Background: Among the red cell membrane disorders, hereditary spherocytosis (HS) is one of the most common causes of inherited hemolytic anemia. The aim of this study was to compare the flow-cytometric approach for screening of red cell membrane disorders based on osmotic fragility with the eosin-5-maleimide (E5 0 M) dye test. A group of b-thalassemia heterozygotes were also studied.Methods: A red cell suspension was spiked with deionized water during acquisition and the count of residual red cells measured sequentially in real-time using flow cytometry. Fluorescence intensity of red cells stained with eosin-5-maleimide was also measured.Results: The hereditary spherocytosis (HS) group showed significantly decreased percentage residual red cells (9.31% 6 3.75%) (P 5 0.0091) whereas the b-thalassemia group showed a significant increase (93.56% 6 12.98%) (P 5 0.0008) compared to the normal control group (46.26% 6 11.33%). The cut off value of the flow cytometric osmotic fragility (FCM OF) test for red cell membrane disorders was 23.59% giving a sensitivity of 100% and specificity of 98%.Conclusions: The advantages of the FCM OF test are that it is quantitative, time effective and requires only deionized water for the measurement of osmotic fragility. It could be an effective first line screening approach for red cell membrane disorders in hematology laboratories where a flow cytometer is available.

Autoimmune lymphoproliferative syndrome (ALPS) is a disorder of lymphocyte homeostasis. It is characterized by non‐malignant lymphoproliferation autoimmunity mostly directed toward blood cells and increased risk of lymphoma. Majority of patients with ALPS harbor heterozygous germline mutations in the gene for the TNF receptor‐family member Fas (CD 95, Apo‐1) which are inherited in an autosomal dominant fashion. Somatic Fas mutations are the second most common genetic etiology of ALPS. Additionally mutations in the genes encoding Fas‐ligand (FASLG), caspase 10 (CASP10) and caspase 8 (CASP8), NRAS and KRAS have been identified in a small number of patients with ALPS and related disorders. Approximately one‐third of patients with ALPS have yet unidentified defect. ALPS was initially thought to be a very rare disease, but recent studies have shown that it may be more common than previously thought. Testing for ALPS should therefore be considered in patients with unexplained lymphadenopathy, cytopenias, and hepatosplenomegaly. There have been significant advances in the understanding of the pathophysiology of ALPS in last few years which has resulted in the development of new diagnostic criteria and a number of targeted therapies. This review describes the clinical and laboratory manifestations found in patients with ALPS, as well as the molecular basis for the disease and new advances in treatment.

B cell expansion with NF-κB and T cell anergy (BENTA) is a rare primary immunodeficiency disorder caused by mutations in the CARD11 gene and results in constitutive NF-κB activation in B and T cells. Affected patients present with polyclonal expansion of B cells at an early age with splenomegaly, lymphadenopathy, and mild autoimmunity. Here, we discuss four BENTA cases with unusual clinical manifestations not previously reported. All patients showed previously reported gain-of-function mutations (G123S, G123D, and C49Y) in the CARD11 gene. Severe autoimmune manifestations were noted for the first time in all our patients.

Severe combined immunodeficiency (SCID) represents one of the most severe forms of primary immunodeficiency (PID) disorders characterized by impaired cellular and humoral immune responses. Here, we report the clinical, immunological, and molecular findings in 57 patients diagnosed with SCID from India. Majority of our patients (89%) presented within 6 months of age. The most common clinical manifestations observed were recurrent pneumonia (66%), failure to thrive (60%), chronic diarrhea (35%), gastrointestinal infection (21%), and oral candidiasis (21%). Hematopoietic Stem Cell Transplantation (HSCT) is the only curative therapy available for treating these patients. Four patients underwent HSCT in our cohort but had a poor survival outcome. Lymphopenia (absolute lymphocyte counts/μL <2,500) was noted in 63% of the patients. Based on immunophenotypic pattern, majority of the cases were T−B− SCID (39%) followed by T−B+ SCID (28%). MHC class II deficiency accounted for 10.5% of our patient group. A total of 49 patients were molecularly characterized in this study and 32 novel variants were identified in our cohort. The spectrum of genetic defects in our cohort revealed a wide genetic heterogeneity with the major genetic cause being RAG1/2 gene defect (n = 12) followed by IL2RG (n = 9) and JAK3 defects (n = 9). Rare forms of SCID like Purine nucleoside phosphorylase (PNP) deficiency, reticular dysgenesis, DNA-Protein Kinase (DNA-PKcs) deficiency, six cases of MHC class II deficiency and two ZAP70 deficiency were also identified in our cohort. Fourteen percent of the defects still remained uncharacterized despite the application of next generation sequencing. With the exception of MHC class II deficiency and ZAP70 deficiency, all SCID patients had extremely low T cell receptor excision (TRECs) (<18 copies/μL).

Leukocyte adhesion deficiency (LAD) syndrome is a group of inborn errors of immunity characterized by a defect in the cascade of the activation and adhesion leading to the failure of leukocyte to migrate to the site of tissue injury. Three different types of LAD have been described. The most common subtype is LAD type 1 (LAD1) caused due to defects in the ITGβ2 gene. LAD type 2 (LAD2) is caused by mutations in the SLC35C1 gene leading to a generalized loss of expression of fucosylated glycans on the cell surface and LAD type 3 (LAD3) is caused by mutations in the FERMT3 gene resulting in platelet function defects along with immunodeficiency. There is a paucity of data available from India on LAD syndromes. The present study is a retrospective analysis of patients with LAD collated from 28 different centers across India. For LAD1, the diagnosis was based on clinical features and flow cytometric expression of CD18 on peripheral blood leukocytes and molecular confirmation by Sanger sequencing. For patients with LAD3 diagnosis was largely based on clinical manifestations and identification of the pathogenic mutation in the FERMT3 gene by next-generation Sequencing. Of the total 132 cases diagnosed with LAD, 127 were LAD1 and 5 were LAD3. The majority of our patients (83%) had CD18 expression less than 2% on neutrophils (LAD1°) and presented within the first three months of life with omphalitis, skin and soft tissue infections, delayed umbilical cord detachment, otitis media, and sepsis. The patients with CD18 expression of more than 30% (LAD1+) presented later in life with skin ulcers being the commonest manifestation. Bleeding manifestations were common in patients with LAD3. Persistent neutrophilic leukocytosis was the characteristic finding in all patients. 35 novel mutations were detected in the ITGβ2 gene, and 4 novel mutations were detected in the FERMT3 gene. The study thus presents one of the largest cohorts of patients from India with LAD, focusing on clinical features, immunological characteristics, and molecular spectrum.

Paroxysmal nocturnal haemoglobinuria (PNH) is a rare acquired clonal disorder of haematopoietic stem cells. The molecular defect in PNH is mutation in the phosphotidylinositol glycan complementation class A (PIGA gene) causing defect in glycosylphosphatidylinositol anchored proteins (Cell, 73, 1993, 703). The deficiency of these GPI‐anchored proteins on the membranes of haematopoietic cells lead to the various clinical manifestations of PNH. Clinically PNH is classified into classic PNH, PNH in the setting of another specified bone marrow disorder and sub clinical PNH. Size of the PNH clone differs in these different subtypes. The management of PNH has been revolutionized by the advent of monoclonal antibody, eculizumab. Thus, today it is important to have sensitive tests to diagnose and monitor the clone size in patients of PNH. Before 1990, diagnosis of PNH was made using complement based tests. However in the last decade, flowcytometry has become the gold standard diagnostic test as it has increased sensitivity to detect small clones, ability to measure clone size and is not affected by blood transfusions. This review is aimed to focus mainly on the different methods available for the detection of PNH clone and the recent advances and recommendations for the flowcytometric diagnosis of PNH.

Primary immunodeficiency diseases (PID) are a clinically and immunologically heterogeneous group of disorders of immune system. Diagnosis of these disorders is often challenging and requires identification of underlying genetic defects, complemented by a comprehensive evaluation of immune system. Flow cytometry, with its advances in the last few decades, has emerged as an indispensable tool for enumeration as well as characterization of immune cells. Flow cytometric evaluation of the immune system not only provides clues to underlying genetic defects in certain PIDs and helps in functional validation of novel genetic defects, but is also useful in monitoring immune responses following specific therapies. India has witnessed significant progress in the field of flow cytometry as well as PID over last one decade. Currently, there are seven Federation of Primary Immunodeficiency Diseases (FPID) recognized centers across India, including two Indian Council of Medical research (ICMR) funded centers of excellence for diagnosis, and management of PIDs. These centers offer comprehensive care for PIDs including flow cytometry based evaluation. The key question which always remains is how one selects from the wide array of flow cytometry based tests available, and whether all these tests should be performed before or after the identification of genetic defects. This becomes crucial, especially when resources are limited and patients have to pay for the investigations. In this review, we will share some of our experiences based on evaluation of a large cohort of hemophagocytic lymphohistiocytosis, severe combined immunodeficiency, and chronic granulomatous disease, and the lessons learned for optimum use of this powerful technology for diagnosis of these disorders.

Pyoderma gangrenosum (PG) is an uncommon noninfectious neutrophilic dermatosis characterized by recurrent, sterile, necrotic skin ulcers. It is commonly associated with underlying systemic disease like inflammatory bowel disease, rheumatoid arthritis and hematological malignancies. Pathogenesis of PG remains unclear though aberrant immune responses have been implicated. The diagnosis of PG is of exclusion and management is empirical with local or systemic immunosuppressive therapy. LAD-I is a rare form of autosomal recessive disorders caused by mutations of the gene ITGB2, clinically characterized by recurrent severe bacterial infection, impaired pus formation, poor wound healing and persistent neutrophilia. Though skin ulcerations are common, predominant clinical presentation as PG is unusual in LAD-I. Here we present four Indian patients with LAD-I from three unrelated families initially diagnosed as PG due to chronic recurrent skin ulcerations requiring steroids and antibiotics for healing, associated with atrophic scar formation. All these four patients had persistent neutrophilia without history of delayed cord separation and showed moderate expression of CD18 (19 to 68%) on neutrophils. Sequencing of the entire coding region and intronic splice sites of the ITGB2 gene from the genomic DNA of these patients revealed a novel common mutation IVS10+4A>G. LAD-I should be kept in mind while evaluating patients with PG especially those with persistent neutrophila in the absence of other rheumatological disorders. Diagnosis of LAD-I in these cases is extremely important for management as treating these patients without adequate antibiotic cover may prove fatal and these patients often require hematopoietic stem cell transplantation for permanent cure.