Pathogenic Gene Mutations or Variants Identified by Targeted Gene Sequencing in Adults With Hemophagocytic Lymphohistiocytosis

Into the storm: the imbalance in the yin-yang immune response as the commonality of cytokine storm syndromes

There is a continuous cycle of activation and contraction in the immune response against pathogens and other threats to human health in life. This intrinsic yin-yang of the immune response ensures that inflammatory processes can be appropriately controlled once that threat has been resolved, preventing unnecessary tissue and organ damage. Various factors may contribute to a state of perpetual immune activation, leading to a failure to undergo immune contraction and development of cytokine storm syndromes. A literature review was performed to consider how the trajectory of the immune response in certain individuals leads to cytokine storm, hyperinflammation, and multiorgan damage seen in cytokine storm syndromes. The goal of this review is to evaluate how underlying factors contribute to cytokine storm syndromes, as well as the symptomatology, pathology, and long-term implications of these conditions. Although the recognition of cytokine storm syndromes allows for universal treatment with steroids, this therapy shows limitations for symptom resolution and survival. By identifying cytokine storm syndromes as a continuum of disease, this will allow for a thorough evaluation of disease pathogenesis, consideration of targeted therapies, and eventual restoration of the balance in the yin-yang immune response.

Somatic mutations in FAS pathway increase hemophagocytic lymphohistiocytosis risk in patients with T- and/or NK-cell lymphoma

ABSTRACT

Although significant progress has been made in understanding the genetic basis of primary hemophagocytic lymphohistiocytosis (HLH), the pathogenesis of secondary HLH, the more prevalent form, remains unclear. Among the various conditions giving rise to secondary HLH, HLH in patients with lymphoma (HLH-L) accounts for a substantial proportion. In this study, we investigated the role of somatic mutations in the pathogenesis of HLH-L in a cohort of patients with T- and/or natural killer-cell lymphoma. We identified a 3-time higher frequency of mutations in FAS pathway in patients with HLH-L. Patients harboring these mutations had a 5-time increased HLH-L risk. These mutations were independently associated with inferior outcome. Hence, our study demonstrates the association between somatic mutations in FAS pathway and HLH-L. Further studies are warranted on the mechanistic role of these mutations in HLH-L.

Hemophagocytic Lymphohistiocytosis in Adolescents and Young Adults: Genetic Predisposition and Secondary Disease

Hemophagocytic lymphohistiocytosis (HLH) is a disorder of impaired immune regulation resulting in hyperinflammation that is ultimately fatal if not treated. HLH is categorized into familial disease, caused by genetic mutations affecting the function of cytotoxic T lymphocytes and natural killer cells, and secondary disease, triggered by infections, malignancies, rheumatologic disorders, or immune deficiency. Adolescent and young adults with HLH represent a unique population with specific diagnostic challenges. Here we review the diagnostic criteria, possible etiologies, pathophysiology, and management of HLH with focus on the adolescent population.

Severe adult hemophagocytic lymphohistiocytosis (HLHa) correlates with HLH-related gene variants

BACKGROUND

The contribution of genetic factors to the severity of adult hemophagocytic lymphohistiocytosis (HLHa) remains unclear.

OBJECTIVE

We sought to assess a potential link between HLHa outcomes and HLH-related gene variants.

METHODS

Clinical characteristics of 130 HLHa patients (age ≥ 18 years and HScore ≥ 169) and genotype of 8 HLH-related genes (LYST, PRF1, UNC13-D, STX11, STXBP2, RAB27A, XIAP, and SAP) were collected. A total of 34 variants found in only 6 genes were selected on the basis of their frequency and criteria predicted to impair protein function. Severity was defined by refractory disease to HLH treatment, death, or transfer to an intensive care unit.

RESULTS

HLHa-associated diseases (ADs) were neoplasia (n = 49 [37.7%]), autoimmune/inflammatory disease (n = 33 [25.4%]), or idiopathic when no AD was identified (n = 48 [36.9%]). Infectious events occurred in 76 (58.5%) patients and were equally distributed in all ADs. Severe and refractory HLHa were observed in 80 (61.5%) and 64 (49.2%) patients, respectively. HScore, age, sex ratio, AD, and infectious events showed no significant association with HLHa severity. Variants were identified in 71 alleles and were present in 56 (43.1%) patients. They were distributed as follows: 44 (34.4%), 9 (6.9%), and 3 (2.3%) patients carrying 1, 2, and 3 variant alleles, respectively. In a logistic regression model, only the number of variants was significantly associated with HLHa severity (1 vs 0: 3.86 [1.73-9.14], P = .0008; 2-3 vs 0: 29.4 [3.62-3810], P = .0002) and refractoriness (1 vs 0: 2.47 [1.17-5.34], P = .018; 2-3 vs 0: 13.2 [2.91-126.8], P = .0003).

CONCLUSIONS

HLH-related gene variants may be key components to the severity and refractoriness of HLHa.

Hemophagocytic lymphohistiocytosis with a hemizygous PRF1 c.674G>A mutation

Hemophagocytic lymphohistiocytosis(HLH) is a rare highly-fatal disease presenting with fever, hepatosplenomegaly, and pancytopenia and has a poor prognosis. Homozygous or semi-zygous or complex heterozygous variants can cause familial HLH and heterozygous carriers are frequently seen in secondary HLH. A 42-year-old male patient was admitted to the hospital for persistent fever, fatigue, and splenomegaly. Investigations revealed hypertriglyceridemia, hyperlactatemia dehydrogenaseemia, hyperferritinemia, and elevated levels of soluble cluster of differentiation 25. We found a heterozygous mutation of PRF1: c.674G>A (p.R225Q) through next-generation sequencing technology of hemophagocytic-lymphohistiocytosis-related genes. After a brief remission with dexamethasone and etoposide-based therapy, the disease relapsed quickly, and an allogeneic hematopoietic stem cell transplant was performed to achieve complete remission. To date, the patient's condition was in complete remission. Our study detected a rare missense mutation in the PRF1 gene in a patient with HLH disease and the c.674G>A mutation may be rated as a possible pathogenic variant.

Outcome of patients with primary and secondary hemophagocytic lymphohistiocytosis: A retrospective analysis from a tertiary care center

Hemophagocytic lymphohistiocytosis (HLH) is a progressive and potentially life-threatening disorder. It is classified into primary and secondary HLH. The objective of our study was to determine the outcome of primary and secondary HLH in pediatric and adult patients based on HScore and treatment modality. We conducted a retrospective analysis done from July 2010 to June 2020. Variables analyzed included age, gender and history of death in siblings. HScore was used for disease classification while clinical and laboratory findings which were required to fulfill the HScore diagnostic criteria were also recorded. Continuous variables were summarized as median and categorical variables as frequencies and percentages. Categorical variables were compared using chi-square test and Fisher Exact test. Significance of different variables between primary and secondary HLH was calculated using independent-samples t test. A P value of < .05 was taken as significant. A total of 51 patients were included in the analysis (41 in primary and 10 in secondary HLH group). In primary HLH, 36 patients were in the pediatric age group and 12.2% had a history of death in sibling. All 41 patients had increased ferritin and decreased fibrinogen levels. The overall survival in primary HLH was 44%. In the secondary HLH group, viral infections were the most common etiology and ferritin was increased as well. The overall survival in secondary HLH was 60%. The median survival was 15 ± 4.8 months. The overall survival of both groups combined was 53%. Primary HLH should be considered in pediatric patients who present with pancytopenia and hepatosplenomegaly. In centers where genetic testing is not available, HScore along with serum ferritin and fibrinogen is a good substitute for disease classification.

The 2022 EULAR/ACR Points to Consider at the Early Stages of Diagnosis and Management of Suspected Haemophagocytic Lymphohistiocytosis/Macrophage Activation Syndrome (HLH/MAS)

OBJECTIVE

Haemophagocytic lymphohistiocytosis (HLH) and macrophage activation syndrome (MAS) are life-threatening systemic hyperinflammatory syndromes that can develop in most inflammatory contexts. They can progress rapidly, and early identification and management are critical for preventing organ failure and mortality. This effort aimed to develop evidence-based and consensus-based points to consider to assist clinicians in optimising decision-making in the early stages of diagnosis, treatment and monitoring of HLH/MAS.

METHODS

A multinational, multidisciplinary task force of physician experts, including adult and paediatric rheumatologists, haematologist/oncologists, immunologists, infectious disease specialists, intensivists, allied healthcare professionals and patients/parents, formulated relevant research questions and conducted a systematic literature review (SLR). Delphi methodology, informed by SLR results and questionnaires of experts, was used to generate statements aimed at assisting early decision-making and optimising the initial care of patients with HLH/MAS.

RESULTS

The task force developed 6 overarching statements and 24 specific points to consider relevant to early recognition of HLH/MAS, diagnostic approaches, initial management and monitoring of HLH/MAS. Major themes included the simultaneous need for prompt syndrome recognition, systematic evaluation of underlying contributors, early intervention targeting both hyperinflammation and likely contributors, careful monitoring for progression/complications and expert multidisciplinary assistance.

CONCLUSION

These 2022 EULAR/American College of Rheumatology points to consider provide up-to-date guidance, based on the best available published data and expert opinion. They are meant to help guide the initial evaluation, management and monitoring of patients with HLH/MAS in order to halt disease progression and prevent life-threatening immunopathology.

The 2022 EULAR/ACR points to consider at the early stages of diagnosis and management of suspected haemophagocytic lymphohistiocytosis/macrophage activation syndrome (HLH/MAS)

OBJECTIVE

Haemophagocytic lymphohistiocytosis (HLH) and macrophage activation syndrome (MAS) are life-threatening systemic hyperinflammatory syndromes that can develop in most inflammatory contexts. They can progress rapidly, and early identification and management are critical for preventing organ failure and mortality. This effort aimed to develop evidence-based and consensus-based points to consider to assist clinicians in optimising decision-making in the early stages of diagnosis, treatment and monitoring of HLH/MAS.

METHODS

A multinational, multidisciplinary task force of physician experts, including adult and paediatric rheumatologists, haematologist/oncologists, immunologists, infectious disease specialists, intensivists, allied healthcare professionals and patients/parents, formulated relevant research questions and conducted a systematic literature review (SLR). Delphi methodology, informed by SLR results and questionnaires of experts, was used to generate statements aimed at assisting early decision-making and optimising the initial care of patients with HLH/MAS.

RESULTS

The task force developed 6 overarching statements and 24 specific points to consider relevant to early recognition of HLH/MAS, diagnostic approaches, initial management and monitoring of HLH/MAS. Major themes included the simultaneous need for prompt syndrome recognition, systematic evaluation of underlying contributors, early intervention targeting both hyperinflammation and likely contributors, careful monitoring for progression/complications and expert multidisciplinary assistance.

CONCLUSION

These 2022 EULAR/American College of Rheumatology points to consider provide up-to-date guidance, based on the best available published data and expert opinion. They are meant to help guide the initial evaluation, management and monitoring of patients with HLH/MAS in order to halt disease progression and prevent life-threatening immunopathology.

The Clinical Significance and Prognostic Role of Whole-Blood Epstein-Barr Virus DNA in Lymphoma-Associated Hemophagocytic Lymphohistiocytosis

PURPOSE

To evaluate the role of circulating Epstein-Barr virus (EBV) DNA in lymphoma-associated hemophagocytic lymphohistiocytosis (HLH).

METHODS

We conducted a retrospective cohort study to explore the clinical and prognostic significance of EBV DNA in lymphoma-associated HLH. We included adult patients with combined diagnoses of lymphoma and HLH from January 2010 and November 2022 by retrieving the medical record system.

RESULTS

A total of 281 patients with lymphoma-associated HLH were identified. Elevated whole-blood EBV DNA was observed in 54.4% (153/281) of patients, and the median copy number was significantly higher in the T/NK-cell malignancies (199,500, interquartile range, 30,000-1,390,000) than that in the B-cell non-Hodgkin lymphoma (5520, interquartile range, 1240-28,400, P < 0.001). The optimum cutoff for predicting survival was 16,100 copies/mL. Compared to the patients with EBV DNA ≤ 16,100 copies/mL, those with EBV DNA > 16,100 copies/mL were younger and had more T/NK-cell malignancies, lower levels of neutrophils and fibrinogen, and higher levels of hemoglobin, alanine aminotransferase, aspartate aminotransferase, lactic dehydrogenase, and β₂-microglobulin. A higher load of EBV DNA (> 16,100 copies/mL), thrombocytopenia (< 100 × 10⁹/L), neutropenia (< 1 × 10⁹/L), hypofibrinogenemia (≤ 1.5 g/L), and elevated levels of creatinine (> 133 μmol/L) were independent adverse predictors of 60-day overall survival and overall survival. A prognostic index based on EBV DNA and the other four factors was established to categorize the patients into four groups with significantly different outcomes.

CONCLUSION

Our study identified high EBV load as a risk factor for lymphoma-associated HLH and established a prognostic index to predict outcomes.

A young woman with persistent sore throat, Epstein-Barr virus, lymphadenopathy, and aberrant CD4 + CD7- T-cells

A young woman with persistent EBV viremia and lymphocytosis had an abnormal CD4- T cell population with aberrant loss of CD7. She had a diagnosis of chronic active EBV (CAEBV), a lymphoproliferative disorder for which she ultimately required allogeneic hematopoietic stem cell transplantation.

Platelet and ferritin as early predictive factors for the development of macrophage activation syndrome in children with Kawasaki disease: A retrospective case-control study

OBJECTIVE

To investigate the early predictive factors for Kawasaki disease complicated with macrophage activation syndrome (KD-MAS).

METHODS

We performed a retrospective case-control study in children with KD from August 2017 to August 2022, involving 28 cases with KD-MAS and 112 cases not developing KD-MAS. Based on the univariate analysis, binary logistic regression was used to identify the early predictive factors for KD-MAS development, and the receiver operating characteristic curve (ROC) analysis was carried out to obtain the optimal cut-off value.

RESULTS

Two predictive factors were associated with the development of KD-MAS, which were PLT (OR = 1.013, 95%CI, 1.001-1.026), and serum ferritin (OR = 0.991, 95%CI, 0.982-0.999). The cut-off value of PLT was 110 × 10⁹/L, and the cut-off value of serum ferritin was 548.4 ng/ml.

CONCLUSION

Children with KD who had a PLT count under 110 × 10⁹/L, and a serum ferritin level over 548.4 ng/ml are more likely to develop KD-MAS.

"A Dangerous Black Box:" Idiopathic Hemophagocytic Lymphohistiocytosis in Adult Patients-A Case Report and Review of the Literature

Hemophagocytic lymphohistiocytosis (HLH) is a rare potentially life-threatening condition characterized by aberrant inflammation that can be related to genetic or sporadic forms. In both forms, triggering factors may be involved. Early detection of the underlying cause is crucial for therapeutic decision, while early intervention might be associated with better outcomes. The largest descriptions in the literature on HLH refer to pediatric cases. Adolescents and adults may also be affected, but there is scarce evidence regarding their diagnosis and management. We describe here the case of a 68-year-old Swiss woman with HLH, in whom an extensive search for underlying causes was performed, but neither trigger nor pathogenic variant was found. An early intervention first with dexamethasone and later with cyclosporine was performed. The patient showed a favorable response and did not require further hospitalization; however, one year after diagnosis, it was not possible to suspend cyclosporine due to recurrence of laboratory inflammation signs by drug tapering. The occurrence of HLH idiopathic forms represents a challenge; failure to identify the underlying triggering cause generates uncertainty, endless diagnostic investigations, and consequently additional delays in the treatment. This manuscript addresses the difficulties on this issue.

UNC13D inhibits STING signaling by attenuating its oligomerization on the endoplasmic reticulum

Stimulator of interferon genes (STING) is an essential signaling protein that is located on the endoplasmic reticulum (ER) and triggers the production of type I interferons (IFN) and proinflammatory cytokines in response to pathogenic DNA. Aberrant activation of STING is linked to autoimmune diseases. The mechanisms underlying homeostatic regulation of STING are unclear. Here, we report that UNC13D, which is associated with familial hemophagocytic lymphohistiocytosis (FHL3), is a negative regulator of the STING-mediated innate immune response. UNC13D colocalizes with STING on the ER and inhibits STING oligomerization. Cellular knockdown and knockout of UNC13D promote the production of interferon-β (IFN-β) induced by DNA viruses, but not RNA viruses. Moreover, UNC13D deficiency also increases the basal level of proinflammatory cytokines. These effects are diminished by an inhibitor of STING signaling. Furthermore, the domains involved in the UNC13D/STING interaction on both proteins are mapped. Our findings provide insight into the regulatory mechanism of STING, the previously unknown cellular function of UNC13D and the potential pathogenesis of FHL3.

Hemophagocytic Lymphohistiocytosis in Adults: A Retrospective Study in a Belgian Teaching Hospital

Introduction

Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening disease, which can be primary (due to genetic mutation) or secondary to malignancy, infection and rheumatologic diseases. Data concerning Belgian patients with adult HLH are lacking.

Methods

This retrospective study was performed in a teaching hospital in Belgium. All cases of adult HLH, from December 2010 to April 2022, were reviewed. Patients with more than five HLH-2004 criteria and/or HScore >80% were included in the study. The objective of our study was to describe clinical and biological characteristics of patients with HLH and attempt to look for variables associated with mortality.

Results

Fifty-two patients were included in the final analysis. Mean age (SD) of patients was 48 (18) years old, and 29 patients were of male gender (56%). The underlying diseases associated with HLH were malignancy (M-HLH) in 22 patients, infection related HLH in 20 patients, rheumatologic disease related HLH in 7 patients, idiopathic in 2 patients and secondary to pregnancy in 1 patient. Overall mortality, mortality at 30 days and 90 days were 24/52 (46%), 13/52 (25%) and 4/52 (10%), respectively. In univariate analysis, malignancy, male sex, age and disseminated intravascular coagulation (DIC) were associated with mortality (p < 0.05). In multivariate analysis, only age was significantly associated with mortality (odds ratio, 1.053; 95% confidence interval, 1.016–1.092; p 0.005).

Conclusion

In our study, the most frequent triggers were malignancy and infectious agent followed by rheumatologic disease. Risk factors for mortality were age, male sex, malignancy and DIC, but only age remained significant in multivariate analysis. Treatment guidelines are mainly based on pediatric patients, and it is important for physician to describe adult patients’ outcome to better understand this disease and adapt treatment.

Adult-Onset Familial Hemophagocytic Lymphohistiocytosis Presenting with Annular Erythema following COVID-19 Vaccination

Familial hemophagocytic lymphohistiocytosis (HLH) is a rare genetic and life-threatening immunodeficiency disease. Here, we present a 38-year-old male who initially developed multiple annular to irregular erythema accompanied by a fever after COVID-19 vaccination. He was diagnosed with HLH with evidence of leukocytopenia in a full blood test, elevations of ferritin and sCD25, decreased NK cell function, and hemophagocytosis of a bone marrow biopsy specimen. A genetic examination revealed two probable disease-causing heterozygous mutations on UNC13D associated with type 3 familial HLH. A review of the case reports relevant to HLH following COVID-19 vaccination and the cutaneous manifestations of HLH with genetic defects suggests the necessity that individuals with preexisting immune dysregulation or diseases not classified should be cautious about COVID-19 vaccination and reminds clinicians that various recalcitrant skin lesions may be a sign of HLH.

Spectrum and trigger identification of hemophagocytic lymphohistiocytosis in adults: A single-center analysis of 555 cases

Limited data are available about the underlying causes of hemophagocytic lymphohistiocytosis (HLH) in adults. We collected and analyzed the data of 555 cases of adult HLH. HLH in 242 patients were malignancies-related and lymphoid malignancies (42.0%, 233/555) were the most common causes. Aggressive natural killer-cell leukemia, diffuse large B-cell lymphoma, and extranodal natural killer/T-cell lymphoma, nasal type were the most common specified pathological subtypes. Epstein-Barr virus (EBV) (69.0%, 100/145) was the most common pathogen among the cases of infections-related HLH (26.1%, 145/555). Malignancies-related HLH showed male preponderance, more common splenomegaly, more severe anemia and thrombocytopenia, and significantly elevated soluble CD25. In patients with abnormal lymphoid cells in the bone marrow (BM) and increased EBV DNA copy number, 48.9% (45/92) of them were aggressive natural killer-cell leukemia. In patients with abnormal lymphoid cells in the BM and normal EBV DNA copy number, 66.2% (47/71) of them were B-cell non-Hodgkin lymphoma. In patients with elevated EBV DNA copy number but no abnormal lymphoid cells in the BM, 71.0% (98/138) of these cases were EBV infection. In conclusion, lymphoid malignancy is the most common underlying cause of adult HLH, followed by EBV infection. Based on the BM morphology and EBV load, we developed a diagnostic flow for rapid determination of the triggers for HLH.

Platelet-Related Molecular Subtype to Predict Prognosis in Hepatocellular Carcinoma

Purpose

Complex crosstalk between tumor cells and platelets is closely related to the development, relapse, and drug resistance of hepatocellular carcinoma (HCC). Therefore, an intensive analysis of the relationship between platelet-related genes and the effectiveness of immunotherapy is necessary for improving the poor prognosis of HCC patients.

Methods

Genes associated with platelets in the GeneCards database were collected and were used to identify molecular subtypes using a non-negative matrix decomposition algorithm (NMF) and constructed a platelet-related genes-based prognostic stratification model by the LASSO-Cox regression and stepwise Cox regression analysis. The effect of this feature on the immune microenvironment of HCC and the response to immune checkpoint inhibitors was also explored.

Results

After identifying two molecular subtypes, we constructed a platelet-related genes-based prognostic stratification model that can be effectively used for immune checkpoint inhibitor (PD1, PD-L1, PD-L2, and CTLA4) efficacy and prognosis prediction in HCC patients, which was subsequently validated using patient samples from ICGC, GSE14520 and a small sample size clinical cohort. We also found downregulation of PAFAH1B3 remarkably inhibited the proliferation and migration ability of Hep3B cells by cytological experiments.

Conclusion

We constructed a prognostic classifier based on platelet-related genes that could effectively classify HCC patients for prognostic prediction and provide new light on the selection of optimal individualized antiplatelet therapy for HCC patients in future clinical practice.

A Novel Prognostic Index Model for Adult Hemophagocytic Lymphohistiocytosis: A Multicenter Retrospective Analysis in China

Hemophagocytic lymphohistiocytosis (HLH) is an immune disorder with rapid progression and poor survival. Individual treatment strategy is restricted, due to the absence of precise stratification criteria. In this multicenter retrospective study, we aimed to develop a feasible prognostic model for adult HLH in China. A total of 270 newly diagnosed patients of adult HLH were retrieved from the Huaihai Lymphoma Working Group (HHLWG), of whom 184 from 5 medical centers served as derivation cohort, and 86 cases from 3 other centers served as validation cohort. X-Tile program and Maxstat analysis were used to identify optimal cutoff points of continuous variables; univariate and multivariate Cox analyses were used for variable selection, and the Kaplan–Meier curve was used to analyze the value of variables on prognosis. The C-index, Brier Score, and calibration curve were used for model validation. Multivariate analysis showed that age, creatinine, albumin, platelet, lymphocyte ratio, and alanine aminotransferase were independent prognostic factors. By rounding up the hazard ratios from 6 significant variables, a maximum of 9 points was assigned. The final scoring model of HHLWG-HPI was identified with four risk groups: low risk (≤3 pts), low-intermediate risk (4 pts), high-intermediate risk (5-6 pts), and high risk (≥7 pts), with 5-year overall survival rates of 68.5%, 35.2%, 21.3%, and 10.8%, respectively. The C-indexes were 0.796 and 0.758 in the derivation and validation cohorts by using a bootstrap resampling program. In conclusion, the HHLWG-HPI model provides a feasible and accurate stratification system for individualized treatment strategy in adult HLH.

Central nervous system involvement and thrombocytopenia as predictors of mortality in children with hemophagocytic lymphohistiocytosis

INTRODUCTION

Hemophagocytic lymphohistiocytosis (HLH) is a potentially life-threatening condition. This study aimed to evaluate treatment outcomes and identify prognostic-related factors in Thai children with HLH.

MATERIALS AND METHODS

We retrospectively reviewed the medical records of 76 pediatric patients with HLH who were treated at Ramathibodi Hospital between January 2004 and December 2019. Treatment outcomes were defined as early mortality (death within 30 days after diagnosis) and early treatment response (resolution of all clinical features and normalization of at least one HLH-related laboratory parameter within 4 weeks).

RESULTS

The overall mortality rate was 38% (29/76), with an early mortality rate of 45% (13/29). Malignancy-associated HLH had the highest mortality rate (88%), followed by primary HLH (56%). The predictors of early mortality were central nervous system (CNS) involvement [OR 13 (95%CI 2-83), p = 0.007] and platelet counts <44 × 10⁶/mm³ [OR 8 (95%CI 1.3-49), p = 0.024]. The predictors of early treatment response were no CNS involvement [OR 6.6 (95%CI 1.5-28.8), p = 0.011], platelet counts more than 44 × 10⁶/mm³ [OR 8 (95%CI 2.1-30.9), p = 0.003], and total bilirubin levels <1.8 mg/dL [OR 4 (95%CI 1.1-14.8), p = 0.036]. In the mixed-model analysis, platelet counts in non-survivors increased significantly less than those in survivors, with a mean difference in platelet changes between the two groups of 94.6 × 10⁶/mm³ (p = 0.003).

CONCLUSION

The independent predictors of early mortality in children with HLH were CNS involvement and low baseline platelet counts. A slow rate of platelet increases during the first week after diagnosis was also associated with mortality.

Digenic Inheritance: Evidence and Gaps in Hemophagocytic Lymphohistiocytosis

Hemophagocytic lymphohistiocytosis (HLH) is a hyperinflammatory disorder characterized by the inability to properly terminate an immune response. Familial HLH (FHLH) and related immune dysregulation syndromes are associated with mutations in the genes PRF1, UNC13D, STX11, STXBP2, LYST, AP3B1, and RAB27A, all of which are required for the assembly, exocytosis, and function of cytotoxic granules within CD8+ T cells and natural killer (NK) cells. Loss-of-function mutations in these genes render the cytotoxicity pathway ineffective, thereby failing to eradicate immune stimuli, such as infectious pathogens or malignant cells. The resulting persistent immune system stimulation drives hypercytokinemia, ultimately leading to severe tissue inflammation and end-organ damage. Traditionally, a diagnosis of FHLH requires the identification of biallelic loss-of-function mutations in one of these degranulation pathway genes. However, this narrow definition fails to encompass patients with other genetic mechanisms underlying degranulation pathway dysfunction. In particular, mounting clinical evidence supports a potential digenic mode of inheritance of FHLH in which single loss-of-function mutations in two different degranulation pathway genes cooperate to impair pathway activity. Here, we review the functions of the FHLH-associated genes within the degranulation pathway and summarize clinical evidence supporting a model in which cumulative defects along this mechanistic pathway may underlie HLH.

Role of adaptin protein complexes in intracellular trafficking and their impact on diseases

Adaptin proteins (APs) play a crucial role in intracellular cell trafficking. The 'classical' role of APs is carried out by AP1‒3, which bind to clathrin, cargo, and accessory proteins. Accordingly, AP1-3 are crucial for both vesicle formation and sorting. All APs consist of four subunits that are indispensable for their functions. In fact, based on studies using cells, model organism knockdown/knock-out, and human variants, each subunit plays crucial roles and contributes to the specificity of each AP. These studies also revealed that the sorting and intracellular trafficking function of AP can exert varying effects on pathology by controlling features such as cell development, signal transduction related to the apoptosis and proliferation pathways in cancer cells, organelle integrity, receptor presentation, and viral infection. Although the roles and functions of AP1‒3 are relatively well studied, the functions of the less abundant and more recently identified APs, AP4 and AP5, are still to be investigated. Further studies on these APs may enable a better understanding and targeting of specific diseases.APs known or suggested locations and functions.

Hemophagocytic Lymphohistiocytosis

CONTEXT.—

Hemophagocytic lymphohistiocytosis (HLH) is a rare, life-threatening disorder of immune regulation that can eventually result in end-organ damage and death. HLH is characterized by uncontrolled activation of cytotoxic T lymphocytes, natural killer cells, and macrophages that can lead to a cytokine storm. The diagnosis of HLH is often challenging due to the diverse clinical manifestations and the presence of several diagnostic mimics. The prognosis is generally poor, warranting rapid diagnosis and aggressive management.

OBJECTIVE.—

To provide a comprehensive review of the pathogenesis, clinical features, diagnosis, and management of HLH.

DATA SOURCES.—

Peer-reviewed literature.

CONCLUSIONS.—

HLH is a condition where a complete understanding of the pathogenesis, early diagnosis, and proper management has an important role in determining patient outcome. Genetic mutations causing impairment in the function of cytotoxic T lymphocytes and natural killer cells have been identified as the root cause of familial HLH; however, the specific pathogenesis of acquired HLH is unclear. The HLH-2004 protocol used in the diagnosis of HLH was originally developed for the pediatric population. The HLH-2004 protocol still forms the basis of the diagnosis of HLH in adults, although its use in adults has not been formally validated yet. Treatment of HLH is primarily based on the HLH-94 protocol, which involves suppressing the inflammatory response, but the treatment needs to be modified in adults depending on the underlying cause and comorbidities.

Spectrum mutations of PRF1, UNC13D, STX11, and STXBP2 genes in Vietnamese patients with hemophagocytic lymphohistiocytosis

INTRODUCTION

The prevalence of gene mutations in hemophagocytic lymphohistiocytosis (HLH) varied between studies. Thus far, data on the genetic background of HLH in Vietnamese patients are limited.

METHODS

We recruited 94 HLH patients and analyzed for the 4 genes using Sanger sequencing technology.

RESULTS

Pathogenic variants were observed in 36 (38.29%) patients, including 27 in UNC13D, 5 in STXBP2, 3 in PRF1, and 2 in STX11 (one patient with digenic variants in both UNC13D and STX11). Monoallelic variants accounted for 77.8% of all cases with mutation. A total of 23 different types of pathogenic variants were documented in the 4 genes tested, including 15 in UNC13D, 3 in PRF1, 3 in STXBP2, and 2 in STX11. Interestingly, the novel splicing variant c.3151G>A in UNC13D was recurrently identified in 8 unrelated patients.

CONCLUSION

Vietnamese patients with HLH showed a distinct genetic variant spectrum, in which UNC13D is the predominant genetic lesion associated with HLH.

Germline variants in UNC13D and AP3B1 are enriched in COVID-19 patients experiencing severe cytokine storms

Critically ill coronavirus disease 2019 (COVID-19) is characterized by severe cytokine storms, a hyperinflammatory condition intimately related to the development of fatal outcomes. Why some individuals seem particularly vulnerable to severe cytokine storms is still unknown. Primary immunodeficiency (PID)-related genes are inherited factors that dysregulate host inflammatory responses to infection, especially hemophagocytic lymphohistiocytosis (HLH)-related genes, established as contributors to the development of excessive cytokine storms. We analyzed the association between PID gene variants with severe cytokine storms in COVID-19. We conducted whole-exome sequencing in 233 hospitalized COVID-19 patients and identified four PID gene (UNC13D, AP3B1, RNF168, DHX58) variants were significantly enriched in COVID-19 patients experiencing severe cytokine storms. The total percentage of COVID-19 patients with variants in UNC13D or AP3B1, two typical HLH genes, was dramatically higher in high-level cytokine group than in low-level group (33.3 vs. 5.7%, P < 0.001). Germline variants in UNC13D and AP3B1 were associated with the development of severe cytokine storms, fatal outcomes in COVID-19. These findings advance the understanding of individual susceptibility to severe cytokine storms and help optimize the current management of COVID-19.

Inherited Genetic Susceptibility to Nonimmunosuppressed Epstein-Barr Virus-associated T/NK-cell Lymphoproliferative Diseases in Chinese Patients

Epstein-Barr virus (EBV) T/NK-cell lymphoproliferative diseases are characterized by clonal expansion of EBV-infected T or NK cells, including chronic active EBV infection of T/NK-cell type (CAEBV+T/NK), EBV-associated hemophagocytic lymphohistiocytosis (EBV+HLH), extranodal NK/T-cell lymphoma of nasal type (ENKTL), and aggressive NK-cell leukemia (ANKL). However, the role of inherited genetic variants to EBV+T/NK-LPDs susceptibility is still unknown. A total of 171 nonimmunosuppressed patients with EBV+T/NK-LPDs and 104 healthy donors were retrospectively collected and a targeted sequencing study covering 15 genes associated with lymphocyte cytotoxicity was performed. The 94 gene variants, mostly located in UNC13D, LYST, ITK, and PRF1 genes were detected, and mutations covered 28/50 (56.00%) of CAEBV-T/NK, 31/51 (60.78%) of EBV+HLH, 13/28 (46.42%) of ENKTL, and 13/48 (27.09%) of ANKL. Most mutations represented monoallelic and missense. Three-year overall survival rate of patients with CAEBV-T/NK and EBV+HLH was significantly lower in patients with germline mutations than in those without germline mutations (P=0.0284, P=0.0137). Our study provided novel insights into understanding a spectrum of nonimmunosuppressed EBV+T/NK-LPDs with respect to genetic defects associated with lymphocyte cytotoxicity and reminded us that the gene sequencing may be an auxiliary test for diagnosis and risk stratification of EBV+T/NK-LPDs.

Identification of germline variants in adults with hemophagocytic lymphohistiocytosis

Some germline variants are predicted to disrupt protein function in HLH-associated genes. Such variants are neither enriched in adult-onset HLH nor associated with specific clinical or laboratory features of HLH.

The Novel Regulatory Role of lncRNA-miRNA-mRNA Axis in Amyotrophic Lateral Sclerosis: An Integrated Bioinformatics Analysis

Amyotrophic lateral sclerosis (ALS) is an incurable neurodegenerative disease that primarily affects motor neurons, causing muscle atrophy, bulbar palsy, and pyramidal tract signs. However, the aetiology and pathogenesis of ALS have not been elucidated to date. In this study, a competitive endogenous RNA (ceRNA) network was constructed by analyzing the expression profiles of messenger RNAs (mRNAs) and long noncoding RNAs (lncRNAs) that were matched by 7 ALS samples and 4 control samples, and then a protein-protein interaction (PPI) network was constructed to identify the genes related to ALS. Gene Ontology (GO) was used to study the potential functions of differentially expressed mRNAs (DEmRNAs) in the ceRNA network. For the ALS and control groups, 247177 potential lncRNA-mRNA ceRNA relationship pairs were screened. Analysis of significant relationship pairs demonstrated that the PPI modules formed by the MALAT1-regulated SYNRG, ITSN2, PICALM, AP3B1, and AAK1 genes may play important roles in the pathogenesis of ALS, and these results may help to characterize the pathogenesis of ALS.

Clinical Management of Relapsed/Refractory Hemophagocytic Lymphohistiocytosis in Adult Patients: A Review of Current Strategies and Emerging Therapies

Introduction

Haemophagocytic lymphohistiocytosis (HLH) is a severe disorder with high mortality. The aim of this review is to update clinical management of relapsed/refractory HLH in adults, with a focus on current and new therapies.

Methods

We searched relevant articles in Embase and PUBMED with the MESH term “hemophagocytic lymphohistiocytosis; refractory; relapsing; adult.”

Results

One hundred eight papers were found; of these, 22 were retained for this review. The treatment of HLH in adult is based on the HLH-94 regimen. The response rate is lower than in pediatric patients, and 20–30% are refractory to this therapy. DEP regimen and allogenic hematopoietic stem cell transplantation (HSCT) are associated with complete response and partial response in 27% and 49.2%, respectively. However, many patients fail to achieve a stable condition before HSCT, and mortality is higher in them. New drugs have been developed, such as emapalumab, ruxolitinib, and alemtuzumab, and they may be used as bridges to the curative HSCT. They are relatively well tolerated and have few or mild side effects. With these agents, the rate of partial response ranges from 14.2% to 100%, while the rate of complete response is highly variable according to study and medication used. The number of patients who achieved HSCT ranged from 44.8% to 77%, with a survival rate of 55.9% to 100%. However, the populations in these studies are mainly composed of mixed-age patients (pediatric and adult patients), and studies including only adult patients are scarce.

Conclusion

Relapsed or refractory HLH in adult patients is associated with poor outcome, and consolidation with HSCT may be required in some cases. Mortality related to HSCT is mainly due to active HLH disease before HSCT and post HSCT complications. New drugs, such as empalumab, ruxolitinib, and alemtuzumab are interesting since these agents may be used as bridges to HSCT with increases in the numbers of patients proceeding to HSCT and survival rate.

Adult onset type 2 familial hemophagocytic lymphohistiocytosis with PRF1 c.65delC/c.163C>T compound heterozygous mutations: A case report

BACKGROUND

Familial hemophagocytic lymphohistiocytosis (FHL) is a primary immunodefici-ency disease caused by gene defects. The onset of FHL in adolescents and adults may lead clinicians to ignore or even misdiagnose the disease. To the best of our knowledge, this is the first report to detail the clinical features of type 2 FHL (FHL2) with compound heterozygous perforin (PRF1) defects involving the c.163C>T mutation, in addition to correlation analysis and a literature review.

CASE SUMMARY

We report a case of a 27-year-old male patient with FHL2, who was admitted with a persistent fever and pancytopenia. Through next-generation sequencing technology of hemophagocytic lymphohistiocytosis (HLH)-related genes, we found compound heterozygous mutations of PRF1: c.65delC (p.Pro22Argfs*29) (frameshift mutation, paternal) and c.163C>T (p.Arg55Cys) (missense mutation, maternal). Although he did not receive hematopoietic stem cell transplantation, the patient achieved complete remission after receiving HLH-2004 treatment protocol. To date, the patient has stopped taking drugs for 15 mo, is in a stable condition, and is under follow-up observation.

CONCLUSION

The delayed onset of FHL2 may be related to the PRF1 mutation type, pathogenic variation pattern, triggering factors, and the temperature sensitivity of some PRF1 mutations. For individual, the detailed reason for the delay in the onset of FHL warrants further investigation.

Emapalumab for adult and pediatric patients with hemophagocytic lymphohistiocytosis

INTRODUCTION

Hemophagocytic lymphohistiocytosis (HLH) is a rare life-threatening hyperinflammatory syndrome. Standard treatment is based on immunosuppressive, cytotoxic drugs and hematopoietic stem cell transplantation (HSCT) in primary HLH. Interferon-gamma (IFN-γ) plays a key pathogenic role. Emapalumab, a monoclonal antibody directed against IFN-γ, is the first target therapy approved for primary HLH with refractory, recurrent or progressive disease or intolerance to conventional therapy.

AREAS COVERED

We reviewed the pharmacological characteristics, safety, efficacy and clinical uses of emapalumab. We summarized the results of current standard treatment based on chemo-immunosuppressive protocols and outlined the alternative options available.

EXPERT OPINION

Emapalumab is an effective treatment for HLH with a good safety profile. Its efficacy was demonstrated in a phase II/III study on primary HLH pediatric patients with refractory, relapsing HLH or intolerance to first-line treatment. The use of emapalumab allowed most patients to proceed to HSCT, with a high estimated probability of survival 12 months after transplantation. The outcomes in patients who underwent transplantation compare favorably with those reported previously with either myeloablative or reduced-intensity conditioning regimens. The potential role of emapalumab in the treatment of secondary HLH and as a prevention of graft failure after HSCT deserves to be further assessed.

Outcomes and prognostic factors associated with 180-day mortality in Taiwanese pediatric patients with Hemophagocytic Lymphohistiocytosis

BACKGROUND/PURPOSE

Hemophagocytic lymphohistiocytosis (HLH), a rarely occurring syndrome with various triggers, is associated with early mortality. Owing to a lack of sufficient corresponding data in Taiwan, this study aimed to identify the outcome and potential factors associated with 180-day mortality in pediatric HLH.

METHODS

This retrospective study analyzed clinical and laboratory data on pediatric patients diagnosed with HLH at our institute (1995-2019). Logistic regression analysis was conducted to determine the associations between various factors and 180-day mortality.

RESULTS

Overall, 48 patients had HLH; their median age at diagnosis was 5 years (interquartile range: 2-11 years). Clinical presentations and laboratory parameters required for diagnosis included fever (98%), splenomegaly (79%), hyperferritinemia (98%), hemophagocytosis (94%), thrombocytopenia (90%), anemia (63%), hypertriglyceridemia (68%), and neutropenia (57%). The 5-year overall survival (OS) rate was 49%. Of 22 patients who had died at the last follow-up, 15 (68%) died within 180 days after diagnosis. In the multivariate analysis, hemoglobin (odds ratio [OR]: 0.564, p = 0.024) and triglyceride (OR: 1.004, p = 0.049) were significantly associated with 180-day mortality. Higher triglyceride levels at diagnosis were related to significantly lower 180-day OS rates (52.9% vs. 86.1%, p = 0.018).

CONCLUSION

The overall outcome in our cohort was similar to that reported in some of the largest international cohorts. Hypertriglyceridemia and anemia may be indicative of poor prognoses in pediatric HLH patients independently and may be used to guide treatment strategy formulations for better outcomes.

Hämophagozytische Syndrome beim Erwachsenen

Die Hämophagozytische Lymphohistiozytose (HLH) ist ein Zytokinsturm-Syndrom, das bei Erwachsenen in der Regel durch Malignome, Infektionen oder autoinflammatorische/autoimmunologische Erkrankungen ausgelöst wird. In der Rheumatologie ist das Erkrankungsbild besser als Makrophagenaktivierungs-Syndrom bekannt (MAS-HLH). Die HLH entsteht auf dem Boden eines genetisch bedingten und/oder erworbenen dysfunktionalen Immunsystems. Im Unterschied zur hereditären primären HLH (pHLH) bei Kindern findet sich bei der adulten, zumeist sekundären HLH (sHLH) nur sehr selten eine monogenetische Ursache. In Einzelfällen kann sich aber eine „late onset“-genetische HLH auch erst im Erwachsenenalter manifestieren. Die Diagnose von HLH und MAS wird verzögert durch die unspezifische Symptomatik (Fieber, Zytopenie, Ferritinanstieg, Splenomegalie, Multiorganversagen), die sich mit der Grunderkrankung oder einem SIRS überlagern kann. Die namengebende Hämophagozytose lässt sich nur bei einem Teil der Patienten nachweisen. sHLH und MAS-HLH weisen unbehandelt eine hohe Mortalität auf. Diagnosekriterien für pHLH und MAS sowie das standardisierte HLH-2004-Therapieprotokoll wurden in der Pädiatrie kontinuierlich in klinischen Studien entwickelt. In angepasster Form werden Kriterien und Substanzen des pädiatrischen HLH-Protokolls auch bei Erwachsenen angewendet. Zunehmend kommen neue Therapien zum Einsatz, welche die Hyperzytokinämie und deren Auswirkungen bei HLH und MAS bremsen (z. B. Ruxolitinib oder Anakinra). Der folgende Artikel soll eine Übersicht zu Epidemiologie, Diagnostik und Therapie von HLH und MAS bei Erwachsenen geben.

The use of anakinra in the treatment of secondary hemophagocytic lymphohistiocytosis

BACKGROUND

Hemophagocytic lymphohistiocytosis (HLH) can be familial or secondary, which is often triggered by infection or malignancy. HLH therapy includes dexamethasone and etoposide. However, therapy is associated with significant morbidity and mortality. Anakinra, a recombinant interleukin-1 receptor antagonist, has been reported to treat macrophage activation syndrome (MAS), rheumatic sHLH. We report our experience with anakinra to treat patients with nonrheumatic secondary HLH (sHLH).

PROCEDURE

Six children were diagnosed with HLH from December 2014 to August 2016 and were treated with subcutaneous anakinra (6-10 mg/kg/day divided over four doses) with or without dexamethasone (10 mg/m² /day). Therapy was either escalated or weaned based on clinical and laboratory response.

RESULTS

Five of six patients were treated with anakinra and dexamethasone, and one with anakinra alone due to active cytomegalovirus (CMV) pneumonitis. The median age of diagnosis was 1.8 years (range 0.8-14.9 years). No pathogenic mutations associated with HLH were identified, but three of six possessed genetic variants of unknown significance. Infectious triggers were identified for four patients and two patients had malignancies. The average treatment duration was 8 weeks with 3.5-5.5 years of follow up. No patient needed escalation of therapy to include etoposide. All patients achieved remission. Anakinra was well tolerated without significant adverse effects.

CONCLUSION

Initial treatment with anakinra (with or without dexamethasone) is a feasible treatment alternative for patients with secondary HLH and may allow for avoidance of etoposide. We recommend early initiation of anakinra when HLH is suspected. A broader investigation of the use of anakinra as a first-line agent for HLH is ongoing.

When Actin is Not Actin' Like It Should: A New Category of Distinct Primary Immunodeficiency Disorders

An increasing number of primary immunodeficiencies (PIDs) have been identified over the last decade, which are caused by deleterious mutations in genes encoding for proteins involved in actin cytoskeleton regulation. These mutations primarily affect hematopoietic cells and lead to defective function of immune cells, such as impaired motility, signaling, proliferative capacity, and defective antimicrobial host defense. Here, we review several of these immunological "actinopathies" and cover both clinical aspects, as well as cellular mechanisms of these PIDs. We focus in particular on the effect of these mutations on human neutrophil function.

A novel prognostic model for adult patients with Hemophagocytic Lymphohistiocytosis

BACKGROUND

Hemophagocytic Lymphohistiocytosis (HLH) is a type of rare disease with low survival rate. We aimed to develop a model to evaluate the six-month prognosis in adult HLH patients. The data at discharge (will be called as post-treatment) for newly diagnosed adult HLH patients was collected and independent prognostic variables were selected for inclusion in the model.

RESULTS

Three laboratory markers were confirmed to be the independent risk factors (ferritin: hazard ratio (HR) 0.101, 95% confidence interval (CI) 0.036-0.282, P<0.001; platelets: HR 4.799, 95% CI 1.884-12.223, P = 0.001; alanine aminotransferase (ALT): HR 0.423, 95% CI 0.180-0.997, P = 0.049). These were included in the final clinical prediction model. Receiver operating characteristic (ROC) curves disclosed that this model had a better discrimination (area under the curve (AUC) = 0.842, 95% CI 0.773-0.910, P < 0.001) than each of them alone and the calibration curves aligned completely with the model predictions and actual observations. Kaplan-Meier curves revealed a significant difference in the overall survival (OS) in patients stratified by the model with higher values associated with a better OS.

CONCLUSION

These results point out that serum ferritin, platelets and ALT levels are independent elements of OS in adult patients with HLH, and that the proposed model have a better prognostic value than any of these markers alone.

The genetics of macrophage activation syndrome

Macrophage activation syndrome (MAS), or secondary hemophagocytic lymphohistiocytosis (HLH), is a cytokine storm syndrome associated with multi-organ system dysfunction and high mortality rates. Laboratory and clinical features resemble primary HLH, which arises in infancy (1 in 50,000 live births) from homozygous mutations in various genes critical to the perforin-mediated cytolytic pathway employed by NK cells and cytotoxic CD8 T lymphocytes. MAS/secondary HLH is about ten times more common and typically presents beyond infancy extending into adulthood. The genetics of MAS are far less defined than for familial HLH. However, the distinction between familial HLH and MAS/secondary HLH is blurred by the finding of heterozygous perforin-pathway mutations in MAS patients, which may function as hypomorphic or partial dominant-negative alleles and contribute to disease pathogenesis. In addition, mutations in a variety of other pathogenic pathways have been noted in patients with MAS/secondary HLH. Many of these genetically disrupted pathways result in a similar cytokine storm syndrome, and can be broadly categorized as impaired viral control (e.g., SH2P1A), dysregulated inflammasome activity (e.g., NLRC4), other immune defects (e.g., IKBKG), and dysregulated metabolism (e.g., LIPA). Collectively these genetic lesions likely combine with states of chronic inflammation, as seen in various rheumatic diseases (e.g., still disease), with or without identified infections, to result in MAS pathology as explained by the threshold model of disease. This emerging paradigm may ultimately support genetic risk stratification for high-risk chronic and even acute inflammatory disorders. Moving forward, continued whole-exome and -genome sequencing will likely identify novel MAS gene associations, as well as noncoding mutations altering levels of gene expression.

Decitabine in combination with low-dose cytarabine, aclarubicin and G-CSF tends to improve prognosis in elderly patients with high-risk AML

We evaluated the risk status and survival outcomes of 125 elderly acute myeloid leukemia (AML) patients treated with decitabine in combination with low-dose cytarabine, aclarubicin, and G-CSF (D-CAG). The risk status was evaluated by determining the frequency of recurring gene mutations using next-generation sequencing (NGS) analysis of 23 selected genes and cytogenetic profiling of bone marrow samples at diagnosis. After a median follow-up of 12 months (range: 2-82 months), 86 patients (68.8%) had achieved complete remission after one cycle of induction, and 94 patients (75.2%) had achieved it after two cycles. The median overall survival (OS) and disease-free survival (DFS) were 16 and 12 months, respectively. In 21 AML patients aged above 75 years, the median OS and DFS were longer in the low- and intermediate-risk group than the high-risk group, but the differences were not statistically significant. The median OS and DFS were similar in patients with or without TET2, DNMT3A, IDH2, TP53 and FLT3 mutations. Multivariate analysis showed that patient age above 75 years, high-risk status, and genetic anomalies, like deletions in chromosomes 5 and/or 7, were significant variables in predicting OS. D-CAG regimen tends to improve the prognosis of a subgroup of elderly patients with high-risk AML.

Hermansky-Pudlak syndrome: Mutation update

Hermansky-Pudlak syndrome (HPS) is a group of 10 autosomal recessive multisystem disorders, each defined by the deficiency of a specific gene. HPS-associated genes encode components of four ubiquitously expressed protein complexes: Adaptor protein-3 (AP-3) and biogenesis of lysosome-related organelles complex-1 (BLOC-1) through -3. All individuals with HPS exhibit albinism and a bleeding diathesis; additional features occur depending on the defective protein complex. Pulmonary fibrosis is associated with AP-3 and BLOC-3 deficiency, immunodeficiency with AP-3 defects, and gastrointestinal symptoms are more prevalent and severe in BLOC-3 deficiency. Therefore, identification of the HPS subtype is valuable for prognosis, clinical management, and treatment options. The prevalence of HPS is estimated at 1-9 per 1,000,000. Here we summarize 264 reported and novel variants in 10 HPS genes and estimate that ~333 Puerto Rican HPS subjects and ~385 with other ethnicities are reported to date. We provide pathogenicity predictions for missense and splice site variants and list variants with high minor allele frequencies. Current cellular and clinical aspects of HPS are also summarized. This review can serve as a manifest for molecular diagnostics and genetic counseling aspects of HPS.

Adult haemophagocytic lymphohistiocytosis: a Review

BACKGROUND

Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening disorder characterized by hyperimmune response. The mortality is high despite progress being made in the diagnosis and treatment of the disease.

AIM

This review aimed to update knowledge on adult HLH pathophysiology, identifiy the numerous causes, and help clinicians make early diagnosis and initiate treatment.

DESIGN AND METHODS

Using Embase, we searched relevant articles published from January 1, 2010 to October 31, 2019, with the MESH term « hemophagocytic lymphohistiocytosis; macrophagic activation syndrome, adult ».

RESULTS

The mean age at presentation is about 50 years, with a male predominance. The most frequent disease associations are haematological diseases, viral or bacterial infections, and autoimmune diseases. The pathophysiologic mechanism is probably the combination of inherited genetic mutations and extrinsic triggers. The mortality rate is 26.5% to 74.8%. H-score is more efficient than HLH-2004 criteria to identify HLH, with diagnostic sensitivity and specificity 90% and 79%, respectively.18F-FDG PET/CT is potentially useful for detecting underlying disease and the extent of secondary HLH. Disease-specific treatment should be given as soon as possible. Treatment with corticosteroids combined or not with etoposide is the mainstay of treatment. Monoclonal antibodies and JAK pathway inhibitors show promise of being effective.

CONCLUSION

In adult HLH, infectious diseases, autoimmune disease and malignancy should be suspected so that disease-specific treatment can be given promptly. Treatment with corticosteroids combined or not with etoposide is the mainstay of treatment, but new therapies show promise of being effective.

Application of blood and immunodeficiency gene detection in the diagnosis of hemophagocytic lymphohistiocytosis patients

To investigate the value of genetic mutations in the pathogenesis and differential diagnosis of hemophagocytic lymphohistiocytosis (HLH), mutations related to blood and immune deficiency genes were analyzed in patients with HLH. Peripheral blood samples from 33 children diagnosed with HLH on the basis of the 2004 diagnostic criteria were collected, and 317 genes related to blood system diseases and 562 genes related to immunodeficiency were detected by second-generation targeted sequencing technology, bioinformatic analysis, and parental verification analysis. A total of 159 mutations related to blood system diseases and immunodeficiency were found in 33 patients, including 7 HLH-related gene mutations (UNC13D, XIAP, LYST, STX11, ITK, PRF1, and SRGN) in 12 patients. UNC13D was found in 6 patients, with the highest frequency. Two cases (6.1%, 2/33) were diagnosed as primary hemophagocytic lymphohistiocytosis (pHLH), and 6 cases (18.2%, 6/33) were diagnosed as primary immunodeficiency disease (PID) or hereditary hematopathy; the remainder were diagnosed as secondary hemophagocytic lymphohistiocytosis (sHLH). It is necessary to detect blood and immunodeficiency genes to exclude the possibility of pHLH, PID, or hereditary hematopathy associated with HLH for children.