MHC class II deficiency: Clinical, immunological, and genetic insights in a large multicenter cohort.

BACKGROUND: Major Histocompatibility Complex Class II (MHC-II) deficiency, a combined immunodeficiency, results from loss of Human Leukocyte Antigen class II expression on antigen-presenting cells. Currently, hematopoietic stem cell transplantation (HSCT) stands as the sole curative approach, though factors influencing patient outcomes remain insufficiently explored. OBJECTIVE: Our aim was to elucidate the clinical, immunological, and genetic profiles associated with MHC-II deficiency and identify prognostic indicators that affect survival rates. METHODS: In this multicenter retrospective analysis, we gathered data from 35 patients diagnosed with MHC-II deficiency across 12 centers in Turkey. We recorded infection histories, gene mutations, immune cell subsets, and surface MHC-II expression on blood cells. We conducted survival analyses to evaluate the impact of various factors on patient outcomes. RESULTS: Predominant symptoms observed were pneumonia (n=29, 82.9%), persistent diarrhea (n=26, 74.3%), and severe infections (n=26, 74.3%). The RFXANK gene mutation (n=9) was the most frequent, followed by mutations in RFX5 (n=8), CIITA (n=4), and RFXAP (n=2) genes. Patients with RFXANK mutations presented with later onset and diagnosis compared to those with RFX5 mutations (p=0.0008 and p=0.0006, respectively), alongside a more significant diagnostic delay (p=0.020). A notable founder effect was observed in 5 patients with a specific RFX5 mutation (c.616G>C). The overall survival rate for patients was 28.6% (n=10), showing a significantly higher proportion in individuals with HSCT (n=8, 80%). Early demise (p=0.006) and higher CD8+ T-cell counts were observed in patients with the RFX5 mutations compared to RFXANK-mutant patients (p=0.006 and p=0.009, respectively). CONCLUSION: The study delineates the genetic and clinical panorama of MHC-II deficiency, emphasizing the prevalence of specific gene mutations such as RFXANK and RFX5. These insights facilitate early diagnosis and prognosis refinement, significantly contributing to the management of MHC-II deficiency.

Toxic Skin Reactions Should Be Differentiated from Allergic Reactions to Chemotherapeutic Drugs in Children: A Case Series and Review of the Literature.

Background: Chemotherapeutic drugs can lead to a wide spectrum of cutaneous findings, ranging from nonimmune toxic reactions to severe immune-mediated hypersensitivity reactions. The aim of this study was to evaluate the clinical, histopathological features, and prognosis of toxic skin reactions to chemotherapeutic drugs and to compare them with characteristics of immune-mediated reactions in children with malignancies. Methods: The medical records of all children with cancer who experienced skin reactions after chemotherapy administration and diagnosed as a toxic skin reaction between 2010 and 2022 were retrospectively analyzed. The diagnosis was re-evaluated and differentiated from other similar disorders by using clinical manifestations, photodocumentation, and histopathological findings. Results: A total of 17 children aged 2-17 years were involved: toxic erythema of chemotherapy (TEC) in 14 children, methotrexate-induced epidermal necrosis in 2 children, and toxic epidermal necrolysis (TEN)-like TEC in 1 child. The most commonly implicated drug was methotrexate. Most patients recovered rapidly after drug cessation and supportive measures. In 10 of the 17 patients, reintroduction of the culprit chemotherapeutic drug at reduced doses or increased dosage intervals was possible without any recurrence. Six patients could not receive further doses since they deceased due to sepsis and other complications. Conclusions: Cutaneous toxic eruptions to chemotherapeutic drugs may present with a severe phenotype resembling Stevens-Johnson syndrome/TEN. An accurate diagnosis prevents potentially harmful therapeutic interventions, withholding of chemotherapy, and erroneous assignment of drug allergies.

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

BACKGROUND: 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. OBJECTIVE: 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. METHODS: 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. RESULTS: 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. CONCLUSIONS: 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 novel G6PC3 gene mutation in severe congenital neutropenia: pancytopenia and variable bone marrow phenotype can also be part of this syndrome.

Glucose-6-phosphatase catalytic subunit 3 (G6PC3) deficiency is a newly described syndrome characterized by severe congenital neutropenia associated with multiple organ abnormalities including cardiac and urogenital malformations. The underlying pathophysiology of increased apoptosis of myeloid cells and of neutrophil dysfunction in G6PC3 deficiency involves disturbed glucose metabolism, increased endoplasmic reticulum stress and deficient protein folding. Here, we report a new case of G6PC3 deficiency caused by a novel homozygous G6PC3 gene mutation p.Trp59Arg. The patient showed pancytopenia and a variable bone marrow phenotype with maturation arrest and vacuolization in myeloid lineage cells and a normocellular marrow, respectively. She also showed persistent lymphopenia with low CD4 T- and CD19 B-cell counts. Lymphopenia and even pancytopenia as well as a variable bone marrow phenotype can be part of this syndrome. These clinical findings in a patient with chronic neutropenia should alert the clinician to consider a diagnosis of G6PC3 deficiency.

A new hemostatic agent--Ankaferd blood stopper: management of gastrointestinal bleeding in an infant and other experiences in children.

Ankaferd blood stopper (ABS) is a standardized medicinal plant extract that stimulates the formation of an encapsulated protein network that provides focal points for erythrocyte aggregation. It has a therapeutic potential to be used for the management of external hemorrhage. Here, the authors report an infant bleeding from peptic ulcer was stopped successfully by gastroscopic application of ABS and other cases that used topical ABS for mucosal bleedings are also presented.

A novel L218P mutation in NADH-cytochrome b5 reductase associated with type I recessive congenital methemoglobinemia.

The presence of central cyanosis that is unrelated to cardiopulmonary causes alerts clinicians to a possible diagnosis of methemoglobinemia. Congenital methemoglobinemia due to deficiency of nicotinamide-adenine dinucleotide (NADH)-cytochrome b5 reductase (cb(5)r) is an autosomal recessive disorder characterized by life long cyanosis. Here we report a six-year old boy who presented with central cyanosis and upon examination revealed a methemoglobin level of 19.0%. Sequencing the CYB5R3 gene identified a homozygous T-->C transition at base c.653, which changed codon 218 from leucine to proline (L218P) in cb(5)r protein. Treatment with ascorbic acid relieved the cyanosis and returned methemoglobin levels to normal.