Hemophagocytic lymphohistiocytosis in Egyptian children: diagnosis, treatment challenges, and outcome.

BACKGROUND: Hemophagocyticlymphohistiocytosis (HLH) is a spectrum of immune activation which could be genetically determined, or secondary to an underlying illness. Our aim was to present the clinico-genetic aspects of HLH among Egyptian children and to evaluate the patterns of reactivation and outcome with illustrations of overlap manifestations. RESEARCH DESIGNAND METHODS: We retrospectively collected the data of 55 patients with HLH, registered at Ain Shams University Children's Hospital,Cairo, Egypt. RESULTS: Median age at diagnosis was 19 months (range 2-180), 33 patients (60%) fulfilled the diagnostic HLH criteria at presentation. Fourteen (25.45%) patients had secondary HLH, 15 (27.27%) patients had genetically documented familial HLH (11 had variants in UNC13D gene and one in PRF1 gene), 3 had Griscelli and Chediak-Higashi syndromes. Sixteen patients (29.1%) had reactivations, 8 (50%) of them had molecularly confirmed HLH. We report the death of 40 patients, the median duration from the diagnosis to death of 5 months mostly due to disease activity. CONCLUSIONS: This study confirms that the nonspecific signs and symptoms of HLH are challenging. Genetic testing, though expensive and sophisticated, is integral for the diagnosis. The difficulty in finding non-related donors for stem cell transplantation and the early reactivations are the causes of the inferior outcome.

Transfusion of blood components in pediatric age groups: an evidence-based clinical practice guideline adapted for the use in Egypt using 'Adapted ADAPTE'.

Pediatric transfusion is a complex area of medicine covering a wide age range, from neonates to young adults. Compared to adult practice, there is a relative lack of high-quality research to inform evidence-based guidelines. We aimed to adapt the pre-existing high-quality practice guidelines for the transfusion of blood components in different pediatric age groups to be available for national use by general practitioners, pediatricians, and other health care professionals. The guideline panel included 17 key leaders from different Egyptian institutions. The panel used the Adapted ADAPTE methodology. The panel prioritized the health questions and recommendations according to their importance for clinicians and patients. The procedure included searching for existing guidelines, quality appraisal, and adaptation of the recommendations to the target context of use. The guideline covered all important aspects of the indications, dosing, and administration of packed red cells, platelets, and fresh frozen plasma. It also included transfusion in special situations, e.g., chronic hemolytic anemia and aplastic anemia, management of massive blood loss, malignancies, surgery, recommendations for safe transfusion practices, and recommendations for modifications of cellular blood components. The final version of the adapted clinical practice guideline (CPG) has been made after a thorough review by an external review panel and was guided by their official recommendations and modifications. A set of implementation tools included algorithms, tables, and flow charts to aid decision-making in practice. This adapted guideline serves as a tool for safe transfusion practices in different pediatric age groups.

Communication transforms the impact of the COVID-19 pandemic on children with cancer and their families.

BACKGROUND: The COVID-19 pandemic altered healthcare systems globally, causing delays in care delivery and increased anxiety among patients and families. This study examined how hospital stakeholders and clinicians perceived the global impact of the COVID-19 pandemic on children with cancer and their families. METHODS: This secondary analysis examined data from a qualitative study consisting of 19 focus groups conducted in 8 languages throughout 16 countries. A codebook was developed with novel codes derived inductively from transcript review. In-depth analysis focused on the impact of the COVID-19 pandemic on children with cancer and their families. RESULTS: Eight themes describing the impact of the pandemic on patients and their families were identified and classified into three domains: contributing factors (COVID-19 Policies, Cancer Treatment Modifications, COVID-19 Symptoms, Beliefs), patient-related impacts (Quality of Care, Psychosocial impacts, Treatment Reluctance), and the central transformer (Communication). Participants described the ability of communication to transform the effect of contributing factors on patient-related impacts. The valence of impacts depended on the quality and quantity of communication among clinicians and between clinicians and patients and families. CONCLUSIONS: Communication served as the central factor impacting whether the COVID-19 pandemic positively or negatively affected children with cancer and families. These findings emphasize the key role communication plays in delivering patient-centered care and can guide future development of communication-centered interventions globally.

Constitutional Microsatellite Instability, Genotype, and Phenotype Correlations in Constitutional Mismatch Repair Deficiency.

BACKGROUND & AIMS: Constitutional mismatch repair deficiency (CMMRD) is a rare recessive childhood cancer predisposition syndrome caused by germline mismatch repair variants. Constitutional microsatellite instability (cMSI) is a CMMRD diagnostic hallmark and may associate with cancer risk. We quantified cMSI in a large CMMRD patient cohort to explore genotype-phenotype correlations using novel MSI markers selected for instability in blood. METHODS: Three CMMRD, 1 Lynch syndrome, and 2 control blood samples were genome sequenced to >120× depth. A pilot cohort of 8 CMMRD and 38 control blood samples and a blinded cohort of 56 CMMRD, 8 suspected CMMRD, 40 Lynch syndrome, and 43 control blood samples were amplicon sequenced to 5000× depth. Sample cMSI score was calculated using a published method comparing microsatellite reference allele frequencies with 80 controls. RESULTS: Thirty-two mononucleotide repeats were selected from blood genome and pilot amplicon sequencing data. cMSI scoring using these MSI markers achieved 100% sensitivity (95% CI, 93.6%-100.0%) and specificity (95% CI 97.9%-100.0%), was reproducible, and was superior to an established tumor MSI marker panel. Lower cMSI scores were found in patients with CMMRD with MSH6 deficiency and patients with at least 1 mismatch repair missense variant, and patients with biallelic truncating/copy number variants had higher scores. cMSI score did not correlate with age at first tumor. CONCLUSIONS: We present an inexpensive and scalable cMSI assay that enhances CMMRD detection relative to existing methods. cMSI score is associated with mismatch repair genotype but not phenotype, suggesting it is not a useful predictor of cancer risk.

Effects of COVID-19 on Pediatric Cancer Care: A Multicenter Study of 11 Middle Eastern Countries.

During the COVID-19 pandemic, major challenges are facing pediatric cancer centers regarding access to cancer centers, continuity of the anti-cancer therapy, hospital admission, and infection protection precautions. Pediatric oncologists actively treating children with cancer from 29 cancer centers at 11 countries were asked to answer a survey from May 2020 to August 2020 either directly or through the internet. COVID-19 pandemic affected the access to pediatric cancer care in the form of difficulty in reaching the center in 22 (75.9%) centers and affection of patients' flow in 21 (72.4%) centers. Health care professionals (HCP) were infected with COVID-19 in 20 (69%) surveyed centers. Eighteen centers (62%) modified the treatment guidelines. Care of follow-up patients was provided in-hospital in 8(27.6%) centers, through telemedicine in 10 (34.5%) centers, and just delayed in 11 (38%) centers. Pediatric oncologists had different expectations about the future effects of COVID-19 on pediatric cancer care. Seventy-six percent of pediatric oncologists think the COVID-19 pandemic will increase the use of telemedicine. Fifty-five percent of pediatric oncologists think if the COVID-19 pandemic persists, we will need to change chemotherapy protocols to less myelosuppressive ones. Collaborative studies are required to prioritize pediatric cancer management during COVID-19 era.

Utilizing Multilingual Methods and Rapid Analysis for Global Qualitative Research During a Pandemic.

Historically, qualitative research has complemented quantitative biologic and epidemiologic studies to provide a more complete understanding of pandemics. The COVID-19 pandemic has generated unique and novel challenges for qualitative researchers, who have embraced creative solutions including virtual focus groups and rapid analyses to continue their work. We present our experience conducting a multilingual global qualitative study of healthcare resilience among teams of pediatric oncology professionals during the COVID-19 pandemic. We provide an in-depth description of our methodology and an analysis of factors we believe contributed to our study's success including our use of technology, engagement of a large multilingual team, global partnerships, and framework-based rapid analysis. We hope these techniques may be useful to qualitative researchers conducting studies during the current pandemic, as well as for all pediatric oncology studies including multiple languages or geographically disparate subjects.

Resilient health care in global pediatric oncology during the COVID-19 pandemic.

BACKGROUND: In the face of unprecedented challenges because of coronavirus disease 2019, interdisciplinary pediatric oncology teams have developed strategies to continue providing high-quality cancer care. This study explored factors contributing to health care resilience as perceived by childhood cancer providers in all resource level settings. METHODS: This qualitative study consisted of 19 focus groups conducted in 16 countries in 8 languages. Seven factors have been previously defined as important for resilient health care including: 1) in situ practical experience, 2) system design, 3) exposure to diverse views on the patient's situation, 4) protocols and checklists, 5) teamwork, 6) workarounds, and 7) trade-offs. Rapid turn-around analysis focused on these factors. RESULTS: All factors of health care resilience were relevant to groups representing all resource settings. Focus group participants emphasized the importance of teamwork and a flexible and coordinated approach to care. Participants described collaboration within and among institutions, as well as partnerships with governmental, private, and nonprofit organizations. Hierarchies were advantageous to decision-making and information dissemination. Clinicians were inspired by their patients and explained creative trade-offs and workarounds used to maintain high-quality care. CONCLUSIONS: Factors previously described as contributing to resilient health care manifested differently in each institution but were described in all resource settings. These insights can guide pediatric oncology teams worldwide as they provide cancer care during the next phases of the pandemic. Understanding these elements of resilience will also help providers respond to inevitable future stressors on health care systems.

Treatment outcomes for childhood acute lymphoblastic leukemia in low-middle income country before minimal residual disease risk stratification.

BACKGROUND: Outcome of childhood acute lymphoblastic leukemia (ALL) in low- and middle-income countries is lagging in many aspects including diagnosis, risk stratification, access to treatment and supportive care. OBJECTIVE: to report the outcome of childhood ALL at Ain Shams University Children's Hospitals with the use of risk-based protocols before the implementation of minimal residual disease technology and to evaluate the use of double delayed intensification (DDI) in standard risk patients. METHODS: Two hundred and twenty patients with ALL diagnosed between January 2005 and December 2014 were included in the study. Patients were treated according to a modified CCG 1991 and 1961 for standard and high risk respectively. Patients were stratified into three risk groups: standard risk (SR), high-risk standard arm (HR-SA), and high-risk augmented arm (HR-AA). RESULTS: Among the whole cohort, the 10-year event-free survival (EFS) and overall survival (OS) were 78.1% and 84.3% respectively. Patients with Pre-B immunophenotype (IPT) had significantly better outcome than T-cell IPT (EFS 82.0% versus 58.6%, p < 0.001; OS 86.9% versus 69%, p = 0.003 for Pre-B and T-cell respectively). Among the SR group, patients treated with single delayed intensification (SDI) had comparable EFS and OS rates when compared to patients treated with DDI with EFS 82.4% versus 87.5%, p = 0.825 and OS 88.2% versus 93.5%, p = 0.638 for SDI and DDI groups, respectively. CONCLUSION: The use of risk-based protocol with simple laboratory techniques resulted in acceptable survival outcome in resource limited settings. The use of double delayed intensification showed no survival advantage in patients with standard risk.

Posterior Mediastinal and Cutaneous Back Hemangiomas in Infants: A New Association.

Infantile hemangiomas (IHs) are common vascular tumors. In most cases, a benign course with favorable outcome can be anticipated. IH typically present as cutaneous lesions either with a localized or diffuse segmental distribution. Segmental hemangiomas in the face may be associated with brain and cardiac anomalies (PHACES syndrome), whereas airway involvement has been reported to be associated with hemangiomas in the "beard" area. Multiple cutaneous hemangiomas may be associated with visceral hemangiomas (commonly in the liver). In this report, we present a new association where deep paravertebral hemangiomatous lesions were observed to be associated with cutaneous back hemangiomas in two consecutive cases.

Differential diagnostic features between congenital haemangioma, KHE, and congenital fibrosarcoma: a single-centre experience.

Congenital haemangioma (CH) is a rare benign vascular tumour presenting at birth with excellent prognosis. Usually, CH regresses without treatment within the first few months of life. Kaposiform Haemangioendothelioma (KHE) is another type of vascular tumours that has been described as benign with locally aggressive potential. Although the diagnosis of vascular tumours is usually straightforward based on typical clinical presentation, yet some confusing similarities may exist with congenital sarcomas.Conclusion: Data of cases managed at the vascular anomaly clinic during the period 2015 through 2019 were retrospectively analysed. The study included three groups of patients: cases diagnosed as congenital haemangioma (9 cases), cases of Kaposiform Haemangioendothelioma who presented in the neonatal period (7 cases), as well as cases of congenital fibrosarcoma (4 cases) that were referred to the vascular anomaly clinic because of apparent similarity with vascular tumours. The hallmark of the study was to compare clinical and imaging features in the three groups to facilitate differentiation and remove diagnostic confusion when managing these rare cases in the future. What is Known: • Congenital haemangioma is a rare benign vascular tumour presenting at birth. • Kaposiform Haemangioendothelioma is another type of vascular tumours that has been described as benign with locally aggressive potential. What is New: • Confusing similarities may exist between vascular tumours and congenital sarcomas.

Study of the diagnostic criteria for hemophagocytic lymphohistiocytosis in neonatal and pediatric patients with severe sepsis or septic shock.

Septic shock is a major public health concern. However, the clinical and laboratory criteria for sepsis overlap with those for hemophagocytic lymphohistiocytosis (HLH), and their differentiation can be challenging. The aim of this study was to compare HLH criteria among patients diagnosed with neonatal sepsis and childhood sepsis and to study the outcomes in patients fulfilling the diagnostic criteria for HLH. A cross-sectional study included 50 neonates and children with severe sepsis and/or septic shock. Clinical and laboratory data and HLH diagnostic criteria were studied in relation to patients outcome. Of all patients, 18% fulfilled three of the eight HLH diagnostic criteria, 2% fulfilled four criteria, and 4% fulfilled five criteria. All patients who fulfilled three or more of the criteria died. Mortality was higher in the presence of more positive HLH criteria and in pediatric age groups. However, the distributions of the HLH criteria were comparable for pediatric and neonatal patients with severe sepsis/septic shock, and their mortality rates were not significantly different when based on the criteria.

Patterns, risk factors and outcome predictors of posterior reversible encephalopathy syndrome in pediatric cancer patients.

The purpose of this study was to assess the clinical and radiological patterns and outcome predictors of posterior reversible encephalopathy syndrome (PRES) in pediatric cancer patients. A retrospective study included patients who developed PRES during their treatment at the Children's Cancer Hospital Egypt. A total of 50 patients developed PRES. Leukemia and lymphoma were the commonest diagnoses (64%). Regarding the MRI findings, occipital affection was the most common (92%), followed by frontal and temporal lobes involvement in 32% and 22% respectively and advanced PRES was described in 8 patients. Of the whole patients, 80% had complete clinical resolution and 60% showed complete radiological resolution at 2 weeks' evaluation and 2 patients died out of PRES. Unfavorable outcome was associated with those who had motor dysfunction, status epilepticus at presentation, frontal lobe and thalamic affection and atypical PRES. PRES might present in atypical sites with poor outcome including death.

COVID-19 in Children With Cancer: A Single Low-Middle Income Center Experience.

BACKGROUND: Coronavirus disease-2019 (COVID-19) could be associated with morbidity and mortality in immunocompromised children. OBJECTIVE: The objective of this study was to measure the frequency of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection among hospitalized children with cancer and to detect the associated clinical manifestations and outcomes. METHODOLOGY: A prospective noninterventional study including all hospitalized children with cancer conducted between mid-April and mid-June 2020 in Ain Shams University Hospital, Egypt. Clinical, laboratory, and radiologic data were collected. SARS-CoV-2 infection was diagnosed by reverse transcription polymerase chain reaction tests in nasopharyngeal swabs. RESULTS: Fifteen of 61 hospitalized children with cancer were diagnosed with SARS-CoV-2. Their mean age was 8.3±3.5 years. Initially, 10 (66.7%) were asymptomatic and 5 (33.3%) were symptomatic with fever and/or cough. Baseline laboratory tests other than SARS-CoV-2 reverse transcription polymerase chain reaction were not diagnostic; the mean absolute lymphocyte count was 8.7±2.4×109/L. C-reactive protein was mildly elevated in most of the patients. Imaging was performed in 10 (66.7%) patients with significant radiologic findings detected in 4 (40%) patients. Treatment was mainly supportive with antibiotics as per the febrile neutropenia protocol and local Children Hospital guidance for management of COVID-19 in children. CONCLUSIONS: Pediatric cancer patients with COVID-19 were mainly asymptomatic or with mild symptoms. A high index of suspicion and regular screening with nasopharyngeal swab in asymptomatic hospitalized cancer patients is recommended.

Sirolimus: A Rescue Drug to Control Complications of Extensive Venous Malformation.

Venous malformations represent a major sector of vascular anomalies. Most cases are asymptomatic or subclinical; however, large extensive lesions can cause severe disability and sometimes mortality. In this report, we present a successful case of sirolimus treatment in managing an extensive venous malformation in the pelvis of a 21-month-old boy who presented with life-threatening complications. With a history dating since the day 2 of life, the patient suffered from chronic bleeding due to scrotal skin ulcerations, in addition to recurrent attacks of severe bleeding per rectum necessitating hospital admission and blood transfusion (three attacks since the age of 7 months). Pelvic magnetic resonance image showed the typical findings of extensive venous malformation involving the pelvis, perineum, scrotum, and extending to the gluteal region. The lesion was seen totally encasing the anorectum with marked thickening of their walls almost occluding their lumen. Oral sirolimus (2 mg/m 2 ) was started with a target blood trough level of 5 to 10 ng/mL. Over a follow-up period of 5 months, there was obvious clinical improvement that included healing of skin lesions (scrotal ulcer) with complete re-epithelialization, absence of bleeding per rectum with improvement of constipation, and rise of hemoglobin level from 7.5 to 11.5 g/dL.

Egyptian experience in Langerhans cells histiocytosis: frequent multisystem affection and reactivation rates.

Background: Histiocytoses are unique disorders; their clinical presentations vary from self-healing lesions to life-threatening disseminated disease. Objectives: We aimed to evaluate the different clinical presentations, frequency of reactivations, and treatment outcome of Langerhans cell histiocytosis among Egyptian children. Methods: we restrospectively analyzed the data of 37 Langerhans cell histiocytosis patients (LCH) registered at Ain Shams University Children's Hospital for clinicopathological features, treatment modalities and their outcomes. Results: Twenty seven (73%) of the studied patients with LCH had multisystem disease (MS), 24 (88.9%) of them had risk organ involvement (MS RO+) and only 3 without risk organ (MS RO-). Most of the patients received LCH III protocols. Eleven patients (29.7%) had reactivations with median time till reactivation of 17 months (IQR 5-23).Reactivation rates were 40% and 50% in patients with no evidence of active disease (NAD) and those with active disease better (AD better) at week 6 evaluation respectively (p = 0.71).We report 9 deaths (all had MS RO+, two died after reactivation and 7 had progressive disease. The 5 years EFS and OS were 49.4% and 81.2% respectively. Risk stratification did not significantly affect the EFS or OS (p = 0.64 and p = 0.5 respectively). Conclusion: A high reactivation rate was encountered in children with LCH and MS-RO + irrespective of 6 weeks response to induction therapy. A high mortality in patients with progressive disease necessitates a possible earlier aggressive salvage in such group.

High-sensitivity microsatellite instability assessment for the detection of mismatch repair defects in normal tissue of biallelic germline mismatch repair mutation carriers.

INTRODUCTION: Lynch syndrome (LS) and constitutional mismatch repair deficiency (CMMRD) are hereditary cancer syndromes associated with mismatch repair (MMR) deficiency. Tumours show microsatellite instability (MSI), also reported at low levels in non-neoplastic tissues. Our aim was to evaluate the performance of high-sensitivity MSI (hs-MSI) assessment for the identification of LS and CMMRD in non-neoplastic tissues. MATERIALS AND METHODS: Blood DNA samples from 131 individuals were grouped into three cohorts: baseline (22 controls), training (11 CMMRD, 48 LS and 15 controls) and validation (18 CMMRD and 18 controls). Custom next generation sequencing panel and bioinformatics pipeline were used to detect insertions and deletions in microsatellite markers. An hs-MSI score was calculated representing the percentage of unstable markers. RESULTS: The hs-MSI score was significantly higher in CMMRD blood samples when compared with controls in the training cohort (p<0.001). This finding was confirmed in the validation set, reaching 100% specificity and sensitivity. Higher hs-MSI scores were detected in biallelic MSH2 carriers (n=5) compared with MSH6 carriers (n=15). The hs-MSI analysis did not detect a difference between LS and control blood samples (p=0.564). CONCLUSIONS: The hs-MSI approach is a valuable tool for CMMRD diagnosis, especially in suspected patients harbouring MMR variants of unknown significance or non-detected biallelic germline mutations.

Reticulocyte Hemoglobin Content (Ret He): A Simple Tool for Evaluation of Iron Status in Childhood Cancer.

BACKGROUND: Cancer-related anemia is a common complication of cancer and its treatment that may be mediated by nutritional deficiency or inflammatory cytokines inhibiting erythropoiesis. AIM: We evaluated the value of reticulocyte hemoglobin content (Ret He) as a marker of iron availability for erythropoiesis in childhood cancer and the impact of oral iron supplementation on hematologic parameters in patients with low Ret He. MATERIALS AND METHODS: This prospective study included 100 pediatric patients with cancer on chemotherapy who were screened for the presence of anemia. Patients with anemia underwent testing for complete blood count including Ret He on Sysmex XE 2100 and assessment of reticulocyte count, serum iron, serum ferritin, transferrin saturation, total iron-binding capacity, and C-reactive protein. Patients were classified according to their level of Ret He into normal or low Ret He using a cutoff level of 28 pg. Patients with low Ret He were subjected to 6 weeks' treatment with oral ion and were followed up with complete blood count and iron profile. RESULTS: Thirty-one (77.5%) patients had normal Ret He, and 9 (22.5%) had low Ret He. Ret He was positively correlated with red cell indices, but not with iron parameters. After oral iron supplementation, a significant increase in hemoglobin, reticulocyte count, and iron was found. CONCLUSIONS: We suggest that Ret He could be used as an easy and affordable tool for the assessment of iron deficiency anemia in childhood cancer during chemotherapy treatment. A trial of oral iron in patients with low Ret He may be useful to correct the associated anemia.

A sensitive and scalable microsatellite instability assay to diagnose constitutional mismatch repair deficiency by sequencing of peripheral blood leukocytes.

Constitutional mismatch repair deficiency (CMMRD) is caused by germline pathogenic variants in both alleles of a mismatch repair gene. Patients have an exceptionally high risk of numerous pediatric malignancies and benefit from surveillance and adjusted treatment. The diversity of its manifestation, and ambiguous genotyping results, particularly from PMS2, can complicate diagnosis and preclude timely patient management. Assessment of low-level microsatellite instability in nonneoplastic tissues can detect CMMRD, but current techniques are laborious or of limited sensitivity. Here, we present a simple, scalable CMMRD diagnostic assay. It uses sequencing and molecular barcodes to detect low-frequency microsatellite variants in peripheral blood leukocytes and classifies samples using variant frequencies. We tested 30 samples from 26 genetically-confirmed CMMRD patients, and samples from 94 controls and 40 Lynch syndrome patients. All samples were correctly classified, except one from a CMMRD patient recovering from aplasia. However, additional samples from this same patient tested positive for CMMRD. The assay also confirmed CMMRD in six suspected patients. The assay is suitable for both rapid CMMRD diagnosis within clinical decision windows and scalable screening of at-risk populations. Its deployment will improve patient care, and better define the prevalence and phenotype of this likely underreported cancer syndrome.

No Overt Clinical Immunodeficiency Despite Immune Biological Abnormalities in Patients With Constitutional Mismatch Repair Deficiency.

Immunoglobulin class-switch recombination (CSR) and somatic hypermutations (SHMs) are prerequisites for antibody and immunoglobulin receptor maturation and adaptive immune diversity. The mismatch repair (MMR) machinery, consisting of homologs of MutSα, MutLα, and MutSß (MSH2/MSH6, MLH1/PMS2, and MSH2/MSH3, respectively) and other proteins, is involved in CSR, primarily acting as a backup for nonhomologous end-joining repair of activation-induced cytidine deaminase-induced DNA mismatches and, furthermore, in addition to error-prone polymerases, in the repair of SHM-induced DNA breaks. A varying degree of antibody formation defect, from IgA or selective IgG subclass deficiency to common variable immunodeficiency and hyper-IgM syndrome, has been detected in a small number of patients with constitutional mismatch repair deficiency (CMMRD) due to biallelic loss-of-function mutations in one of the MMR genes (PMS2, MSH6, MLH1, or MSH2). To elucidate the clinical relevance of a presumed primary immunodeficiency (PID) in CMMRD, we systematically collected clinical history and laboratory data of a cohort of 15 consecutive, unrelated patients (10 not previously reported) with homozygous/compound heterozygous mutations in PMS2 (n = 8), MSH6 (n = 5), and MLH1 (n = 2), most of whom manifested with typical malignancies during childhood. Detailed descriptions of their genotypes, phenotypes, and family histories are provided. Importantly, none of the patients showed any clinical warning signs of PID (infections, immune dysregulation, inflammation, failure to thrive, etc.). Furthermore, we could not detect uniform or specific patterns of laboratory abnormalities. The concentration of IgM was increased in 3 out of 12, reduced in 3 out of 12, and normal in 6 out of 12 patients, while concentrations of IgG and IgG subclasses, except IgG4, and of IgA, and specific antibody formation were normal in most. Class-switched B memory cells were reduced in 5 out of 12 patients, and in 9 out of 12 also the CD38hiIgM- plasmablasts were reduced. Furthermore, results of next generation sequencing-based analyses of antigen-selected B-cell receptor rearrangements showed a significantly reduced frequency of SHM and an increased number of rearranged immunoglobulin heavy chain (IGH) transcripts that use IGHG3, IGHG1, and IGHA1 subclasses. T cell subsets and receptor repertoires were unaffected. Together, neither clinical nor routine immunological laboratory parameters were consistently suggestive of PID in these CMMRD patients, but previously shown abnormalities in SHM and rearranged heavy chain transcripts were confirmed.

Thrombopoietin mutation in congenital amegakaryocytic thrombocytopenia treatable with romiplostim.

Congenital amegakaryocytic thrombocytopenia (CAMT) is an inherited disorder characterized at birth by thrombocytopenia with reduced megakaryocytes, which evolves into generalized bone marrow aplasia during childhood. Although CAMT is genetically heterogeneous, mutations of MPL, the gene encoding for the receptor of thrombopoietin (THPO), are the only known disease-causing alterations. We identified a family with three children affected with CAMT caused by a homozygous mutation (p.R119C) of the THPO gene. Functional studies showed that p.R119C affects not only ability of the cytokine to stimulate MPL but also its release, which is consistent with the relatively low serum THPO levels measured in patients. In all the three affected children, treatment with the THPO-mimetic romiplostim induced trilineage hematological responses, remission of bleeding and infections, and transfusion independence, which were maintained after up to 6.5 years of observation. Recognizing patients with THPO mutations among those with juvenile bone marrow failure is essential to provide them with appropriate substitutive therapy and prevent the use of invasive and unnecessary treatments, such as hematopoietic stem cell transplantation or immunosuppression.