterozygous LRBA variations from their parents which were thought to be pathogenic. BEACH, DUF4704, and LamG were the main affected domains of LRBA gene in this case series. 2. Immune dysregulation of clinic: (1) Hypogammaglobulinemia were recorded in four patients, and the proportion of Treg was decreased in two patients. Only one patient had been with increased TCRαβ+CD4/CD8 double-negative T cells (DNT). (2) Lymphoproliferative manifestations were seen in three patients. (3) All five patients were complained with cytopenia, although they showed different clinical manifestations. None of the parents was asymptomatic. (4) Other immune disorders: P5 also had relapsed infections and autoimmune endocrinopathy. 3. Management and outcomes: P1 and P5 responded well to immunomodulatory therapy and P3 was effectively treated with hemophagocytic lymphohistiocytosis (HLH) first-line regimen chemotherapy. P4 showed no responses to steroids and IVIG. However, TPO-R agonist was effective.Conclusion:Unlike homozygous mutations, compound heterozygous LRBA variation should always be kept in mind for the various phenotypes and different treatment responses.