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.

Genetic Evaluation of the Patients with Clinically Diagnosed Inborn Errors of Immunity by Whole Exome Sequencing: Results from a Specialized Research Center for Immunodeficiency in Türkiye.

Molecular diagnosis of inborn errors of immunity (IEI) plays a critical role in determining patients' long-term prognosis, treatment options, and genetic counseling. Over the past decade, the broader utilization of next-generation sequencing (NGS) techniques in both research and clinical settings has facilitated the evaluation of a significant proportion of patients for gene variants associated with IEI. In addition to its role in diagnosing known gene defects, the application of high-throughput techniques such as targeted, exome, and genome sequencing has led to the identification of novel disease-causing genes. However, the results obtained from these different methods can vary depending on disease phenotypes or patient characteristics. In this study, we conducted whole-exome sequencing (WES) in a sizable cohort of IEI patients, consisting of 303 individuals from 21 different clinical immunology centers in Türkiye. Our analysis resulted in likely genetic diagnoses for 41.1% of the patients (122 out of 297), revealing 52 novel variants and uncovering potential new IEI genes in six patients. The significance of understanding outcomes across various IEI cohorts cannot be overstated, and we believe that our findings will make a valuable contribution to the existing literature and foster collaborative research between clinicians and basic science researchers.

Comparison of clinical features of cystic fibrosis patients eligible but not on CFTR modulators to ineligible for CFTR modulators.

INTRODUCTION: Cystic fibrosis transmembrane conductance regulator (CFTR) modulator drugs target the underlying defect and improve CFTR function. They are a part of standard care in many countries, but not all patients are eligible for these drugs due to age and genotype. Here, we aimed to determine the characteristics of non-eligible patients for CFTR modulators in the CF registry of Turkey (CFRT) to highlight their clinical needs. METHODS: This retrospective cohort study included CF patient data from the CFRT in 2021. The decision of eligibility for the CFTR modulator was determined according to the 'Vertex treatment-Finder' on the Vertex® website. Demographic and clinical characteristics of patients were compared between eligible (group 1) and ineligible (group 2) groups for CFTR modulators. RESULTS: Among the study population (N = 1527), 873 (57.2%) were in group 1 and 654 (42.8%) were in group 2. There was no statistical difference between groups regarding sex, meconium ileus history, diagnoses via newborn screening, FEV1 z-score, CF-associated complications, organ transplant history, and death. Patients in group 2 had a higher incidence of pancreatic insufficiency (87.7% vs. 83.2%, p = .010), lower median height z-scores (-0.87 vs. -0.55, p < .001), lower median body mass index z-scores (-0.65 vs. -0.50, p < .001), longer days receiving antibiotics due to pulmonary exacerbation (0 [interquartile range, IQR: 0-2] vs. 0 [IQR: 0-7], p = 0.001), and more non-invasive ventilation support (2.6% vs. 0.9%, p = 0.008) than patients in group 1. CONCLUSION: The ineligible group had worse clinical outcomes than the eligible group. This highlights their need for life-changing drugs to improve clinical outcomes.

Comparison of refugee patients with cystic fibrosis and their counterpart children from Turkey during the war.

Since the outbreak of the Syrian civil war in 2011, the population of Arab refugees in Turkey has rapidly increased. While cystic fibrosis (CF) is believed to be rare among Arabs, recent studies suggest it is underdiagnosed. This study aims to present the demographic, clinical, and genetic characteristics of CF patients among Arab refugees in Turkey. Additionally, a comparison is made between the findings in the National CF Registry 2021 in Turkey (NCFRT) and the refugee CF patient group. The study included refugee patients between the ages of 0 and 18 years who were diagnosed with CF and received ongoing care at pediatric pulmonology centers from March 2011 to March 2021. The study examined demographic information, age at diagnosis, age of diagnosis of patients through CF newborn screening (NBS), presenting symptoms, CF transmembrane conductance regulator (CFTR) mutation test results, sputum culture results, weight, height, and body mass index (BMI) z score. Their results were compared with the NCFRT results. The study included 14 pediatric pulmonology centers and 87 patients, consisting of 46 (52.9%) boys and 41 (47.1%) girls. All of the patients were Arab refugees, with 80 (92%) being Syrian. All the patients were diagnosed in Turkey. The median age at diagnosis of patients was 22.33 (interquartile range, 1-258) months. The median age of diagnosis of patients through NBS was 4.2 (interquartile range, 1-12) months. The median age of older patients, who were unable to be included in the NBS program, was 32.3 (interquartile range, 3-258) months. Parental consanguinity was observed in 52 (59.7%) patients. The mutation that was most frequently found was F508del, which accounted for 22.2% of the cases. It was present in 20 patients, constituting 32 out of the total 144 alleles. There was a large number of genetic variations. CFTR genotyping could not be conducted for 12 patients. These patients had high sweat tests, and their genetic mutations could not be determined due to a lack of data. Compared to NCFRT, refugee patients were diagnosed later, and long-term follow-up of refugee CF patients had significantly worse nutritional status and pseudomonas colonization.  Conclusion: Although refugee CF patients have equal access to NBS programs and CF medications as well as Turkish patients, the median age at diagnosis of patients, the median age of diagnosis of patients through NBS, their nutritional status, and Pseudomonas colonization were significantly worse than Turkish patients, which may be related to the difficulties of living in another country and poor living conditions. The high genetic heterogeneity and rare mutations detected in the refugee patient group compared to Turkish patients. Well-programmed NBS programs, thorough genetic studies, and the enhancement of living conditions for refugee patients in the countries they relocate to can have several advantages such as early detection and improved prognosis. What is Known: • Children who have chronic diseases are the group that is most affected by wars. • The outcome gets better with early diagnosis and treatment in patients with Cystic Fibrosis (CF). What is New: • Through the implementation of a newborn screening program, which has never been done in Syria previously, refugee patients, the majority of whom are Syrians were diagnosed with cystic fibrosis within a duration of 4 months. • Despite equal access to the newborn screening program and CF medications for both Turkish patients and refugee patients, the challenges of living in a foreign country have an impact on refugees.