Primary immune regulatory disorders (PIRD): expanding the mutation spectrum in Turkey and identification of sixteen novel variants.

Human Inborn Errors of Immunity (IEIs) encompass a clinically and genetically heterogeneous group of disorders, ranging from mild cases to severe, life-threatening types. Among these, Primary Immune Regulatory Disorders (PIRDs) constitute a subset of IEIs characterized by diverse clinical phenotypes, prominently featuring severe atopy, autoimmunity, lymphoproliferation, hyperinflammation, autoinflammation, and susceptibility to malignancies. According to the latest report from the International Union of Immunological Societies (IUIS), PIRDs arise from mutations in various genes including LYST, RAB27A, AP3B1, AP3D1, PRF1, UNC13D, STX11, STXBP2, FAAP24, SLC7A7, RASGRP1, CD70, CTPS1, RLTPR, ITK, MAGT1, PRKCD, TNFRSF9, SH2DIA, XIAP, CD27 (TNFRSF7), FAS (TNFRSF6), FASLG (TNFSF6), CASP10, CASP8, FADD, LRBA, STAT3, AIRE, ITCH, ZAP70, TPP2, JAK1, PEPD, FOXP3, IL2RA, CTLA4, BACH2, IL2RB, DEF6, FERMT1, IL10, IL10RA, IL10RB, NFAT5, TGFB1, and RIPK1 genes. We designed a targeted next-generation sequencing (TNGS) workflow using the Ion AmpliSeq™ Primary Immune Deficiency Research Panel to sequence 264 genes associated with IEIs on the Ion S5™ Sequencer. In this study, we report the identification of 38 disease-causing variants, including 16 novel ones, detected in 40 patients across 15 distinct PIRD genes. The application of next-generation sequencing enabled rapid and precise diagnosis of patients with PIRDs.

An investigation of the etiology and follow-up findings in 35 children with overgrowth syndromes, including biallelic SUZ12 variant.

Overgrowth-intellectual disability (OGID) syndromes are clinically and genetically heterogeneous group of disorders. The aim of this study was to examine the molecular etiology and long-term follow-up findings of Turkish OGID cohort. Thirty-five children with OGID were included in the study. Single gene sequencing, clinical exome analysis, chromosomal microarray analysis and whole exome sequencing were performed. Five pathogenic copy number variants were detected in the patients; three of them located on chromosome 5q35.2 (encompassing NSD1), others on 9q22.3 and 22q13.31. In 19 of 35 patients; we identified pathogenic variants in OGID genes associated with epigenetic regulation, NSD1 (n = 15), HIST1H1E (n = 1), SETD1B (n = 1), and SUZ12 (n = 2). The pathogenic variants in PIK3CA (n = 2), ABCC9 (n = 1), GPC4 (n = 2), FIBP (n = 1), and TMEM94 (n = 1) which had a role in other growth pathways were detected in seven patients. The diagnostic yield was 31/35(88%). Twelve pathogenic variants were novel. The common facial feature of the patients was prominent forehead. The patients with Sotos syndrome were observed to have milder intellectual disability than patients with other OGID syndromes. In conclusion, this study showed, for the first time, that biallelic variants of SUZ12 caused Imagawa-Matsumoto syndrome, monoallelic variants in SETDIB resulted in OGID. Besides expanded the phenotypes of very rare OGID syndromes caused by FIBP and TMEM94.

A novel Mecom gene mutation associated with amegakaryocytic thrombocytopenia in a premature infant.

BACKGROUND: Hereditary bone marrow failure syndromes are a category of biologically different syndromes that can cause cytopenia in at least one hematopoietic cell lineage. CASE: We present a 29-week-old male infant who had a low Apgar Score, advanced delivery room resuscitation, widespread petechial rash, and ecchymoses at birth, without any dysmorphic features. Initial laboratory tests revealed bicytopenia (platelet count 7x10 3 /uL, hemoglobin of 3.9 g/dL, neutrophil 2.0x103 /uL) with findings of disseminated intravasculer coagulation (DIC). Imaging studies demonstrated accompanying left-sided congenital pulmonary airway malformation. On the second postnatal week pancytopenia occurred and the bone marrow findings were consistent with congenital amegakaryocytic thrombocytopenia. Further evaluations for differential diagnosis of pancitopenia were performed and the results of congenital viral infections, metabolic and immunologic tests were negative. While supportive treatments were in progress, haploidentical bone marrow transplantation (BMT) was performed from the father at 84th day due to unavailability of HLA-matched relative or nonrelative donor. Whole exome sequencing revealed a novel heterozygous frameshift variation (c.1242dupT [p. Thr538fs]) in exon 8 of the MECOM gene and validated by Sanger sequencing. No variation was detected in the parents genetic analysis. CONCLUSIONS: In this report, we present a patient with congenital bone marrow failure successfully treated with haploidentic BMT and describe a novel, de novo pathogenic variant in MECOM gene.

LSM1 is the new candidate gene for neurodevelopmental disorder.

Neurodevelopmental disorders are a heterogeneous group of diseases. Clinical presentation often overlaps with neurodevelopmental disorders, and explaining the molecular origin often requires reverse phenotyping. Next-Generation Sequencing (NGS) allows fast and cost-effective high-throughput sequencing. Given this fact, NGS is a useful tool for reverse phenotyping, especially for rare diseases. We hereby present two similarly affected siblings with neurodevelopmental delay. Duo-whole exome sequencing was performed. The homozygous LSM1 variant was found as the most likely cause for the condition. Our report contributes to the literature on the phenotype the biallelic LSM1 mutations. Moreover, we highlight the importance of reverse phenotyping and reanalysis of the genetic data.

Specific early signs and long-term follow-up findings of progressive pseudorheumatoid dysplasia (PPRD) in the Turkish cohort.

OBJECTIVES: Progressive pseudorheumatoid dysplasia (PPRD) is a spondyloepiphyseal dysplasia caused by biallelic variants in CCN6. This study aimed to describe the early signs and follow-up findings in 44 Turkish PPRD patients. METHODS: The patients with progressive stiffness of multiple joints, characteristic wide metaphysis of interphalangeal (IP) joints and platyspondyly were clinically diagnosed with PPRD. Fifteen patients who had first symptoms under 3 years of age were grouped as early-onset, while others were grouped as classical. CCN6 sequencing was performed in 43 patients. RESULTS: Thirteen pathogenic/likely pathogenic variants were identified, five were novel. c.156C>A(p.Cys52*) variant was found in 53.3% of the families. The initial symptom in the early-onset group was genu varum deformity, while it was widening of IP joints in the classical group. The median age of onset of symptoms and of diagnosis was 4 and 9.7 years, respectively. The mean follow-up duration was 5.6 years. The median age of onset of IP, elbow, knee and hip stiffness, which became progressive with growth was 5, 9, 9 and 12.2 years, respectively. Waddling gait occurred in 97.7% of the patients. A total of 47.7% lost independent walking ability at the median age of 12 years. In the early-onset group, waddling gait occurred earlier than in classical group (P < 0.001). Two patients had atypical presentation with late-onset and mild or lack of IP involvement. CONCLUSION: We observed that genu varum deformity before the age of 3 years was an early sign for PPRD and almost half of the patients lost walking ability at the median age of 12 years.

Propolis Extract Regulates microRNA Expression in Glioblastoma and Brain Cancer Stem Cells.

BACKGROUND: Grade IV gliomas are classified as glioblastoma (GBM), which is the most malignant brain cancer type. Various genetic and epigenetic mechanisms play a role in the initiation and progression of GBM. MicroRNAs (miRNAs) are small, non-coding RNA molecules that belong to the main epigenetic regulatory RNA class that plays different roles in either physiological or pathological conditions, including GBM pathogenesis regulating expression levels of the target genes. Brain Cancer Stem Cells (BCSCs) are responsible for poor prognosis, including therapy resistance and relapse. Epigenetic regulation mediated by miRNAs is also a critical component of BCSC selfrenewal and differentiation properties. Propolis is a resinous substance collected by honey bees from various plant sources. The flavonoid content of propolis varies depending on the collection region and the extraction method. Although there are studies that include the effects of different originated-propolis on the miRNA expression levels of the glioblastoma cells, the impact on the BCSCs has not been studied yet. OBJECTIVE: This study aims to evaluate the effects of propolis obtained from Aydin, a city in western Turkey, on miRNA expression levels of BCSCs and GBM cells. METHODS: Aydin propolis was dissolved in 60% ethanol, and after evaporation, distilled water was added to prepare the propolis stock solution. The flavonoids content of the Aydin propolis was determined by MS Q-TOF analysis. Commercially obtained U87MG and BCSCs were used as in-vitro brain cancer models. Cytotoxic and apoptotic effects of Aydin propolis were determined via WST-1 assay and Annexin V test, respectively. The miRNA expression profile was investigated using the real-time qRT-PCR method. The fold changes were calculated by the2-ΔΔCt method. The miRNA-mRNA-pathway interactions, including significantly altered miRNAs, were determined using different bioinformatics tools and databases. RESULTS: Quercetin 3-methyl ether was the main component of the Aydin propolis. Aydin propolis did not show significant cytotoxic and apoptotic effects on both GBM and BCSCs up to 2mg/ml concentration. Aydin propolis treatment decreased the expression of nine miRNAs in the U87MG and five miRNAs in the BCSCs. Moreover, ten miRNAs have upregulated from 2.22 to 10.56 folds in propolis treated GBM cells compared to the control group significantly (p<0.05). In the study, the potential roles of two new miRNAs, whose regulations in glioma were not previously defined, were identified. One of them was miR-30d-5p, a novel potential oncomiR in GBM, which was 2.46 folds downregulated in Aydin propolis treated GBM cells. The other one is miR-335-5p, which is a potential tumor suppressor miR in GBM, that was 5.66 folds upregulated in Aydin propolis treated GBM cells. FOXO pathway, its upstream and downstream regulators, and critically neuronal developmental regulators, NOTCH and WNT pathways, were determined as the most deregulated pathways in Aydin propolis treated cells. CONCLUSION: The determination of the anti-cancer effect of Aydin propolis on the miRNA expression of GBM, especially on cancer stem cells, may contribute to the elucidation of brain cancer genetics by supporting further analyses.

Combined immunodeficiency with marginal zone lymphoma due to a novel homozygous mutation in IL-21R gene and successful treatment with hematopoietic stem cell transplantation.

Mutations in the interleukin-21 receptor (IL-21R) gene are recently defined as primary immunodeficiency diseases. IL-21R defects result in combined immunodeficiency by affecting the functions of innate and adaptive immune system components.A six-year-old girl was admitted to our hospital with complaints of chronic diarrhea that started after the newborn period and generalized rash over the last three months. She had severe respiratory distress due to Cytomegalovirus (CMV) pneumonia requiring mechanical ventilation and was diagnosed as combined immunodeficiency at another hospital at the age of four. Her physical examination on admission revealed erythematous rash on cheeks, extremities, gluteal region, and lymph node enlargements in cervical, axillary, and inguinal regions. CMV DNA and stool Cryptosporidium parvum were positive. Marginal zone lymphoma -negative for Epstein-Bar virus- was reported in the lymph node biopsy. Targeted next-generation sequencing Ion AmpliSeq™ primary immunodeficiency panel revealed a novel homozygous IL21R c.132delC (p.Ser45fs) mutation.This case is presented to emphasize that IL21R defects should be considered in the differential diagnosis of the patients with recurrent respiratory infections, chronic diarrhea, C. parvum infection, chronic liver disease, sclerosing cholangitis, and malignancy where early hematopoietic stem cell transplantation (HSCT) is life-saving. A total of eight cases with IL21R gene defects have been reported so far. The significance of this case is that it is the first case of malignancy among the published IL-21R deficient patients successfully treated with HSCT.

A Novel Homozygous TRNT1 Mutation in a Child With an Early Diagnosis of Common Variable Immunodeficiency Leading to Mild Hypogammaglobulinemia and Hemolytic Anemia.

Although sideroblastic anemias (SAs) may be associated with different etiologies, deterioration of mitochondrial heme biosynthesis in bone marrow erythroid cells is a general abnormality. Congenital SA associated with immunodeficiency, periodic fever, and developmental delay is because of loss-of-function mutations in the TRNT1 gene. We report a patient with a novel homozygous mutation in the TRNT1 gene presenting with anemia with siderocytes, hypogammaglobulinemia, hepatosplenomegaly, and brittle hair but without periodic fever or developmental delay. The patient was presented to emphasize the power of reverse phenotyping in the differential diagnosis of primary immunodeficiency patients with atypical features and to raise awareness for TRNT1 disease in case of coexistent SA and hypogammaglobulinemia.

Association of mutation in PTPN14 gene and gingival fibromatosis with distinctive facies: a novel finding in whole exome sequencing.

Gingival fibromatosis with distinctive facies presents a rare clinical picture. It is characterized by gingival fibromatosis in conjunction with some craniofacial dysmorphic features such as relative macrocephaly, bushy eyebrows, synophrys, hypertelorism, downslanting palpebral fissures, flattened nasal bridge, hypoplastic nares, cupid-bow mouth and a high palate. Autosomal recessive inheritance has been suggested. However, to date, no causative gene has been reported. Herein, we report a case presenting with the typical findings of this rare genetic syndrome. A homozygous c.1855C>T (p.Gln619Ter) mutation in the PTPN14 gene was identified.

Recurrent infections, neurologic signs, low serum uric acid levels, and lymphopenia in childhood: Purine nucleoside phosphorylase deficiency, an emergency for infants.

Purine nucleoside phosphorylase deficiency is one of the severe combined immunodeficiencies, which often clinically manifests with recurrent infections, neurologic symptoms and autoimmune diseases, and leads to thymocyte development and peripheral T cell activation defects. It is an immunologic emergency for childhood. In this case series, four cases with purine nucleoside phosphorylase deficiency were evaluated. Recurrent febrile infections and neuromotor developmental retardation were among the presenting symptoms in all cases. Absolute lymphocyte counts and serum uric acid levels were very low, and serum immunoglobulin levels were normal or slightly lower in all cases. The genetic molecular analysis of four patients revealed three predefined mutations in the purine nucleoside phosphorylase gene. Three of the four patients were lost due to sepsis during follow-up, and one patient was lost due to veno-occlusive disease in the post-hematopoietic stem cell transplantation period. We presented these cases to emphasize that purine nucleoside phosphorylase deficiency should always be considered in patients with frequent recurrent infections, neurologic findings, low serum uric acid levels, and lymphopenia.

Detection of SHOX Gene Variations in Patients with Skeletal Abnormalities with or without Short Stature

Objective: SHOX gene mutations constitute one of the genetic causes of short stature. The clinical phenotype includes variable degrees of growth impairment, such as Langer mesomelic dysplasia (LMD), Léri-Weill dyschondrosteosis (LWD) or idiopathic short stature (ISS). The aim of this study was to describe the clinical features and molecular results of SHOX deficiency in a group of Turkish patients who had skeletal findings with and without short stature. Methods: Forty-six patients with ISS, disproportionate short stature or skeletal findings without short stature from 35 different families were included. SHOX gene analysis was performed using Sanger sequencing and multiplex ligation-dependent probe amplification analysis. Results: Three different point mutations (two nonsense, one frameshift) and one whole SHOX gene deletion were detected in 15 patients from four different families. While 4/15 patients had LMD, the remaining patients had clinical features compatible with LWD. Madelung's deformity, cubitus valgus, muscular hypertrophy and short forearm were the most common phenotypic features, as well as short stature. Additionally, hearing loss was detected in two patients with LMD. Conclusion: This study has presented the clinical spectrum and molecular findings of 15 patients with SHOX gene mutations or deletions. SHOX deficiency should be especially considered in patients who have disproportionate short stature or forearm anomalies with or without short stature. Although most of the patients had partial or whole gene deletions, SHOX gene sequencing should be performed in suspected cases. Furthermore, conductive hearing loss may rarely accompany these clinical manifestations.

Clinical and molecular aspects of PTEN mutations in 10 pediatric patients.

INTRODUCTION: PTEN gene mutations are responsible for the PTEN hamartoma tumor syndrome (PHTS). In this study, clinical and molecular findings of patients carrying PTEN mutations are presented. Our aim is to contribute to genotype-phenotype correlation and define the most common findings of the syndrome in pediatric patients. METHODS AND MATERIALS: Ten molecularly confirmed PHTS patients from seven families were included in the study. All patients were examined by a clinical geneticist. Laboratory test results were obtained from hospital records. Sequencing of PTEN gene was performed. Variant interpretation was done in accordance with 2015 recommendations from the American College of Medical Genetics. RESULTS: Macrocephaly was the most common clinical finding, involving all patients. This was followed by skin lesions, neurodevelopmental delay, and pathologic cranial magnetic resonance imaging findings. Seven different heterozygous PTEN gene variants were found in seven families. Four of these were located in exon 5, which has been described as a hot spot area for the PTEN gene. Four mutations were novel. A wide range of phenotypic and genotypic spectra was found in our study group. CONCLUSION: Screening of PTEN mutations in patients with macrocephaly is recommended due to an increased risk of cancer. Further cases are needed to make a phenotype-genotype correlation in PHTS.

Concordance in molecular genetic analysis of tumour tissue, plasma, and exhaled breath condensate samples from lung cancer patients.

AIM: Lung adenocarcinoma is characterized by poor prognosis and short survival rates. Therefore, tools to identify the tumoural molecular structure and guide effective diagnosis and therapy decisions are essential. Surgical biopsies are highly invasive and not conducive for patient follow-up. To better understand disease prognosis, novel non-invasive analytic methods are needed. The aim of the present study is to identify the genetic mutations in formalin-fixed paraffin-embedded (FFPE) tissue, plasma, and exhaled breath condensate (EBC) samples by next-generation sequencing and evaluate their utility in the diagnosis and follow-up of patients with lung adenocarcinoma. METHOD: FFPE, plasma, and EBC samples were collected from 12 lung adenocarcinoma patients before treatment. DNA was extracted from the specimens using an Invitrogen PureLink Genomic DNA Kit according to the manufacturer's instructions. Amplicon-based sequencing was performed using Ion AmpliSeq Colon and Lung Cancer Research Panel v2. RESULTS: Genetic alterations were detected in all FFPE, plasma, and EBC specimens. The mutations in PIK3CA, MET, PTEN, SMAD4, and FGFR2 genes were highly correlated in six patients. Somatic and novel mutations detected in tissue and EBC samples were highly correlated in one additional patient. The EGFR p.L858R and KRAS p.G12C driver mutations were found in both the FFPE tissue specimens and the corresponding EBC samples of the lung adenocarcinoma patients. CONCLUSION: The driver mutations were detected in EBC samples from lung adenocarcinoma patients. The analysis of EBC samples represents a promising non-invasive method to detect mutations in lung cancer and guide diagnosis and follow-up.

Fetal Gene Therapy Using a Single Injection of Recombinant AAV9 Rescued SMA Phenotype in Mice.

Symptoms of spinal muscular atrophy (SMA) disease typically begin in the late prenatal or the early postnatal period of life. The intrauterine (IU) correction of gene expression, fetal gene therapy, could offer effective gene therapy approach for early onset diseases. Hence, the overall goal of this study was to investigate the efficacy of human survival motor neuron (hSMN) gene expression after IU delivery in SMA mouse embryos. First, we found that IU-intracerebroventricular (i.c.v.) injection of adeno-associated virus serotype-9 (AAV9)-EGFP led to extensive expression of EGFP protein in different parts of the CNS with a great number of transduced neural stem cells. Then, to implement the fetal gene therapy, mouse fetuses received a single i.c.v. injection of a single-stranded (ss) or self-complementary (sc) AAV9-SMN vector that led to a lifespan of 93 (median of 63) or 171 (median 105) days for SMA mice. The muscle pathology and number of the motor neurons also improved in both study groups, with slightly better results coming from scAAV treatment. Consequently, fetal gene therapy may provide an alternative therapeutic approach for treating inherited diseases such as SMA that lead to prenatal death or lifelong irreversible damage.

Chronic granulamatous disease: Two decades of experience from a paediatric immunology unit in a country with high rate of consangineous marriages.

Chronic granulomatous disease (CGD) is a primary immunodeficiency characterized by susceptibility to bacterial and fungal infections resulting from the inadequacy of phagocytic leucocytes to produce reactive oxygen radicals. CGD is a genetically heterogeneous disease with an X-linked recessive (XR-CGD) form caused by mutations in the CYBB (OMIM #300481) gene encoding the gp91(phox) protein, and an autosomal recessive (AR-CGD) form caused by mutations in the CYBA (OMIM #608508), NCF1 (OMIM #608512), NCF2 (OMIM #608515) and NCF4 (OMIM #601488) genes encoding p22(phox), p47(phox), p67(phox) and p40(phox), respectively. The genetic mutation of one of the cytosolic p47phox/p67phox proteins and membrane-bound gp91phox/p22phox proteins, which constitutes the NADPH oxidase enzyme complex, causes the disease. In this study, we evaluated the clinical, laboratory and genetic findings and the prognostic effects of molecular inheritance of our 24 CGD cases (14 XR, 10 autosomal recessive-AR). Consanguinity (three XR and all AR cases) showed statistically significant relationship with the type of hereditary inheritance (P < 0.001). 83% patients had an infection since early infancy. The mean age of initiation of symptoms was earlier in XR cases, and 78% patients had respiratory tract infections. Bone marrow transplantation was performed in five XR cases (two ex) and four AR (one ex) cases. Three of nine XR and two of six AR cases deceased on medical follow-up. In countries especially with high consanguinity rates, the early diagnosis for appropriate prophylactic treatment of CGD is quietly important to avoid from recurrent severe infections, early death and fatal complications of late transplantation.

Evaluation of CNTNAP2 gene rs2107856 polymorphism in Turkish population with pseudoexfoliation syndrome.

PURPOSE: To investigate rs2107856 single-nucleotide polymorphism (SNP) of CNTNAP2 gene in Turkish population with pseudoexfoliation and to correlate clinical characteristics with the genotypic profile. MATERIALS AND METHODS: Forty-three patients with pseudoexfoliation syndrome (PXS), 46 patients with pseudoexfoliation glaucoma (PXG) and 99 healthy controls were enrolled. Comprehensive ophthalmological examination, central corneal thickness measurement and retinal nerve fiber layer thickness analysis of the peripapillary area were performed. Blood samples of 2 mL with EDTA were obtained and sent for genetic analysis. The role of the detected polymorphism on disease tendency along with the genotype and allele frequencies in each group was evaluated. RESULTS: The mean age of the groups was 70.0 ± 8.0 (range 51-86) in PXS, 71.2 ± 8.8 (range 51-93) in PXG and 64.6 ± 8.3 (range 51-91) in controls. The percentages of homozygote individuals were 11.6, 10.9, 21.2%, and heterozygote individuals were 41.9, 45.7, 42.4% in patients with PXS, PXG and controls, respectively. There was no statistically significant difference between groups in terms of both genotype and allele frequencies of rs2107856 (p = 0.429 and p = 0.178, respectively). Retinal nerve fiber layer thickness did not differ between SNP-positive and SNP-negative individuals in PXG, and there was no significant difference between genotype and age, sex, best corrected visual acuity, intraocular pressure, central corneal thickness, cup/disk ratio and retinal nerve fiber layer thickness in any of the groups (p > 0.05). CONCLUSION: rs2107856 SNP of CNTNAP2 gene has no association with PXS and PXG in the evaluated Turkish population.

An X-Linked Hyper-IgM Patient Followed Successfully for 23 Years without Hematopoietic Stem Cell Transplantation.

When caring for patients with life-limiting diseases, improving survival and optimizing quality of life are the primary goals. For patients with X-linked hyper-IgM syndrome (XHIGM), the treatment modality has to be decided for a particular patient regarding hematopoietic stem cell transplantation or intravenous immunoglobulin replacement therapy with P. jiroveci prophylaxis. A seven-year-old male patient was admitted with recurrent upper and lower respiratory tract infections and recurrent otitis media. His initial immunologic evaluation revealed low IgG and normal IgA and IgM levels with normal lymphocyte phenotyping and inadequate specific antibody responses. He was diagnosed as common variable immunodeficiency and began to receive intravenous immunoglobulin (IVIG) (0.5 gm/kg) with four-week intervals. During follow-up for 23 years under IVIG therapy, he was extremely well and never had severe infections. In 2017, targeted next generation sequencing was performed in order to understand his molecular pathology. A previously described hemizygous c.31C>T(p.Arg11Ter) mutation was found in CD40LG gene. The mother was heterozygous carrier for this mutation and his sister did not have any mutation. Flow cytometric analysis for CD40LG expression on activated T cells showed highly decreased, but not absent, CD40LG expression. In conclusion, diagnostic delay is a clinical problem for patients with CD40LG deficiency, because of low or normal IgM levels, showing that all the hypogammaglobulinemic patients, not only with high serum IgM levels, but also with normal to low IgM levels, have to be examined for CD40LG expression on activated T lymphocytes. Secondly, type of CD40LG mutations leads to enormous interpatient variations regarding serum IgM levels, CD40LG levels on activated T cells, age at diagnosis, severity of clinical findings, and follow-up therapies with or without hematopoietic stem cell therapy.

Two Childhood Pheochromocytoma Cases due to von Hippel-Lindau Disease, One Associated with Pancreatic Neuroendocrine Tumor: A Very Rare Manifestation

von Hippel-Lindau (VHL) disease is an autosomal dominantly inherited disorder, characterized by hemangioblastomas of the retina and central nervous system (CNS); renal cysts; clear cell carcinoma; pheochromocytoma (PCC); endolymphatic sac tumors; cystadenomas of the epididymis in males; broad ligament of uterus in females; pancreatic cysts; cystadenomas; and neuroendocrine tumors. We report two cases of VHL disease that presented with PCC as the first manifestation. Further clinical developments during follow-up, hemangioblastoma of CNS in one case and a pancreatic neuroendocrine tumor (PNET) in the second case led to the diagnosis of VHL disease. Genetic analyses of the two cases revealed p.Arg161Gln (c.482G>A) and p.Leu129Pro (c.386T>G) heterozygous missense mutations in the VHL gene, respectively. In children, PCC may be the only and/or initial manifestation of VHL with delayed manifestations of the syndrome in other organs. PNET is a very rare manifestation of VHL disease. To the best of our knowledge, this is only the second reported case presenting with a combination of a PNET and bilateral PCC as components of childhood VHL disease. Pediatric patients diagnosed with PCC should be investigated for genetic causes and especially for VHL.

HAX1 mutation positive children presenting with haemophagocytic lymphohistiocytosis.

The genetic basis of haemophagocytic lymphohistiocytosis (HLH) has not been elucidated in 10% of affected patients. In this study, we report four HLH episodes in three patients with HAX1 gene mutations. We screened the mutations associated with congenital neutropenia (CN) because the neutropenia persisted following HLH treatment. There were homozygous HAX1 mutations detected in all patients. This is the first case series of patients with CN caused by HAX1 mutation who presented with HLH. We hypothesize that severe neutropenia persists after an HLH episode in children without HLH mutations (especially infants) because these patients have CN caused by HAX1 mutations.