Wiskott-Aldrich syndrome protein expression in female WAS carriers: A flow cytometry study from North India

INTRODUCTION

Wiskott-Aldrich syndrome (WAS) is a rare X-linked inborn error of immunity characterized by microthrombocytopenia, infections, eczema, and increased predisposition to develop autoimmunity and malignancy. Flow cytometric assay for determining WAS protein (WASp) is a rapid and cost-effective tool for detecting patients. However, very few studies described WASp expression in female carriers. Most WAS carriers are clinically asymptomatic. Active screening of female family members helps identify female carriers, distinguish de novo mutations, and to select appropriate donor prior to curative stem cell transplantation. This study was undertaken to evaluate the diagnostic capability of flow cytometry-based WASp expression in peripheral blood cells to identify carriers and compare WASp expression in different blood cell lineages.

PATIENTS AND METHODS

Female patients, heterozygous for WAS gene, were enrolled in this study conducted at Pediatric Allergy Immunology Unit, Advanced Pediatric Centre, Post Graduate Institute of Medical Education and Research, Chandigarh, India. Flow cytometric assessment of WASp expression in lymphocytes, monocytes, and neutrophils was carried out and compared with healthy control and affected patients. The results were expressed in delta (Δ) median fluorescence intensity (MFI) as well as stain index (SI), which is the ratio of ΔMFI of patient and ΔMFI of control.

RESULTS

Thirteen mothers and two sisters of genetically confirmed WAS patients were enrolled in the study. All enrolled females were clinically asymptomatic and did not have microthrombocytopenia. Low WASp expression (SI < 1) was seen in lymphocytes and monocytes in 10 (66.6%) carriers. Females with variants in proximal exons (exons 1 and 2) were found to have lesser expression than those with distal (exons 3-12) variants.

CONCLUSION

Flow cytometry is a rapid, easily available, cost-effective tool for WASp estimation. Lymphocytes followed by monocytes are the best cell lineages for WASp estimation in carrier females. However, genetic testing remains the gold standard, as carrier females with variants in distal exons may have normal WASp expression.

X-Linked Lymphoproliferative Syndrome: A Spectrum of Clinical and Immunological Profile and Novel Pathogenic Variants from Chandigarh, India

INTRODUCTION

X-linked lymphoproliferative syndrome (XLP) is a rare primary immune deficiency. Two types of XLP have been described: XLP-1 and XLP-2.

METHODS

We found 7 patients with XLP (3 had XLP-1 and 4 had XLP-2) after reviewing the data from Pediatric Immunodeficiency Clinic from 1997 to 2021.

RESULTS

Mean age at diagnosis was 3.8 years, and mean delay in diagnosis was 2.6 years. Five patients had recurrent episodes of infections. Four patients developed at least one episode of hemophagocytic lymphohistiocytosis (HLH) (2 with XLP-1 and 2 with XLP-2). Of these, 2 had recurrent HLH (both with XLP-2). Epstein-Barr virus (EBV) infection was detected in 2 (1 with XLP-1 and 1 with XLP-2). Both these patients had HLH. One child with XLP-2 had inflammatory bowel disease. Hypogammaglobulinemia was seen in 3 (2 with XLP-1 and 1 with XLP-2). Genetic analysis showed previously reported variants in 5, while 2 had novel variants (one in exon 7 of XIAP gene [c.1370dup p.Asn457Lysfs Ter16] and other had splice site variant in intron 1 of SH2D1A gene [c.138-2_138-1insG]). Episodes of HLH were managed with intravenous immunoglobulin (IVIg), methylprednisolone, oral prednisolone, cyclosporine, and rituximab. Inflammatory bowel disease was managed using oral prednisolone and azathioprine. One patient underwent haploidentical hematopoietic stem cell transplantation. One child with XLP-2 and WAS died because of fulminant pneumonia.

DISCUSSION/CONCLUSIONS

XLP should be considered as a strong possibility in any patient with features of HLH, repeated infections with hypogammaglobulinemia, persistent EBV infection, and early-onset IBD.

CD40 gene polymorphism and its expression in children with Kawasaki disease from North India: a preliminary case-control study and meta-analysis

Introduction

CD40 gene single-nucleotide polymorphisms (SNPs) have been associated with susceptibility and development of coronary artery abnormalities (CAAs) in children with Kawasaki disease (KD) in Japanese, Chinese, and Taiwanese populations. However, data on SNPs of the CD40 gene in patients with KD from the Indian subcontinent are not available. We studied the CD40 gene polymorphisms and its expression in children with KD from North India.

Methods

SNPs of the CD40 gene (rs4810485, rs1535045) were studied using Sanger sequencing. CD40 expression was studied by flow cytometry. Meta-analysis was carried out to assess the role of both SNPs of the CD40 gene in KD. GRADEpro GDT software (v.3.2) was used to assess the "certainty of evidence."

Results

Forty-one patients with KD and 41 age-, sex-matched febrile controls were enrolled. However, none of the alleles and genotypes of the CD40 gene were found to be associated with KD. CD40 expression was higher in KD and in KD with CAAs compared to controls, but it failed to reach statistical significance. In a meta-analysis, the T allele of rs153045 was found to be significantly associated with KD (OR = 1.28; 95% confidence interval (: 1.09-1.50; p = 0.002). The GRADE of evidence for this outcome, however, is of " very low certainty."

Conclusion

The present study found no association between SNPs (rs4810485 and rs153045) and susceptibility to KD. This could be a reflection of a modest sample size. CD40 expression was higher in KD and in KD with CAAs. In the meta-analysis, the T allele of rs153045 was significantly associated with KD. Our study confirms a significant genetic heterogeneity in KD among different ethnicities.

Blau syndrome: Lessons learned in a tertiary care centre at Chandigarh, North India

Objectives

Blau syndrome (BS) is a rare autoinflammatory disease characterized by arthritis, dermatitis, and granulomatous uveitis in early childhood. The study presents the clinical experience of patients with BS at a tertiary care centre in Chandigarh, North India.

Methods

Analysis of the clinical profile of patients of BS with NOD2 gene mutations under follow-up was carried out.

Results

Diagnosis of BS was genetically confirmed in 11 patients (10 children and one adult; six male and five female patients) from 10 families. The median age of onset of symptoms was 12 months (range, 4 months–4 years), while the age at diagnosis ranged from 2.3 to 26 years. The classic triad of arthritis, dermatitis, and uveitis was present in 6/11 (54.5%) patients. The frequency of arthritis, dermatitis, and uveitis was 100%, 81.8%, and 72.7%, respectively. The median age at diagnosis of ocular symptoms was 4 years (range, 2–26 years). Family history was noted in six families. Renal involvement was observed in two children. All patients in our cohort had the R334W variant in NOD2 gene. An asymptomatic carrier sibling with R334W mutation was identified in one family. Methotrexate was used as a first-line agent in all children. Adalimumab, which was commenced in five patients with uveitis, resulted in significant improvement in four patients. The total follow-up duration of the present cohort is 1,063.8 patient-months.

Conclusions

The possibility of BS should always be considered in patients with arthritis and early ocular involvement. Uveitis is often progressive and refractory to currently available therapies. Systemic involvement appears to remain a significant cause of morbidity and mortality.

An Autopsy Case of Wiskott-Aldrich Syndrome Revealing "FDC-Only Lymphoid Follicles" in Lymphoid Tissue: A Morphologic Correlate of Defective Immune Synapse

Wiskott-Aldrich Syndrome (WAS) is an inherited disorder characterized by the classical triad of eczema, micro-thrombocytopenia, and immune deficiency. This disease affects the hematopoietic cells to a variable extent. The spectrum of clinical and laboratory data for WAS has been well described in the literature though there is a paucity of its histopathologic and immunohistochemical correlates. The current case describes the autopsy findings of this rare entity in an 8-year old male child with specific recognition of altered histology noticed in the lymphoreticular tissues. The predominant morphological finding in lymphoid tissue was atretic hyalinized germinal centers labeled as "the follicular dendritic cell (FDC)-only lymphoid follicles." Immunohistochemistry revealed a reduction in germinal-center B-cells, T-follicular helper cells, attenuated mantle zone, FDC proliferation, and paracortical plasmacytosis. This case highlights the crippled immune cell population in WAS, ultimately leading to the morphology of atretic follicles rich in FDCs.

Autoimmunity in Wiskott-Aldrich Syndrome: Updated Perspectives

Wiskott–Aldrich syndrome (WAS) is an uncommon X-linked combined-immunodeficiency disorder characterized by a triad of thrombocytopenia, eczema, and immunodeficiency. Patients with WAS are also predisposed to autoimmunity and malignancy. Autoimmune manifestations have been reported in 26%–72% of patients with WAS. Autoimmunity is an independent predictor of poor prognosis and predisposes to malignancy. Development of autoimmunity is also an early pointer of the need for hematopoietic stem–cell transplantation. In this manuscript, we have collated the published data and present a narrative review on autoimmune manifestations in WAS. A summary of currently proposed immunopathogenic mechanisms and genetic variants associated with development of autoimmunity in WAS is also included.

Wiskott Aldrich Syndrome: A Multi-Institutional Experience From India

Background

Wiskott Aldrich syndrome (WAS) is characterized by bleeding manifestations, recurrent infections, eczema, autoimmunity, and malignancy. Over the last decade, improved awareness and better in-house diagnostic facilities at several centers in India has resulted in increased recognition of WAS. This study reports collated data across major primary immunodeficiency diseases (PID) centers in India that are involved in care of children with WAS and highlights the varied clinical presentations, genetic profile, and outcomes of patients in India.

Methods

Request to share data was sent to multiple centers in India that are involved in care and management of patients with PID. Six centers provided requisite data that were compiled and analyzed.

Results

In this multi-institutional cohort, clinical details of 108 patients who had a provisional diagnosis of WAS were received. Of these, 95 patients with 'definite WAS' were included Fourteen patients were classified as XLT and 81 patients as WAS. Median age at onset of symptoms of patients was 3 months (IQR 1.6, 6.0 months) and median age at diagnosis was 12 months (IQR 6,48 months). Clinical profile included bleeding episodes (92.6%), infections (84.2%), eczema (78.9%), various autoimmune manifestations (40%), and malignancy (2.1%). DNA analysis revealed 47 variants in 67 cases. Nonsense and missense variants were the most common (28.4% each), followed by small deletions (19.4%), and splice site defects (16.4%). We also report 24 novel variants, most of these being frameshift and nonsense mutations resulting in premature termination of protein synthesis. Prophylactic intravenous immunoglobulin (IVIg) was initiated in 52 patients (54.7%). Hematopoietic stem cell transplantation (HSCT) was carried out in 25 patients (26.3%). Of those transplanted, disease-free survival was seen in 15 patients (60%). Transplant related mortality was 36%. Outcome details were available for 89 patients. Of these, 37% had died till the time of this analysis. Median duration of follow-up was 36 months (range 2 weeks- 12 years; IQR 16.2 months- 70 months).

Conclusions

We report the first nationwide cohort of patients with WAS from India. Bleeding episodes and infections are common manifestations. Mortality continues to be high as curative therapy is not accessible to most of our patients.

Flow Cytometry for Diagnosis of Primary Immune Deficiencies-A Tertiary Center Experience From North India

Flow cytometry has emerged as a useful technology that has facilitated our understanding of the human immune system. Primary immune deficiency disorders (PIDDs) are a heterogeneous group of inherited disorders affecting the immune system. More than 350 genes causing various PIDDs have been identified. While the initial suspicion and recognition of PIDDs is clinical, laboratory tools such as flow cytometry and genetic sequencing are essential for confirmation and categorization. Genetic sequencing, however, are prohibitively expensive and not readily available in resource constrained settings. Flow cytometry remains a simple, yet powerful, tool for multi-parametric analysis of cells. While it is confirmatory of diagnosis in certain conditions, in others it helps in narrowing the list of putative genes to be analyzed. The utility of flow cytometry in diagnosis of PIDDs can be divided into four major categories: (a) Enumeration of lymphocyte subsets in peripheral blood. (b) Detection of intracellular signaling molecules, transcription factors, and cytokines. (c) Functional assessment of adaptive and innate immune cells (e.g., T cell function in severe combined immune deficiency and natural killer cell function in familial hemophagocytic lymphohistiocytosis). (d) Evaluation of normal biological processes (e.g., class switching in B cells by B cell immunophenotyping). This review focuses on use of flow cytometry in disease-specific diagnosis of PIDDs in the context of a developing country.