Genetic Workup Research Articles

Clinical characterization and identification of rare genetic variants in atypical hemolytic uremic syndrome: A Swedish retrospective observational study.

Complement-mediated atypical hemolytic uremic syndrome (aHUS) is an ultra-rare renal disease primarily caused by genetic alterations in complement proteins. The genetic work-up required for confirmation of diagnosis is complicated and not always logistically accessible. The aim of the present study was to apply a diagnostic scheme compliant with the American College of Medical Genetics and Genomics guidelines to investigate the prevalence of complement-mediated aHUS among subjects formerly included in a retrospective cohort of clinically suspected aHUS. Clinical outcomes and genetic correlations to complement analyses were assessed. Subjects were investigated with medical record reviewing, inquiries, and laboratory analyses composed of whole genome sequencing; enzyme-linked immunosorbent assays for factor I, factor H, and factor H-specific antibodies; nephelometry for complement components three of four; flow cytometry for CD46 surface expression and immunoblotting for the presence of factor H-related protein 1. In total, 45% (n= 60/134) of the subjects were deceased at the time of study. Twenty of the eligible subjects consented to study participation. Based on genetic sequencing and clinical characteristics, six were categorized as definite/highly suspected complement-mediated aHUS, 10 as non-complement-mediated aHUS and four as having an HUS-like phenotype. In the complement-mediated aHUS group, two subjects had not received an aHUS diagnosis during the routine clinical management. Disease-contributing/likely disease-contributing genetic variants were identified in five subjects, including a novel missense variant in the complement factor H gene (c.3450A>G, p.I1150M). This study illustrates the risk for misdiagnosis in the management of patients with complement-mediated aHUS and the importance of a comprehensive assessment of both phenotype and genotype to reach a diagnosis.

41. Clinical significance of comprehensive genetic workup prior to use of assisted reproductive technology: A case study

A 16-month-old female was seen at the genetics clinic due to hypotonia and significant developmental delay. The proband was the product of a twin pregnancy. Chromosome analysis as well as fragile X, Prader Willi and Angelman tests were all normal. Whole-genome microarray analysis revealed a 4.6 Mb interstitial copy number gain involving the distal part of the long arm of chromosome 3q28-q29 (chr3:190800735_195464853). Confirmatory metaphase FISH as well as whole-chromosome paint FISH revealed that the duplicated 3q28-q29 material is not tandem but rather inserted into the proximal long arm of chromosome 9, resulting in 46,XX,ins(9;3)(q21.2;q28q29). In order to determine the origin of this abnormality, FISH was performed on parental specimens. To our surprise, the maternal interphase FISH analysis revealed the loss of the 3q region. However, review of the metaphase FISH and subsequently maternal karyotype indicated that the deleted 3q region was in fact involved in an apparently unbalanced translocation between chromosomes 1 and 3 resulting in 46,XX,der(1)t(1;3)(q25.2;q28),der(3)?del(3)(q29)t(1;3). It is unclear how a maternal unbalanced translocation involving chromosomes 1 and 3 with a net loss of the 3q region, could result in an insertion-duplication involving chromosome 3 and 9. This seemingly unusual finding prompted further investigation which revealed that the pregnancy was achieved via IVF using both the mother's as well as related donor oocytes i.e. the maternal aunt's. Reportedly, three embryos were transferred, only one of which was derived from maternal oocyte. It is therefore plausible that the maternal aunt would be the carrier of a related rearrangement e.g. a balanced insertion. Follow up familial analyses are underway and will be discussed with the audience. This case highlights the significance of comprehensive genetic workup prior to the utilization of assisted reproductive technology, even in the absence of phenotypic anomalies in the parents.

Genetic and Non-genetic Workup for Pediatric Congenital Hearing Loss.

Hearing loss is one of the most common concerns for presentation for a geneticist. Presentation prior to the age of one (congenital hearing loss), profound sensorineural hearing loss (SNHL), and bilateral hearing loss are sensitive and should raise concern for genetic causes of hearing loss and prompt referral for genetic testing. Genetic testing particularly in this instance offers the opportunity for anticipatory guidance including possible course of the hearing loss over time and also connection and evaluation for additional congenital anomalies that may be associated with an underlying syndrome vs. isolated genetic hearing loss.

Arching deep brain stimulation in dystonia types.

Although medical treatment including botulinum toxic injection is the first-line treatment for dystonia, response is insufficient in many patients. In these patients, deep brain stimulation (DBS) can provide significant clinical improvement. Mounting evidence indicates that DBS is an effective and safe treatment for dystonia, especially for idiopathic and inherited isolated generalized/segmental dystonia, including DYT-TOR1A. Other inherited dystonia and acquired dystonia also respond to DBS to varying degrees. For Meige syndrome (craniofacial dystonia), other focal dystonia, and some rare inherited dystonia, further evidences are still needed to evaluate the role of DBS. Because short disease duration at DBS surgery and absence of fixed musculoskeletal deformity are associated with better outcome, DBS should be considered as early as possible when indicated after careful evaluation including genetic work-up. This review will focus on the factors to be considered in DBS for patients with dystonia and the outcome of DBS in the different types of dystonia.

Effective identification of cancer predisposition syndromes in children with cancer employing a questionnaire

Approximately 10% of children with newly diagnosed cancer have a cancer predisposition syndrome (CPS). The optimal diagnostic approach to identify them among children diagnosed with cancer is unknown. Objective: To determine whether the use of a one-page questionnaire can improve the CPS diagnosis among children with an oncologic condition. Design: Comparative effectiveness research. Setting: Referral center for children with cancer. Results: 739 children diagnosed with an oncologic condition between 2012 and 2019. All children with a newly diagnosed oncologic condition presenting to Hannover Medical School between January 1st 2017 and December 31st 2019 were prospectively evaluated with a CPS questionnaire. Children in whom the questionnaire suggested the need of a genetic workup were further evaluated. All children diagnosed with an oncologic condition between January 1st 2012 and December 31st 2016 served as control. The CPS diagnoses established during both time periods were evaluated and compared. A CPS was diagnosed in 27 out of 287 children (9.4%) during the questionnaire period versus 24 out of 452 children (5.3%) during the control period (P = 0.032). Conclusion: The CPS questionnaire appears to significantly improve the diagnosis of children with CPS among children with a newly diagnosed oncologic condition.

Congenital Chylothorax and Hydrops Fetalis: A Novel Neonatal Presentation of RASA1 Mutation

Mutations in the RASA1 gene are known to cause arteriovenous malformations (AVMs), with evidence of associated lymphatic malformations. We report for the first time, to the best of our knowledge, an infant with RASA1 mutation presenting with hydrops fetalis and chylothorax, but without an associated AVM. Previously, researchers studying rodents have found chylothorax associated with RASA1 mutations, and, in previous case reports, researchers have reported on infants with RASA1 mutations born with hydrops fetalis and AVMs. In this report, we describe the case of a "late preterm" female infant born with nonimmune hydrops fetalis and congenital chylothorax who was detected to have a RASA1 deletion on genetic workup. Although classically described phenotypes of RASA1 mutations present with venous malformations, no such malformations were found in this infant on extensive imaging. This combination is a novel and nonclassic presentation of RASA1 mutation. In cases of congenital chylothorax, especially with nonimmune hydrops fetalis, RASA1 mutations should be considered as part of the differential diagnosis and genetic testing should be included as part of a complete workup to allow for screening for associated vascular anomalies.

63 Hydrops-Yielding Diagnostic Results Of Prenatal Exome Sequencing (HYDROPS) Trial - Prenatal WES for NIHF

NIHF can be caused by multiple etiologies. Standard genetic workup evaluates chromosomal and a few monogenic disorders. We explored the utility of prenatal exome sequencing (ES) for NIHF after a complete negative standard workup. Participants enrolled prospectively in the Hydrops-Yielding Diagnostic Results of Prenatal Sequencing (HYDROPS) trial from MFM practices across the country (14 states). We used a strict phenotypic description for NIHF diagnosis, including at least two of the following: skin edema, ascites, pleural effusion, or pericardial effusion. The negative standard workup includes testing for infection (parvovirus, CMV, toxoplasmosis, syphilis), fetal-maternal hemorrhage (Kleihauer-Betke test or MCA Doppler), and chromosomal disorders (microarray). Trio ES from fetal samples and parental blood was performed at a CLIA-certified laboratory with reports returned by genetic counselors. Exomes were reanalyzed with information from subsequent ultrasounds and records. Twenty-two fetal exomes were analyzed with 11 (50%) diagnostic results and five possible diagnoses (22.7%). Diagnosed cases included seven de novo dominant disorders, three recessive disorders, and one inherited dominant disorder including four Noonan syndromes (PTPN11, RAF1, RIT1, RRAS2), three musculoskeletal disorders (RYR1, AMER1, BICD2), two metabolic disorders (sialidosis, multiple sulfatase deficiency), one Kabuki syndrome, and one congenital anemia (KLF1). Five cases with “Possible Diagnoses” included 3 compound heterozygous VOUS in genes known to cause NIHF (two cases PIEZO1, one case MPS VII) and 2 cases with de novo variants in candidate genes. This included HSPB1, a likely candidate for fetal akinesia and NIHF and NOTCH1 associated with Adams-Oliver syndrome. The etiology of NIHF predicts pregnancy viability, postnatal prognosis, and recurrence risk in future pregnancies. ES has high incremental diagnostic yield for NIHF after standard-of-care testing and should be considered in the workup. Genetic counseling is required for pretest counseling, clear interpretation, and result return.View Large Image Figure ViewerDownload Hi-res image Download (PPT)

MAP3K6 Mutations in a Neurovascular Disease Causing Stroke, Cognitive Impairment, and Tremor.

ObjectiveTo describe a possible novel genetic mechanism for cerebral small vessel disease (cSVD) and stroke.MethodsWe studied a Swedish kindred with ischemic stroke and intracerebral hemorrhage, tremor, dysautonomia, and mild cognitive decline. Members were examined clinically, radiologically, and by histopathology. Genetic workup included whole-exome sequencing (WES) and whole-genome sequencing (WGS) and intrafamilial cosegregation analyses.ResultsFifteen family members were examined clinically. Twelve affected individuals had white matter hyperintensities and 1 or more of (1) stroke episodes, (2) clinically silent lacunar ischemic lesions, and (3) cognitive dysfunction. All affected individuals had tremor and/or atactic gait disturbance. Mild symmetric basal ganglia calcifications were seen in 3 affected members. Postmortem examination of 1 affected member showed pathologic alterations in both small and large arteries the brain. Skin biopsies of 3 affected members showed extracellular amorphous deposits within the subepidermal zone, which may represent degenerated arterioles. WES or WGS did not reveal any potentially disease-causing variants in known genes for cSVDs or idiopathic basal ganglia calcification, but identified 1 heterozygous variant, NM_004672.4 MAP3K6 c.322G>A p.(Asp108Asn), that cosegregated with the disease in this large family. MAP3K6 has known functions in angiogenesis and affects vascular endothelial growth factor expression, which may be implicated in cerebrovascular disease.ConclusionsOur data strongly suggest the MAP3K6 variant to be causative for this novel disease phenotype, but the absence of functional data and the present lack of additional families with this disease and MAP3K6 mutations still limit the formal evidence for the variant's pathogenicity.

Head and neck paragangliomas in Norway, importance of genetics, updated diagnostic workup and treatment

Background Head and neck paragangliomas (HNPG) are rare and predominantly benign tumours, originating from the neuroendocrine paraganglionic system. A considerable proportion of HNPGs are hereditary, depending on the population. Aims/objectives The purpose of this study was to estimate the rate of hereditary HNPGs in a Scandinavian (Norwegian) population, report long-term experience with HNPGs and offer all patients diagnosed an updated follow-up, with emphasis on identifying hereditary HNPGs through genetic screening and multifocality by 18 F-2-fluorodeoxyglucose positron emission tomography/computed tomography (18F-FDG PET/CT). Material and methods Our study was a partly retrospective and partly prospective cohort study. It included patients with HNPG diagnosed at Oslo University Hospital (OUH), Rikshospitalet between 1990 and 2017. The patients underwent genetic testing, 18F-FDG PET/CT and measurement of catecholamines and meta-nephrines in the plasma. All resection specimens and biopsies were subjected to histopathological review. The genetic testing protocol consisted of testing for mutations in the following genes; SDHD, SDHB, SDHC, VHL and RET. Results Sixty-three patients were included in the study with a median age of 49 years (range 12 − 80). Cranial nerve dysfunction was present upon diagnosis in 13%, and 14% had multifocal paraganglioma (PG) disease. Fifty-six patients (89% of all the patients) underwent genetic testing, and 29% of these had a PG related mutation. Seven of the eight patients (88%) with multifocal PGs who underwent genetic testing had a mutation. In two of the patients, the 18F-FDG PET/CT revealed unknown and subclinical multifocality. Conclusions and significance This is the first study with systematic genetic workup and PET/CT imaging in Scandinavia of HNPG patients. The mutation rate was within the lower range reported in the literature with respect to HNPGs. Combining genetic testing and PET/CT imaging in the diagnostic workup of HNPGs is valuable.

15510 A perfect storm: Multiple genetic mutations in a patient with type 1 neurofibromatosis leading to 14 primary malignant melanomas

Introduction: The neurofibromin 1 gene is a tumor suppressor and its loss is frequently reported in sporadic cases of melanoma. Both melanocytes and peripheral nerves are derived from neural crest cells, thus a theoretical risk of melanoma development exists in patients with type 1 neurofibromatosis (NF1). However in reality, the incidence of malignant melanoma in NF1 patients is rare, and is only described in scattered case reports. This case describes the development of 14 primary malignant melanoma tumors in a patient with NF1. His genetic work-up elucidates combinations of genetic mutations present which may predispose to melanoma development.

Texture analysis of T2-weighted MRI predicts SDH mutation in paraganglioma.

Texture analysis can quantify sophisticated imaging characteristics. We hypothesized that 2D textures computed with T2-weighted and post-contrast T1-weighted MRI can predict succinate dehydrogenase (SDH) mutation status in head and neck paragangliomas. Our retrospective study included 21 patients (1 to 4 tumors/patient) with 24 pathologically proven paragangliomas in the head and neck. Fourteen lesions (58%) were SDH mutation-positive. All patients underwent T2-weighted and post-contrast T1-weighted MRI sequences. Three 2D texture features of dependence non-uniformity normalized (DNN), small dependence high gray level emphasis (SDHGLE), and small dependence low gray level emphasis (SDLGLE) were calculated. Computed textures between SDH mutants and non-mutants were compared using Mann-Whitney U test. Area under the receiver operating characteristic (AUROC) curve was used to quantify the predictive power of each texture. Only T2-based SDLGLE was statistically significant (p = 0.048), and AUROC was 0.71. Diagnostic accuracy was 70.8%. 2D texture parameter of T2-based SDLGLE predicts SDH mutation in head and neck paragangliomas. This noninvasive technique can potentially facilitate further genetic workup.

Hereditary Disorders of Cardiovascular Calcification.

Arterial calcification is a common phenomenon in the elderly, in patients with atherosclerosis or renal failure and in diabetes. However, when present in very young individuals, it is likely to be associated with an underlying hereditary disorder of arterial calcification. Here, we present an overview of the few monogenic disorders presenting with early-onset cardiovascular calcification. These disorders can be classified according to the function of the respective disease gene into (1) disorders caused by an altered purine and phosphate/pyrophosphate metabolism, (2) interferonopathies, and (3) Gaucher disease. The finding of arterial calcification in early life should alert the clinician and prompt further genetic work-up to define the underlying genetic defect, to establish the correct diagnosis, and to enable appropriate therapy.

Hidden etiology of cerebral palsy: genetic and clinical heterogeneity and efficient diagnosis by next-generation sequencing.

Cerebral palsy (CP) is a heterogeneous neurodevelopmental disorder that causes movement and postural disabilities. Recent research studies focused on genetic diagnosis in patients with CP of unknown etiology. The present study was carried out in 20 families with one family member affected with idiopathic CP. Chromosomal microarray and exome sequencing techniques were performed in all patients. Chromosomal microarray analysis did not show any pathological or probable pathological structural variant. However, the next-generation sequencing study showed a high diagnostic yield. We report 11/20 patients (55%) with different pathogenic or potentially pathogenic variants detected by exome sequencing analysis: five patients with mutations in genes related to hereditary spastic paraplegia, two with mutations in genes related to Aicardi-Goutières syndrome, three with mutations in genes related to developmental/epileptic encephalopathies, and one with a mutation in the PGK1 gene. The accurate and precise patients' selection, the use of a high-throughput genetic platform, the selection of adequate target genes, and the application of rigorous criteria for the clinical interpretation are the most important elements for a good diagnostic performance. Based on our findings, next-generation sequencing should be considered in patients with cryptogenic CP as the first line of genetic workup. IMPACT: Sequencing techniques in CP of uncertain etiology provides a diagnostic yield of 55%. The appropriate selection of cases optimizes the diagnostic yield. NGS facilitate better understanding of new phenotypes of certain genetic diseases.

Hereditary Spherocytosis Due to a Novel Variant, P.Q1034X, in the Beta Subunit of the Spectrin Gene

Introduction: Hereditary Spherocytosis (HS) is the most common red cell membrane disorder. 25-30% of cases involve the SPTB gene which encodes for β-Spectrin, a protein that maintains red blood cell shape. Heterozygous variants in SPTB are associated with autosomal dominant HS and elliptocytosis. While genetic testing is not routinely done to confirm HS, it is useful in atypical presentations. Case Description: A 1 week old male presented to the pediatric hematology/oncology clinic for anemia. He was born late preterm and had a history of hyperbilirubinemia requiring phototherapy, failure to thrive, and developmental delay. On examination, he was noted to have hypotonia. There was no known family history of hematologic problems. Based on this constellation of signs and symptoms, he had a comprehensive hematologic and genetic workup. On lab evaluation, his peripheral blood smear showed normocytic normochromic red blood cells with some spherocytes, significant polychromasia, normal WBC and normal platelet morphology. His newborn screen was normal, direct coombs' negative, osmotic fragility test was positive, and protein band 3 reduction was abnormal. His abdominal ultrasound was normal. Whole exome sequencing with variant segregation analysis was significant for heterozygosity of the p.Q1034X variant of the SPTB gene. This variant in the SPTB gene has not been previously reported. Discussion: We found a novel, de novo variant in an infant with HS through whole exome sequencing. This variant is predicted to cause loss of normal protein function either through protein truncation or non-mediated mRNA decay resulting in fragile red blood cells. While neither parent was found to carry this mutation, germline mosaicism should not be excluded. Physicians should be aware that prenatal diagnosis is available to address the risk of recurrence in future pregnancies.

NF1 Tumor Suppressor Gene Inactivation in Juvenile Myelomonocytic Leukemia: New Genetic Evidence and Consequences for Diagnostic Work-up

Neurofibromatosis type 1 (NF-1) predisposes to juvenile myelomonocytic leukemia (JMML) via loss of function of the NF1 tumor suppressor gene and consecutive deregulation of Ras signal transduction. Affected individuals usually carry one defective NF1 allele in the germline; somatic inactivation of the second NF1 allele in hematopoietic cells is associated with transformation to leukemia. We previously demonstrated that a major mechanism for biallelic loss of NF1 function in patients with JMML/NF-1 is mitotic recombination leading to uniparental disomy (UPD) of the 17q chromosome arm (Flotho, 2007; Steinemann, 2010). Using contemporary resequencing and microarray technology, we have now revisited the genetics of NF1 inactivation in JMML. Specifically, we addressed two questions: 1) Are genetic findings in leukemic cells of JMML/NF-1 patients consistent with the clinical diagnosis and the two-hit concept? 2) Does the quintuple-negative (QN) group of JMML (patients without clinical evidence of NF-1 and negative for mutations in PTPN11, KRAS, NRAS, or CBL) contain unrecognized cases likely driven by NF1? We investigated 156 children with JMML registered in studies EWOG-MDS 98 or 2006 and tested for mutations in PTPN11, KRAS, NRAS, and CBL. Twenty-five children (16%) were clinically diagnosed as NF-1 based on >=6 café-au-lait spots (CALS) or family history plus CALS. Family history was positive in 9 JMML/NF-1 patients; >=6, 4, and 1 CALS were described in 23, 1, and 1 patients, respectively. The median age at diagnosis of JMML in the NF-1 group was 35.9 months (range, 4.2 to 71.4). Sixteen children (10%) were grouped as JMML-QN. Granulocyte DNA from bone marrow or peripheral blood collected at time of diagnosis was used for next-generation sequencing of the entire NF1 coding sequence (custom Ampliseq enrichment and Miseq, Illumina). Pathogenicity of NF1 variants was assessed according to ACMG criteria. Affymetrix Cytoscan HD array analysis was applied to detect segmental deletions or copy number-neutral loss of heterozygosity (LOH). Among 25 JMML/NF-1 cases, 8 exhibited an NF1 loss-of-function mutation at near-100% variant allelic frequency (VAF) in combination with UPD involving almost the entire 17q arm, suggesting single mitotic recombination as the leukemic driver. One case had an NF1 mutation at near-100% VAF and segmental 17q UPD, suggesting the unusual occurrence of double mitotic recombination. Nine cases carried two independent pathogenic NF1 mutations at near-50% VAF each; here, germline and somatic events could not be distinguished due to unavailability of non-hematopoietic or parental DNA. Four cases exhibited an NF1 microdeletion in combination with a pathogenic NF1 mutation at near-100% VAF; non-hematopoietic tissue available in 2 of these 4 cases failed to display the mutation, indicating the microdeletion as the constitutional event. A deleterious mutation at 71% VAF but no LOH was revealed in one sample. Only monoallelic evidence of NF1 deficiency was found in 2 cases. In the JMML-QN group, 9/16 cases had previously unrecognized NF1 alterations. Compound-heterozygous pathogenic NF1 mutations were found in 2 and homozygous pathogenic NF1 mutations combined with focal LOH in 3 patients, strongly suggesting NF1 as the JMML driver. In the absence of clinical NF-1 features, the findings in these 5 children may be explained by postzygotic NF1 mosaicism, onset of JMML before clinical manifestation of NF-1, or double somatic NF1 hits in the hematopoietic lineage. Four cases carried monoallelic pathogenic or likely pathogenic NF1 mutations with VAF at ~50% or less, providing inconclusive evidence of driver function as it is also possible that these are secondary hits in a myeloproliferative neoplasm (MPN) driven by an unidentified event. There was no genetic evidence of NF1 involvement in the remaining 7 JMML-QN cases. Several important conclusions can be drawn from our study: The clinical diagnosis is reliable in children with JMML/NF-1; we propose that it can be made on the basis of CALS and JMML alone as the patients are generally too young to display the conventional spectrum of NF-1 features. Children without features of NF-1 should only be assigned to JMML-QN after genetic work-up of NF1 because this will unmask involvement of NF1 in a significant number of cases. In suspected JMML-QN without identifiable NF1 lesion, other forms of MPN should be considered. Disclosures Locatelli: Jazz Pharmaceeutical: Speakers Bureau; Medac: Speakers Bureau; Miltenyi: Speakers Bureau; Bellicum Pharmaceutical: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Amgen: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Niemeyer:Celgene: Consultancy; Novartis: Consultancy.

A RARE CASE OF PULMONARY NON-LANGERHANS CELL HISTIOCYTOSIS

SESSION TITLE: Medical Student/Resident Lung Pathology SESSION TYPE: Med Student/Res Case Rep Postr PRESENTED ON: October 18-21, 2020 INTRODUCTION: Histiocytic neoplasms are a rare group of heterogeneous disorders which may involve the lung. The most common, Langerhans cell histiocytosis (LCH), is often associated with smoking. Less common are the Non-Langerhans cell histiocytosis, Erdheim-Chester disease (ECD) and Rosai-Dorman disease (RDD). Diagnosis and treatment are often delayed due to lack of proper interpretation of clinical, radiological and histological findings. The following case poses as a diagnostic challenge as the patient is elderly, with no smoking history, and thus falls into an unsuspecting population vulnerable to prolonged invasive workup and missed diagnoses. CASE PRESENTATION: A 75-year-old male, non-smoker, was admitted for evaluation of persistent dyspnea and cough for several weeks despite outpatient treatment with antibiotics. Presented afebrile, and hypoxic requiring 4L/min via nasal cannula. History revealed recurrent pneumonias for several months and persistent infiltrates on CXR. Chest CT showed emphysematous changes with intralobular septae thickening, and bilateral pleural effusions. Thoracentesis was attempted but was unsuccessful due to the thick nature of the aspirate. Following an unyielding bronchoscopy, a subsequent right upper lobe wedge biopsy showed histological features diagnostic of pulmonary histiocytosis. Pleomorphic inflammatory infiltrates were seen with variably abundant pale staining cytoplasm and focal emperipolesis. There was fibrosis distributed in a lymphangitic pattern with diffuse involvement, and focal necrosis without granuloma formation. Immunohistochemical stains of the histiocytes were positive for CD163 and Factor XIIIa with focal staining of S100 and negative for cytokeratins (AE1/AEE3 and CAM5.2), calretinin, WT-1 and BRAF V600E. As a result, patient was not a candidate for targeted therapy; yet, improved with a course of tapered steroids. Planned for further genetic workup involving the MAPK signaling pathway in the future. DISCUSSION: This case illustrates the significant histological similarities seen in ECD and RDD including lymphangitic distribution, S100-positive histiocytes and emperipolesis. A positive BRAF V600E mutation can be seen in about 50% of ECD cases but not in RDD, giving both diagnostic and therapeutic value. Unfortunately for this patient, the mutation was negative and a definitive subclassification could not be made. However, given the patient’s lack of multisystem involvement including the classic long bone osteosclerosis, a diagnosis of RDD could be favored. CONCLUSIONS: Histiocytic lung disorders vary in clinical manifestations, making it difficult to establish a timely diagnosis. A disparity in identification and targeted treatment still exists, as illustrated in this case. It is prudent to raise awareness of these disorders and highlight the key clinical and histopathologic features which discern them for accurate diagnosis and medical therapy. Reference #1: Haroche J, Abla O; Uncommon histiocytic disorders: Rosai–Dorfman, juvenile xanthogranuloma, and Erdheim–Chester disease. Hematology Am Soc Hematol Educ Program 2015; 2015 (1): 571–578. doi: https://doi.org/10.1182/asheducation.V2015.1.571.3916289 Reference #2: DeMartino E et al. Langerhans Cell Histiocytosis and Other Histiocytic Diseases of the Lung. Clinics in Chest Medicine, Volume 37, Issue 3, 421 - 430 Reference #3: Goyal G, Young JR, Koster MJ, et al. The Mayo Clinic Histiocytosis Working Group Consensus Statement for the Diagnosis and Evaluation of Adult Patients With Histiocytic Neoplasms: Erdheim-Chester Disease, Langerhans Cell Histiocytosis, and Rosai-Dorfman Disease. Mayo Clin Proc. 2019;94(10):2054-2071. doi:10.1016/j.mayocp.2019.02.023 DISCLOSURES: No relevant relationships by Victoria Gonzalez, source=Web Response No relevant relationships by Kristen Hughes, source=Web Response No relevant relationships by Bernadette Schmidt, source=Web Response No relevant relationships by Emad Shehada, source=Web Response

Compound heterozygous protein C variants undetectable by common laboratory testing causing purpura fulminans after the neonatal period.

Compound heterozygous protein C variants undetectable by common laboratory testing causing purpura fulminans after the neonatal period.

Atypical hemolytic and uremic syndrome due to C3 mutation in pancreatic islet transplantation: a case report

BackgroundWe here report on the first observation of a C3 mutation that is related to atypical hemolytic and uremic syndrome (aHUS), which occurred in a pancreatic islet transplant patient. Immunosuppressive treatments, such as calcineurin inhibitors, have been linked to undesirable effects like nephrotoxicity.Case presentationA 40-year-old man with brittle diabetes, who was included in the TRIMECO trial, became insulin-independent 2 months after pancreatic islet transplantation. About 15 months after islet transplantation, the patient exhibited acute kidney injury due to aHUS. Despite plasma exchange and eculizumab treatment, the patient developed end-stage renal disease.A genetic workup identified a missense variant (p.R592Q) in the C3 gene. In vitro, this C3 variant had defective Factor I proteolytic activity with membrane proteins as cofactor proteins, which was thus classified as pathogenic. About 1 year after the aHUS episode, kidney transplantation was carried out under the protection of the specific anti-C5 monoclonal antibody eculizumab. The patient had normal kidney function, with preserved pancreatic islet function 4 years later.ConclusionsPancreatic islet transplantation could have triggered this aHUS episode, but this link needs to be clarified. Although prophylactic eculizumab maintains kidney allograft function, its efficacy still needs to be studied in larger populations.

Demyelinating Charcot-Marie-Tooth neuropathy associated with FBLN5 mutations.

Charcot-Marie-Tooth disease type 1 (CMT1) is a group of autosomal dominantly inherited demyelinating sensorimotor neuropathies. Symptoms usually start in the first to second decade and include distal muscle weakness and wasting, sensory disturbances and foot deformities. The most frequent cause is a duplication of PMP22 whilst point mutations in PMP22 and other genes are rare causes. Recently, FBLN5 mutations have been reported in CMT1 families. Individuals with FBLN5-associated CMT1 were compiled from clinical and research genetic testing laboratories. Clinical data were extracted from medical records or obtained during patients' visits at our centres or primary care sites. Nineteen CMT1 families containing 38 carriers of three different FBLN5 missense variants were identified and a mutational hotspot at c.1117C>T (p.Arg373Cys) was confirmed. Compared to patients with the common PMP22 duplication, individuals with FBLN5 variants had a later age of diagnosis (third to fifth decade) and less severely reduced motor median nerve conduction velocities (around 31m/s). The most frequent clinical presentations were prominent sensory disturbances and painful sensations, often as initial symptom and pronounced in the upper limbs, contrasting with rather mild to moderate motor deficits. Our study confirms the relevance of FBLN5 mutations in CMT1. It is proposed to include FBLN5 in the genetic work-up of individuals suspected with CMT1, particularly when diagnosis is established beyond the first and second decade and comparably moderate motor deficits contrast with early and marked sensory involvement. FBLN5-associated CMT1 has a recognizable clinical phenotype and should be referred to as CMT1H according to the current classification scheme.

Identification of a TMEM127 variant in a patient with paraganglioma and acromegaly.

SummaryThe coincidence of a pheochromocytoma or paraganglioma and a pituitary adenoma in the same patient is a rare condition. In the last few years SDHx and MAX mutations have been identified and discussed as a potential causal connection in cases of coincidence. We describe a case of a middle-aged female patient which presented with acromegaly, a growth hormone-secreting pituitary adenoma and a symptomatic neck paraganglioma. The patient was cured by surgery from both the pituitary tumour and the paraganglioma and is well after ten years follow-up. Due to the unusual coexistence of two neuroendocrine tumours, further molecular genetic testing was performed which revealed a variant in the TMEM127 gene (c245-10C>G).Learning points:Pheochromocytoma/paraganglioma and coexisting functioning pituitary adenoma are a very rare condition. An appropriate treatment of each tumour entity with a multi-disciplinary approach and regular follow-up is needed.The possibility of a hereditary disease should be considered and genetic workup is recommended. Genetic testing should focus primarily on the genes with mutations related to pheochromocytomas and paragangliomas.Next-generation sequencing with multi-gene panel testing is the currently suggested strategy.Genes associated with paragangliomas and pituitary adenomas are SDHA, SDHB, SDHC, SDHD, SDHAF2, MAX and MEN1, while case reports with VHL, RET and NF1 may represent coincidences.Variants of uncertain significance may need ongoing vigilance, in case novel data become available of these variants.