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The congenital sideroblastic anemias (CSAs) are a heterogeneous group of inherited disorders of erythropoiesis characterized by pathologic deposits of iron in the mitochondria of developing erythroblasts. Mutations in the mitochondrial glycine carrier SLC25A38 cause the most common recessive form of CSA. Nonetheless, the disease is still rare, there being fewer than 70 reported families. Here we describe the clinical phenotype and genotypes of 31 individuals from 24 families, including 11 novel mutations. We also review the spectrum of reported mutations and genotypes associated with the disease, describe the unique localization of missense mutations in transmembrane domains and account for the reoccurrence of several alleles in different populations.

Background COVID-19 disease has been associated with several cardiovascular complications that rarely occur in the acute phase of the disease. Case report A 13-year-old pediatric patient with congenital sideroblastic anemia associated with YARS2 mutation presenting with COVID-19 infection and worsening pericardial effusion followed by a respiratory failure refractory to supplemental oxygen therapy leading to cardiac arrest. Discussion This case highlights the rapid deterioration that can occur in children with serious hematologic disorders in the context of COVID-19 especially when complicated with pericardial effusion. Conclusion The importance of pericardiocentesis early in order to allow better ventilation in any significant pericardial effusion case associated with COVID-19 infection and the need for prompt care escalation to centers where ECMO is available.

INTRODUCTION: Since the beginning of COVID-19 pandemic, it is known that the severe course of the disease occurs mostly among the elderly, whereas it is rare among children and young adults. Comorbidities, in particular, diabetes and hypertension, clearly associated with age, besides obesity and smoke, are strongly associated with the need for intensive treatment and a dismal outcome. A weaker immunity of the elderly has been proposed as a possible explanation of this uneven age distribution. Thus, there is concern that children treated for cancer may allso be at risk for an unfavourable course of infection. Along the same line, anecdotal information from Wuhan, China, mentioned a severe course of COVID-19 in a child treated for leukaemia. AIM AND METHODS: We made a flash survey on COVID-19 incidence and severity among children on anticancer treatment. Respondents were asked by email to fill in a short Web-based survey. RESULTS: We received reports from 25 countries, where approximately 10,000 patients at risk are followed up. At the time of the survey, more than 200 of these children were tested, nine of whom were positive for COVID-19. Eight of the nine cases had asymptomatic to mild disease, and one was just diagnosed with COVID-19. We also discuss preventive measures that are in place or should be taken and treatment options in immunocompromised children with COVID-19. CONCLUSION: Thus, even children receiving anticancer chemotherapy may have a mild or asymptomatic course of COVID-19. While we should not underestimate the risk of developing a more severe course of COVID-19 than that observed here, the intensity of preventive measures should not cause delays or obstructions in oncological treatment.

Purpose Constitutional mismatch repair deficiency (CMMRD) is a highly penetrant cancer predisposition syndrome caused by biallelic mutations in mismatch repair (MMR) genes. As several cancer syndromes are clinically similar, accurate diagnosis is critical to cancer screening and treatment. As genetic diagnosis is confounded by 15 or more pseudogenes and variants of uncertain significance, a robust diagnostic assay is urgently needed. We sought to determine whether an assay that directly measures MMR activity could accurately diagnose CMMRD. Patients and Methods In vitro MMR activity was quantified using a 3′-nicked G-T mismatched DNA substrate, which requires MSH2-MSH6 and MLH1-PMS2 for repair. We quantified MMR activity from 20 Epstein-Barr virus–transformed lymphoblastoid cell lines from patients with confirmed CMMRD. We also tested 20 lymphoblastoid cell lines from patients who were suspected for CMMRD. We also characterized MMR activity from patients with neurofibromatosis type 1, Li-Fraumeni syndrome, polymerase proofreading-associated cancer syndrome, and Lynch syndrome. Results All CMMRD cell lines had low MMR activity (n = 20; mean, 4.14 ± 1.56%) relative to controls (n = 6; mean, 44.00 ± 8.65%; P < .001). Repair was restored by complementation with the missing protein, which confirmed MMR deficiency. All cases of patients with suspected CMMRD were accurately diagnosed. Individuals with Lynch syndrome (n = 28), neurofibromatosis type 1 (n = 5), Li-Fraumeni syndrome (n = 5), and polymerase proofreading-associated cancer syndrome (n = 3) had MMR activity that was comparable to controls. To accelerate testing, we measured MMR activity directly from fresh lymphocytes, which yielded results in 8 days. Conclusion On the basis of the current data set, the in vitro G-T repair assay was able to diagnose CMMRD with 100% specificity and sensitivity. Rapid diagnosis before surgery in non-neoplastic tissues could speed proper therapeutic management.

YARS2 variants have previously been described in patients with myopathy, lactic acidosis and sideroblastic anemia 2 (MLASA2). YARS2 encodes the mitochondrial tyrosyl-tRNA synthetase, which is responsible for conjugating tyrosine to its cognate mt-tRNA for mitochondrial protein synthesis. Here we describe 14 individuals from 11 families presenting with sideroblastic anemia and YARS2 variants that we identified using a sideroblastic anemia gene panel or exome sequencing. The phenotype of these patients ranged from MLASA to isolated congenital sideroblastic anemia. As in previous cases, inter- and intra-familial phenotypic variability was observed, however, this report includes the first cases with isolated sideroblastic anemia and patients with biallelic YARS2 variants that have no clinically ascertainable phenotype. We identified ten novel YARS2 variants and three previously reported variants. In vitro amino-acylation assays of five novel missense variants showed that three had less effect on the catalytic activity of YARS2 than the most commonly reported variant, p.(Phe52Leu), associated with MLASA2, which may explain the milder phenotypes in patients with these variants. However, the other two missense variants had a more severe effect on YARS2 catalytic efficiency. Several patients carried the common YARS2 c.572 G>T, p.(Gly191Val) variant (minor allele frequency =0.1259) in trans with a rare deleterious YARS2 variant. We have previously shown that the p.(Gly191Val) variant reduces YARS2 catalytic activity. Consequently, we suggest that biallelic YARS2 variants, including severe loss-of-function alleles in trans of the common p.(Gly191Val) variant, should be considered as a cause of isolated congenital sideroblastic anemia, as well as the MLASA syndromic phenotype. This research was funded by grants from Instituto de Salud Carlos III (ISCIII) PI14/01867, PI16/02024 and PI17/00701, TRASCAN (EPICA), CIBERONC (CB16/12/00489; Co-finance with FEDER funds), RTICC (RD12/0036/0068) and Departamento de Salud del Gobierno de Navarra 40/2016. N.M. is supported by a FEHH-Celgene research grant, M.P. was supported by a Sara Borrell fellowship CD12/00540 and RO was supported by Ministerio de Ciencia, Innovación y Universidades of Spain, Subprograma de Formación de Profesorado Universitario (FPU) award number FPU14/04331.

We report on a girl, born to first cousin Lebanese parents, with intellectual disability, seizures, repeated gingivorrhagia, enlarged lower and upper jaws, overgrowth of the gums, high arched and narrow palate, crowded teeth, hirsutism of the back, large abdomen and a small umbilical hernia. Cysts of the mandible, fibrous dysplasia of bones, and enlarged adenoids causing around 60% narrowing of the nasopharyngeal airways were noted at radiographic examination. Her brother presented with the same features in addition to a short stature, an ostium secundum, and more pronounced intellectual disability. He died at the age of 8 years from a severe pulmonary infection and repeated bleeding episodes. A clinical diagnosis of Ramon syndrome was made. Whole exome sequencing studies performed on the family revealed the presence of a novel homozygous missense mutation in ELMO2 gene, p.I606S in the affected individuals. Loss of function mutations in ELMO2 have been recently described in another clinically distinct condition: primary intraosseous vascular malformation or intraosseous hemangioma, called VMOS. Review of the literature and differential diagnoses are discussed.

BACKGROUND Constitutional mismatch repair deficiency syndrome (CMMRD) is a severe cancer predisposition syndrome resulting in early onset central nervous system (CNS) and other cancers. International guidelines for surveillance exist but no study has systematically evaluated the efficacy of this protocol. METHODS We surveyed all confirmed CMMRD patients in the International Replication Repair Deficiency Consortium. A surveillance protocol consisting of frequent biochemical, endoscopic and imaging (CNS and total body MRI) studies were employed. Survival analyses and efficacy of each method were assessed. RESULTS Surveillance data were collected from 105 CMMRD individuals from 41 countries. Of the 193 malignant tumors, CNS malignancies were the most common (44%). The surveillance protocol uncovered 49 asymptomatic tumors including 16 glioblastomas and medulloblastomas. Five-year overall survival was 89% for tumors discovered by surveillance, and 61% for symptomatic tumors (p6 months as per protocol. Finally, of the low grade tumors identified asymptomatically, 5 were low grade gliomas. All of the low grade gliomas, which were not resected transformed to high grade tumors at a median of 1.6 ± 0.9 years. CONCLUSION These data support a survival benefit in CMMRD patients undergoing a surveillance protocol. Adherence to protocol and resection of lower grade lesions may improve survival for patients with CNS tumors.

Retinoblastoma is an ocular tumor that occurs in young children, in either heritable or sporadic manner. The relative rarity of retinoblastoma, and the need for expensive equipment, anesthesia, and pediatric ophthalmologic expertise, are barriers for effective treatment in developing countries. Also, with an average age-adjusted incidence of two to five cases per million children, patient number limits development of local expertise in countries with small populations. Lebanon is a small country with a population of approximately 4.5 million. In 2012, a comprehensive retinoblastoma program was formalized at the Children's Cancer Institute (CCI) at the American University of Beirut Medical Center, and resources were allocated for efficient interdisciplinary coordination to attract patients from neighboring countries such as Syria and Iraq, where such specialized therapy is also lacking. Through this program, care was coordinated across hospitals and borders such that patients would receive scheduled chemotherapy at their institution, and monthly retinal examinations and focal laser therapy at the CCI in Lebanon. Our results show the feasibility of successful collaboration across borders, with excellent patient and physician adherence to treatment plans. This was accompanied by an increase in patient referrals, which enables continued expertise development. However, the majority of patients presented with advanced intraocular disease, necessitating enucleation in 90% of eyes in unilateral cases, and more than 50% of eyes in bilateral cases. Future efforts need to focus on expanding the program that reaches to additional hospitals in both countries, and promoting early diagnosis, for further improvement of globe salvage rates.

Diamond-Blackfan Anemia (DBA) is a rare inherited form of pure red cell aplasia that usually manifests in infancy or early childhood, and is characterized by normochromic macrocytic anemia and bone marrow erythroblastopenia. The majority of DBA cases are associated with mutations in ribosomal protein genes. Here, we describe a Lebanese girl with RPL5-mutated DBA unresponsive to steroid treatment who died from complications following late hematopoietic stem cell transplantation performed at the age of 15 years.

Constitutional Mismatch Repair Deficiency (CMMRD) is a rare cancer predisposition syndrome, presenting in childhood, in which affected patients develop various malignancies such as hematological, gastrointestinal and central nervous system tumors. Although guidelines are being increasingly developed for surveillance and early detection of cancers in affected families, there are no clear recommendations regarding choice of therapy and very scarce information about tolerance to chemotherapy and radiation in these patients. We report the pedigree of a consanguineous family with four affected children. Although clinical and molecular tests confirm CMMRD, genetic testing revealed heterogeneous mutations. The index case developed severe toxicity from therapy for glioblastoma and T-cell leukemia and died from an infection while in complete remission. His sister developed a malignant brain tumor while undergoing surveillance for a low grade brain lesion and is still undergoing follow-up. This family illustrates the difficulties and opportunities with challenging diagnosis, surveillance and choice of therapy for children with CMMRD and the need for increased awareness and more information about this rare but important syndrome.

Purpose Recurrent glioblastoma multiforme (GBM) is incurable with current therapies. Biallelic mismatch repair deficiency (bMMRD) is a highly penetrant childhood cancer syndrome often resulting in GBM characterized by a high mutational burden. Evidence suggests that high mutation and neoantigen loads are associated with response to immune checkpoint inhibition. Patients and Methods We performed exome sequencing and neoantigen prediction on 37 bMMRD cancers and compared them with childhood and adult brain neoplasms. Neoantigen prediction bMMRD GBM was compared with responsive adult cancers from multiple tissues. Two siblings with recurrent multifocal bMMRD GBM were treated with the immune checkpoint inhibitor nivolumab. Results All malignant tumors (n = 32) were hypermutant. Although bMMRD brain tumors had the highest mutational load because of secondary polymerase mutations (mean, 17,740 ± standard deviation, 7,703), all other high-grade tumors were hypermutant (mean, 1,589 ± standard deviation, 1,043), similar to other cancers that responded favorably to immune checkpoint inhibitors. bMMRD GBM had a significantly higher mutational load than sporadic pediatric and adult gliomas and all other brain tumors (P < .001). bMMRD GBM harbored mean neoantigen loads seven to 16 times higher than those in immunoresponsive melanomas, lung cancers, or microsatellite-unstable GI cancers (P < .001). On the basis of these preclinical data, we treated two bMMRD siblings with recurrent multifocal GBM with the anti–programmed death-1 inhibitor nivolumab, which resulted in clinically significant responses and a profound radiologic response. Conclusion This report of initial and durable responses of recurrent GBM to immune checkpoint inhibition may have implications for GBM in general and other hypermutant cancers arising from primary (genetic predisposition) or secondary MMRD.

Background Children with malignant bone tumors have average 5-year survival rates of 60% to 70% with current multimodality therapy. Local control modalities aimed at preserving function greatly influence the quality of life of long-term survivors. In developing countries, the limited availability of multidisciplinary care and limited expertise in specialized surgery and pediatric radiation therapy, as well as financial cost, all form barriers to achieving optimal outcomes in this population. Methods We describe the establishment of a collaborative pediatric bone tumor program among a group of pediatric oncologists in Lebanon and Syria. This program provides access to specialized local control at a tertiary children’s cancer center to pediatric patients with newly diagnosed bone tumors at participating sites. Central review of pathology, staging, and treatment planning is performed in a multidisciplinary tumor board setting. Patients receive chemotherapy at their respective centers on a unified treatment plan. Surgery and/or radiation therapy are performed centrally by specialized staff at the children’s cancer center. Cost barriers were resolved through a program development initiative led by St Jude Children’s Research Hospital. Once program feasibility was achieved, the Children’s Cancer Center of Lebanon Foundation, via fundraising efforts, provided continuation of program-directed funding. Results Findings over a 3-year period showed the feasibility of this project, with timely local control and protocol adherence at eight collaborating centers. We report success in providing standard-of-care multidisciplinary therapy to this patient population with complex needs and financially challenging surgical procedures. Conclusion This initiative can serve as a model, noting that facilitating access to specialized multidisciplinary care, resolution of financial barriers, and close administrative coordination all greatly contributed to the success of the program.

BACKGROUND Mutations in mismatch repair (MMR) and DNA-polymerase (POL) genes lead to DNA replication repair deficiency (RRD), resulting in a growing group of previously under-recognized childhood brain tumors. Medulloblastoma and embryonal tumors are rarely reported in RRD. Their biological and clinical significance is unknown. METHODS We analyzed the clinical and genomic data of embryonal tumors registered in the International RRD Consortium. RESULTS Twenty-six tumors were centrally reviewed to confirm medulloblastoma (n=18), embryonal-tumor, NOS (n=5), and three glioblastoma (excluded). Embryonal tumors were observed at a young age (median: 7-years, IQR: 5;11), and all but one exhibited clinical cues (café-au-lait macules/ family history) of germline RRD. Medulloblastomas with RRD exhibited high-risk features, including anaplastic histology (50%), and SHH-subgroup with TP53-mutation (50%). Importantly, 68% harbored POLE/POLD1 mutations, resulting in median tumor mutation burden of 164 mut/mb. POL-mutated tumors were significantly ultra-hypermutated (>100 mut/mb) than tumors with MMR-deficiency alone (p=0.015). Synchronous and metachronous tumors were observed in 40%. However 90% of the deaths were related to the diagnosis of embryonal CNS tumor. Median survival for the entire cohort was 17-months (95% CI: 10 to 23). Predicted 3-year survival was 37% for medulloblastoma, with no survivors among other embryonal tumors. CONCLUSIONS This is the largest cohort of replication repair deficient medulloblastoma reported till date. The tumors are hypermutated, harbor somatic mutations in TP53 and/or POLE/POLD1, and have very poor survival with current chemo-irradiation based approaches. These biologically unique tumors expand the spectrum of high-risk TP53-mutant SHH-medulloblastoma, and need novel strategies for treatment.

BACKGROUND: Thrombocytopenia is a serious issue for all patients with classical Wiskott-Aldrich syndrome (WAS) and X-linked thrombocytopenia (XLT) because it causes severe and life-threatening bleeding. Lentiviral gene therapy (GT) for WAS has shown promising results in terms of immune reconstitution. However, despite the reduced severity and frequency of bleeding events, platelet counts remain low in GT-treated patients. OBJECTIVE: We carefully investigated platelet defects in terms of phenotype and function in untreated patients with WAS and assessed the effect of GT treatment on platelet dysfunction. METHODS: We analyzed a cohort of 20 patients with WAS/XLT, 15 of them receiving GT. Platelet phenotype and function were analyzed by using electron microscopy, flow cytometry, and an aggregation assay. Platelet protein composition was assessed before and after GT by means of proteomic profile analysis. RESULTS: We show that platelets from untreated patients with WAS have reduced size, abnormal ultrastructure, and a hyperactivated phenotype at steady state, whereas activation and aggregation responses to agonists are decreased. GT restores platelet size and function early after treatment and reduces the hyperactivated phenotype proportionally to WAS protein expression and length of follow-up. CONCLUSIONS: Our study highlights the coexistence of morphologic and multiple functional defects in platelets lacking WAS protein and demonstrates that GT normalizes the platelet proteomic profile with consequent restoration of platelet ultrastructure and phenotype, which might explain the observed reduction of bleeding episodes after GT. These results are instrumental also from the perspective of a future clinical trial in patients with XLT only presenting with microthrombocytopenia.

Hereditary biallelic mismatch repair deficiency (BMMRD) is caused by biallelic mutations in the mismatch repair (MMR) genes and manifests features of neurofibromatosis type 1, gastrointestinal (GI) polyposis, and GI, brain, and hematological cancers. This is the first study to characterize the GI phenotype in BMMRD using both retrospective and prospective surveillance data.The International BMMRD Consortium was created to collect information on BMMRD families referred from around the world. All patients had germline biallelic MMR mutations or lack of MMR protein staining in normal and tumor tissue. GI screening data were obtained through medical records with annual updates.Thirty-five individuals from seven countries were identified with BMMRD. GI data were available on 24 of 33 individuals (73%) of screening age, totaling 53 person-years. The youngest age of colonic adenomas was 7, and small bowel adenoma was 11. Eight patients had 19 colorectal adenocarcinomas (CRC; median age 16.7 years, range 8-25), and 11 of 18 (61%) CRC were distal to the splenic flexure. Eleven patients had 15 colorectal surgeries (median 14 years, range 9-25). Four patients had five small bowel adenocarcinomas (SBC; median 18 years, range 11-33). Two CRC and two SBC were detected during surveillance within 6-11 months and 9-16 months, respectively, of last consecutive endoscopy. No patient undergoing surveillance died of a GI malignancy. Familial clustering of GI cancer was observed.The prevalence and penetrance of GI neoplasia in children with BMMRD is high, with rapid development of carcinoma. Colorectal and small bowel surveillance should commence at ages 3-5 and 8 years, respectively.

Constitutional mismatch repair deficiency (CMMRD) is a devastating cancer predisposition syndrome for which data regarding clinical manifestations, molecular screening tools and management are limited.We established an international CMMRD consortium and collected comprehensive clinical and genetic data. Molecular diagnosis of tumour and germline biospecimens was performed. A surveillance protocol was developed and implemented.Overall, 22/23 (96%) of children with CMMRD developed 40 different tumours. While childhood CMMRD related tumours were observed in all families, Lynch related tumours in adults were observed in only 2/14 families (p=0.0007). All children with CMMRD had café-au-lait spots and 11/14 came from consanguineous families. Brain tumours were the most common cancers reported (48%) followed by gastrointestinal (32%) and haematological malignancies (15%). Importantly, 12 (30%) of these were low grade and resectable cancers. Tumour immunohistochemistry was 100% sensitive and specific in diagnosing mismatch repair (MMR) deficiency of the corresponding gene while microsatellite instability was neither sensitive nor specific as a diagnostic tool (p0.0001). Furthermore, screening of normal tissue by immunohistochemistry correlated with genetic confirmation of CMMRD. The surveillance protocol detected 39 lesions which included asymptomatic malignant gliomas and gastrointestinal carcinomas. All tumours were amenable to complete resection and all patients undergoing surveillance are alive.CMMRD is a highly penetrant syndrome where family history of cancer may not be contributory. Screening tumours and normal tissues using immunohistochemistry for abnormal expression of MMR gene products may help in diagnosis and early implementation of surveillance for these children.

A recent Intercontinental Cooperative ITP Study Group (ICIS) meeting in September 2015 focused on immunomodulation across the spectrum of autoimmune conditions. It became clear to the attendees that in this wide range of conditions, there is a subset of patients that remain highly refractory to first line therapy. Therapeutic approaches to these patients vary greatly and while many different immunomodulatory agents have been investigated, few have seen universal success. We outline here the landscape of immunomodulation therapy for refractory patients across a variety of autoimmune conditions in order to highlight the variety of agents that have been studied, the lack of overall consensus about management, and the need for ongoing research in this area.

We report the case of a 6-year-old boy diagnosed with acute promyelocytic leukemia (AML-M3V) when he presented with pallor, abdominal pain, anorexia, and fatigue. Induction chemotherapy was started according to the AML-BFM 98 protocol along with Vesanoid (ATRA, All-trans retinoic acid). On the sixth day of induction, he developed splenic and gallbladder infarcts. Splenectomy and cholecystectomy were performed while chemotherapy induction continued as scheduled. Four days later, he developed ischemic areas in the kidneys and ischemic colitis in the sigmoid colon. Hypercoagulation studies showed severe deficiency of protein C. Tests showed protein C 16% (reference range 70-140%), protein S 87% (reference range 70-140%), antithrombin III 122% (reference range 80-120%), prothrombin time 13.6 s (reference = 11.3), INR (international normalized ratio) 1.21, partial thromboplastin time 33 s (reference = 33), fibrinogen 214 mg/dl, D-dimer 970 μg/ml, factor II 98%, and that antinuclear antibody, antiphospholipid antibodies, mutation for factor II gene (G20210A), and mutation for Arg506 Gln of factor V were all negative (factor V Leiden). There was no evidence of clinical disseminated intravascular coagulation (DIC). He was treated with low molecular weight heparin and did well. He continues to be in complete remission 7 years later with normal protein C levels. Acquired protein C deficiency can occur in a variety of settings and has been reported in acute myelocytic leukemia. However, clinically significant thrombosis in the absence of clinical DIC, such as our case, remains extremely rare.

PURPOSE: To describe the 5-year experience of a multidisciplinary limb salvage program for children and adolescents with malignant bone tumors in Lebanon. PATIENTS AND METHODS: Between January 2002 to February 2007, 30 children and adolescents (2 with Ewing sarcoma and 28 with osteosarcoma) underwent Limb Salvage Surgeries (LSS) at the American University of Beirut Medical Center after partnering with the multidisciplinary team at St. Judes Children's Research Hospital (SJCRH). Procedures performed included 12 Repiphysis, noninvasively expandable, prostheses inserted in skeletally immature children, 15 modular prostheses, 2 allografts and 1 rotationplasty. All patients received pre- and postoperative chemotherapy. RESULTS: With a mean follow-up of 31 months, 20 patients are now off therapy, 4 died, and 6 are receiving chemotherapy (3 due to pulmonary recurrence). Complications of surgery included infections in three cases, failure of the expansion mechanism in two, femoral stem fracture in one, prostheses femoral stem loosening in one and wound dehiscence in one. Lengthening of Repiphysis prostheses was achieved by subjecting the limb to an electromagnetic field that would allow controlled release of the Repiphysis expansion mechanism. Ten patients underwent a total of 42 lengthening procedures with an average of 9 mm lengthened per procedure (range 2-15 mm). All patients have good function of the affected limb. CONCLUSION: Our LSS results are comparable to those reported in the literature. Collaboration with SJCRH and fund raising were critical to the program's success. This endeavor could serve as a model for establishing LSS programs in developing countries.

We present an extensive assessment of mutation burden through sequencing analysis of >81,000 tumors from pediatric and adult patients, including tumors with hypermutation caused by chemotherapy, carcinogens, or germline alterations. Hypermutation was detected in tumor types not previously associated with high mutation burden. Replication repair deficiency was a major contributing factor. We uncovered new driver mutations in the replication-repair-associated DNA polymerases and a distinct impact of microsatellite instability and replication repair deficiency on the scale of mutation load. Unbiased clustering, based on mutational context, revealed clinically relevant subgroups regardless of the tumors' tissue of origin, highlighting similarities in evolutionary dynamics leading to hypermutation. Mutagens, such as UV light, were implicated in unexpected cancers, including sarcomas and lung tumors. The order of mutational signatures identified previous treatment and germline replication repair deficiency, which improved management ofpatients and families. These data will inform tumor classification, genetic testing, and clinical trial design.

Summary Introduction Glomus tumor is a well known pathology in hand surgery; in addition to sites in the upper limbs, it can also affect the lower limbs and develop in other parts of the body. Materials and methods Seven females and four maies with glomus tumors underwent surgery between 1990 and 1998 at our hospital. These cases were retrospectively studied, and immunohistochemical staining was carried out for vimentin, factor VIII and CD34. Results At the time of diagnosis, the mean age of the patients was 49 years, with a mean follow-up of 18.5 months. Regarding tumor site, there were six digital, one wrist, two neck and two lower limblocations. In this series, familial incidence was observed in two cases, i.e., two sisters with tumor occurrence at the same digital site. Tumor size varied from 0.2 to 5 cm. In agreement with the findings in the literature, the present results showed only a low incidence of locations other than in the upper and lower limbs. Moerover, no multiple locations or degenerative malignancy were observed, both of which are known to be rare. In ail cases, the histological aspect of these tumors was typically benign. Immunohistochemical studies of the tumor cells were positive for anti-vimentin antibody in all cases, negative for anti-factor VIII in ail cases and irregularly positive for anti-CD34 antibody. Discussion It was not possible to confirm the specificity of the anti-CD34 antibody for glomus tumor in this series. The hypothesis of the endothelial origin of glomus tumor can probably be dis missed in the absence of the expression of anti-factor VIII and anti-CD34 antibodies.

Neuroblastoma (NB) is a rare pediatric disease in Lebanon for which poor prognosis remains a major challenge. Genetic polymorphism of genes coding for drug‑metabolizing enzymes may influence the response of a patient to chemotherapy. This study investigates a possible association between CYP3A4/5 polymorphism and expression levels and survival in NB patients. All patients with stage III and IV NB diagnosed between 1993 and 2012 in three major hospitals in Beirut were included (n=27). Demographic information and survival time were obtained from medical records. CYP3A4 and CYP3A5 genotypes and expression levels were determined in archival tumors by polymerase chain reaction (PCR) and restriction fragment length polymorphism and quantitative PCR, respectively. Additionally, MYCN amplification was assessed. A Cox proportional hazards model was used to evaluate potential associations, adjusting for MYCN amplification. A statistically significant increase in the risk of mortality was observed in patients with MYCN amplification [hazard ratio (HR) 4.11, 95% confidence interval (CI) 1.14‑14.80]. Patients with CYP3A5 expression levels above the median had a lower risk of mortality (HR 0.61, 95% CI 0.21‑1.74) and patients with CYP3A4 expression levels above the median had a higher risk of mortality (HR 2.00, 95% CI 0.67‑5.90). CYP3A5*3/*3 homozygote mutants had a 4.3‑fold increase in the risk of mortality compared with that of homozygote wild‑type or heterozygote mutants (HR 4.30, 95% CI 0.56‑33.30). Carriers of the CYP3A4*1B mutant allele had a 52% lower risk of mortality compared with that of non‑carriers (HR 0.48, 95% CI 0.06‑3.76). Although the results of the present study did not achieve statistical significance, associations were observed, which indicates that CYP3A4 and CYP3A5 may modulate the clinical outcome of NB. Further studies with larger sample sizes are required to characterize the effects of the polymorphism and expression levels of CYP3A4/5 on the survival of patients with NB.

Familial hemophagocytic lymphohistiocytosis (FHL) is typically an early onset, fatal disease characterized by a sepsislike illness with cytopenia, hepatosplenomegaly, and deficient lymphocyte cytotoxicity. Disease-causing mutations have been identified in genes encoding perforin (PRF1/FHL2), Munc13-4 (UNC13D/FHL3), and syntaxin-11 (STX11/FHL4). In contrast to mutations leading to loss of perforin and Munc13-4 function, it is unclear how syntaxin-11 loss-of-function mutations contribute to disease. We show here that freshly isolated, resting natural killer (NK) cells and CD8+ T cells express syntaxin-11. In infants, NK cells are the predominant perforin-containing cell type. NK cells from FHL4 patients fail to degranulate when encountering susceptible target cells. Unexpectedly, IL-2 stimulation partially restores degranulation and cytotoxicity by NK cells, which could explain the less severe disease progression observed in FHL4 patients, compared with FHL2 and FHL3 patients. Since the effector T-cell compartment is still immature in infants, our data suggest that the observed defect in NK-cell degranulation may contribute to the pathophysiology of FHL, that evaluation of NK-cell degranulation in suspected FHL patients may facilitate diagnosis, and that these new insights may offer novel therapeutic possibilities.

e21020 Background: Osteosarcoma and Ewing sarcoma are the most common malignant bone tumors in pediatrics. Average 5-year survival rates of 60-70% are achieved with current multimodality therapy. L...

Purpose: Constitutional mismatch repair deficiency (CMMRD) is a devastating cancer predisposition syndrome affecting children born with two mutated alleles in one of four mismatch repair genes. Data regarding clinical manifestations, molecular screening tools and management are limited. Patients and methods: We established an international CMMRD consortium and collected comprehensive clinical and genetic data. Molecular diagnosis of tumor and germline biospecimens were performed. A surveillance protocol was developed and implemented. Results: Overall, 27/30 (90%) of children with CMMR-D developed 48 different tumors. While childhood CMMR-D related tumors were observed in all families, Lynch related tumors in adults were observed in only 2/17 families (p We detected 17 different germline MMR mutations. These included mutations in PMS2(8), MSH6(7) and MLH1(2). Importantly 7/17 mutations were previously unreported. Brain tumors were the most common cancers reported (44%) followed by gastrointestinal (33%) and hematological malignancies (17%). Importantly, 14 (29%) of these were low grade and respectable cancers. Tumor immunohistochemistry was 100% sensitive and specific in diagnosing MMR deficiency of the corresponding gene while microsatellite instability was neither sensitive nor specific as a diagnostic tool (p Conclusion: CMMR-D is a highly penetrant syndrome where family history of cancer may not be contributory. Screening tumors and normal tissues using immunohistochemistry for abnormal expression of MMR gene products helps in diagnosis and early implementation of surveillance for these children. Citation Format: Doua Bakry, Brittany Campbell, Carol Durno, Melyssa Aronson, Qasim Alharbi, Musa Alharbi, Shlomi Constantini, Aaron Pollett, Shay Ben-Shachar, Jordan Lerner-Ellis, Steven Gallinger, Ronit Elhasid, Roula Farah, Ibrahim Qaddoumi, Matthew Mistry, Ramyar Lily, Steve Keiles, Rina Dvir, Derek Stephens, David Malkin, Eric Bouffet, Cynthia Hawkins, Uri Tabori. Novel genetic and clinical determinants of Constitutional Mismatch Repair Deficiency syndrome: Report from the CMMRD consortium. [abstract]. In: Proceedings of the AACR Special Conference: Cancer Susceptibility and Cancer Susceptibility Syndromes; Jan 29-Feb 1, 2014; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(23 Suppl):Abstract nr 35. doi:10.1158/1538-7445.CANSUSC14-35