Draft consensus guidelines for diagnosis and treatment of Shwachman-Diamond syndrome

Heterozygous missense variant in EIF6 gene: A novel form of Shwachman-Diamond syndrome?

Shwachman-Diamond syndrome (SDS) is a rare multisystem ribosomal biogenesis disorder characterized by exocrine pancreatic insufficiency, hematologic abnormalities and bony abnormalities. About 90% of patients have biallelic mutations in SBDS gene. Three additional genes-EFL1, DNAJC21 and SRP54 have been reported in association with a SDS phenotype. However, the cause remains unknown for ~10% of patients. Herein, we report a 6-year-old Chinese boy, who presented in the neonatal period with pancytopenia, liver transaminitis with hepatosplenomegaly and developmental delay, and subsequently developed pancreatic insufficiency complicated by malabsorption and poor growth. Exome sequencing identified a novel de novo heterozygous variant in EIF6 (c.182G>T, p.Arg61Leu). EIF6 protein inhibits ribosomal maturation and is removed in the late steps of ribosomal maturation by SBDS and EFL1 protein. Given the interaction of EIF6 with SBDS and EFL1, we postulate heterozygous variants in EIF6 as a novel cause of Shwachman-Diamond-like phenotype. We compared the phenotype of our patient with those in patients with mutation in SBDS, EFL1, DNAJC21, and SRP54 genes to support this association. Identification of more cases of this novel phenotype would strengthen the association with the genetic etiology.

Nonsense Suppression Therapy: New Hypothesis for the Treatment of Inherited Bone Marrow Failure Syndromes

Inherited bone marrow failure syndromes (IBMFS) are a group of cancer-prone genetic diseases characterized by hypocellular bone marrow with impairment in one or more hematopoietic lineages. The pathogenesis of IBMFS involves mutations in several genes which encode for proteins involved in DNA repair, telomere biology and ribosome biogenesis. The classical IBMFS include Shwachman–Diamond syndrome (SDS), Diamond–Blackfan anemia (DBA), Fanconi anemia (FA), dyskeratosis congenita (DC), and severe congenital neutropenia (SCN). IBMFS are associated with high risk of myelodysplastic syndrome (MDS), acute myeloid leukemia (AML), and solid tumors. Unfortunately, no specific pharmacological therapies have been highly effective for IBMFS. Hematopoietic stem cell transplantation provides a cure for aplastic or myeloid neoplastic complications. However, it does not affect the risk of solid tumors. Since approximately 28% of FA, 24% of SCN, 21% of DBA, 20% of SDS, and 17% of DC patients harbor nonsense mutations in the respective IBMFS-related genes, we discuss the use of the nonsense suppression therapy in these diseases. We recently described the beneficial effect of ataluren, a nonsense suppressor drug, in SDS bone marrow hematopoietic cells ex vivo. A similar approach could be therefore designed for treating other IBMFS. In this review we explain in detail the new generation of nonsense suppressor molecules and their mechanistic roles. Furthermore, we will discuss strengths and limitations of these molecules which are emerging from preclinical and clinical studies. Finally we discuss the state-of-the-art of preclinical and clinical therapeutic studies carried out for IBMFS.

Congenital Diarrheal Diseases

Early diagnosis of diarrhea is critical to prevent disease progression. Diarrhea in newborns can be congenital or acquired; acquired diarrheas are the major cause in infants. Congenital diarrheal diseases are rare and include defects in digestion, absorption, and transport of nutrients, and electrolytes; disorders of enterocyte differentiation and polarization; defects of enteroendocrine cell differentiation; dysregulation of the intestinal immune response; and dysfunction of the immune system. This review discusses the clinical approach that may help in early identification and management of different congenital diarrheal diseases.

Hematopoietic Stem Cell Transplantation for Shwachman-Diamond Syndrome

We report the outcomes of hematopoietic stem cell transplantation (HSCT) for 52 patients with Shwachman-Diamond syndrome (SDS) who underwent transplantation between 2000 and 2017. The median age at transplantation was 11 years, and the median duration of follow-up was 60 months. The indication for HSCT was bone marrow failure (BMF; cytopenia or aplastic anemia) in 39 patients and myelodysplasia (MDS)/acute myelogenous leukemia (AML) in 13 patients. The donor type was an HLA-matched sibling for 18 patients, an HLA-matched or mismatched relative for 6 patients, and an HLA-matched or mismatched unrelated donor for 28 patients. Preparative regimens for BMF were myeloablative in 13 patients and reduced intensity in 26. At the time of this report, 29 of the 39 patients with BMF were alive, and the 5-year overall survival was 72% (95% confidence interval, 57% to 86%). Graft failure and graft-versus-host disease were the predominant causes of death. Preparative regimens for patients with MDS/AML were myeloablative in 8 and reduced intensity in 5. At the time of this report, only 2 of 13 patients were alive (15%), with relapse the predominant cause of death. Survival after transplantation for SDS-related BMF is better compared with historical reports, but strategies are needed to overcome graft failure and graft-versus-host disease. For SDS- related MDS or AML, transplantation does not extend survival. Rigorous surveillance and novel treatments for leukemia are urgently needed.

Reduction of Extramedullary Complications in Patients With Acute Myeloid Leukemia/Myelodysplastic Syndrome Treated With Azacitidine

The distinction between myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML) often relies on an arbitrary marrow blast cutoff of 30% in pediatrics and 20% in adults. There is little data about the treatment of children with extramedullary myeloid malignancy that has features of both, MDS and AML. Herein, we report for the first time 2 patients MDS/AML (1 with Shwachman-Diamond syndrome and 1 with idiopathic MDS and monosomy 7) who presented with extramedullary complications, received treatment with azacitidine, achieved complete remission and subsequently underwent hematopoietic stem cell transplantation.

A Prospective Study of Hematologic Complications and Long-Term Survival of Italian Patients Affected by Shwachman-Diamond Syndrome

OBJECTIVE

To describe the hematologic outcome and long-term survival of patients enrolled in the Shwachman-Diamond syndrome Italian Registry.

STUDY DESIGN

A retrospective and prospective study of patients recorded in the Shwachman-Diamond syndrome Italian Registry.

RESULTS

The study population included 121 patients, 69 males and 52 females, diagnosed between 1999 and 2018. All patients had the clinical diagnosis confirmed by mutational analysis on the SBDS gene. During the study period, the incidence of SDS was 1 in 153 000 births. The median age of patients with SDS at diagnosis was 1.3 years (range, 0-35.6 years). At the first hematologic assessment, severe neutropenia was present in 25.8%, thrombocytopenia in 25.5%, and anemia in 4.6% of patients. A normal karyotype was found in 40 of 79 patients, assessed whereas the most frequent cytogenetic abnormalities were isochromosome 7 and interstitial deletion of the long arm of chromosome 20. The cumulative incidence of severe neutropenia, thrombocytopenia, and anemia at 30 years of age were 59.9%, 66.8%, and 20.2%, respectively. The 20-year cumulative incidence of myelodysplastic syndrome/leukemia and of bone marrow failure/severe cytopenia was 9.8% and 9.9%, respectively. Fifteen of 121 patients (12.4%) underwent allogeneic stem cell transplantation. Fifteen patients (12.4%) died; the probability of overall survival at 10 and 20 years was 95.7% and 87.4%, respectively.

CONCLUSIONS

Despite an improvement in survival, hematologic complications still cause death in patients with SDS. Further studies are needed to optimize type and modality of hematopoietic stem cell transplantation and to assess the long-term outcome in nontransplanted patients.

Long-term outcome after allogeneic hematopoietic stem cell transplantation for Shwachman-Diamond syndrome: a retrospective analysis and a review of the literature by the Severe Aplastic Anemia Working Party of the European Society for Blood and Marrow Transplantation (SAAWP-EBMT)

Allogeneic hematopoietic stem cell transplantation (HSCT) is a curative procedure in patients with Shwachman-Diamond syndrome (SDS) with bone marrow abnormalities. The results of 74 patients with SDS (6 acute myeloid leukemia, 7 myelodysplastic syndrome, and 61 bone marrow failure) treated with HSCT between 1988 and 2016 are reported. The donor source was: 24% sibling, 8% parent, and 68% unrelated donor. The stem cell source was: 70% bone marrow, 19% peripheral blood stem cells, and 11% cord blood. The conditioning regimen was myeloablative in 54% and reduced intensity in 46%. Neutrophil engraftment was achieved in 84% of patients after a median time of 17.5 days. Graft failure occurred in 15% of HSCTs. Grades I-IV acute and chronic GVHD were observed in 55% and 20% of patients, respectively. After a median follow-up of 7.3 years (95% CI 4.8-10.2), 28 patients died for progression/relapse (7) or toxicity (21). The 5-year overall survival and nonrelapse mortality were 63.3% (95% CI 50.8-73.4) and 19.8% (95% CI 10.8-30.8), respectively. In conclusion, this is the largest series so far reported and confirms that HSCT is a suitable option for patients with SDS. Further efforts are needed to lower transplant-related toxicity and reduce graft failure.

mTOR and STAT3 Pathway Hyper-Activation is Associated with Elevated Interleukin-6 Levels in Patients with Shwachman-Diamond Syndrome: Further Evidence of Lymphoid Lineage Impairment

Shwachman–Diamond syndrome (SDS) is a rare inherited bone marrow failure syndrome, resulting in neutropenia and a risk of myeloid neoplasia. A mutation in a ribosome maturation factor accounts for almost all of the cases. Lymphoid involvement in SDS has not been well characterized. We recently reported that lymphocyte subpopulations are reduced in SDS patients. We have also shown that the mTOR-STAT3 pathway is hyper-activated in SDS myeloid cell populations. Here we show that mTOR-STAT3 signaling is markedly upregulated in the lymphoid compartment of SDS patients. Furthermore, our data reveal elevated IL-6 levels in cellular supernatants obtained from lymphoblasts, bone marrow mononuclear and mesenchymal stromal cells, and plasma samples obtained from a cohort of 10 patients. Of note, everolimus-mediated inhibition of mTOR signaling is associated with basal state of phosphorylated STAT3. Finally, inhibition of mTOR-STAT3 pathway activation leads to normalization of IL-6 expression in SDS cells. Altogether, our data strengthen the hypothesis that SDS affects both lymphoid and myeloid blood compartment and suggest everolimus as a potential therapeutic agent to reduce excessive mTOR-STAT3 activation in SDS.

Cellular and molecular architecture of hematopoietic stem cells and progenitors in genetic models of bone marrow failure

Inherited bone marrow failure syndromes, such as Fanconi anemia (FA) and Shwachman-Diamond syndrome (SDS), feature progressive cytopenia and a risk of acute myeloid leukemia (AML). Using deep phenotypic analysis of early progenitors in FA/SDS bone marrow samples, we revealed selective survival of progenitors that phenotypically resembled granulocyte-monocyte progenitors (GMP). Whole-exome and targeted sequencing of GMP-like cells in leukemia-free patients revealed a higher mutation load than in healthy controls and molecular changes that are characteristic of AML: increased G>A/C>T variants, decreased A>G/T>C variants, increased trinucleotide mutations at Xp(C>T)pT, and decreased mutation rates at Xp(C>T)pG sites compared with other Xp(C>T)pX sites and enrichment for Cancer Signature 1 (X indicates any nucleotide). Potential preleukemic targets in the GMP-like cells from patients with FA/SDS included SYNE1, DST, HUWE1, LRP2, NOTCH2, and TP53. Serial analysis of GMPs from an SDS patient who progressed to leukemia revealed a gradual increase in mutational burden, enrichment of G>A/C>T signature, and emergence of new clones. Interestingly, the molecular signature of marrow cells from 2 FA/SDS patients with leukemia was similar to that of FA/SDS patients without transformation. The predicted founding clones in SDS-derived AML harbored mutations in several genes, including TP53, while in FA-derived AML the mutated genes included ARID1B and SFPQ. We describe an architectural change in the hematopoietic hierarchy of FA/SDS with remarkable preservation of GMP-like populations harboring unique mutation signatures. GMP-like cells might represent a cellular reservoir for clonal evolution.

On-chip recapitulation of clinical bone marrow toxicities and patient-specific pathophysiology

The inaccessibility of living bone marrow hampers the study of its pathophysiology under myelotoxic stress induced by drugs, radiation or genetic mutations. Here, we show that a vascularized human bone-marrow-on-a-chip supports the differentiation and maturation of multiple blood-cell lineages over 4 weeks while improving CD34+ cell maintenance, and that it recapitulates aspects of marrow injury, including myeloerythroid toxicity after clinically relevant exposures to chemotherapeutic drugs and ionizing radiation as well as marrow recovery after drug-induced myelosuppression. The chip comprises a fluidic channel filled with a fibrin gel in which CD34⁺ cells and bone-marrow-derived stromal cells are co-cultured, a parallel channel lined by human vascular endothelium and perfused with culture medium, and a porous membrane separating the two channels. We also show that bone-marrow chips containing cells from patients with the rare genetic disorder Shwachman–Diamond syndrome reproduced key haematopoietic defects and led to the discovery of a neutrophil-maturation abnormality. As an in vitro model of haematopoietic dysfunction, the bone-marrow-on-a-chip may serve as a human-specific alternative to animal testing for the study of bone-marrow pathophysiology.

Genetic Basis of Myocarditis: Myth or Reality?

The genetic basis of myocarditis remains an intriguing concept, at least as long as the definition of myocarditis constitutes the definitive presence of myocardial inflammation sufficient to cause the observed ventricular dysfunction in the setting of cardiotropic infections. Autoimmune or immune-mediated myocardial inflammation constitutes a complex area of clinical interest, wherein numerous and not yet fully understood role of hereditary auto-inflammatory diseases can result in inflammation of the pericardium and myocardium. Finally, myocardial involvement in hereditary immunodeficiency diseases, cellular and humoral, is a possible trigger for infections which may complicate the diseases themselves. Whether the role of constitutional genetics can make the patient susceptible to myocardial inflammation remains yet to be explored.

Clinical features and outcomes of patients with Shwachman-Diamond syndrome and myelodysplastic syndrome or acute myeloid leukaemia: a multicentre, retrospective, cohort study

BACKGROUND

Data to inform surveillance and treatment for leukaemia predisposition syndromes are scarce and recommendations are largely based on expert opinion. This study aimed to investigate the clinical features and outcomes of patients with myelodysplastic syndrome or acute myeloid leukaemia and Shwachman-Diamond syndrome, an inherited bone marrow failure disorder with high risk of developing myeloid malignancies.

METHODS

We did a multicentre, retrospective, cohort study in collaboration with the North American Shwachman-Diamond Syndrome Registry. We reviewed patient medical records from 17 centres in the USA and Canada. Patients with a genetic (biallelic mutations in the SBDS gene) or clinical diagnosis (cytopenias and pancreatic dysfunction) of Shwachman-Diamond syndrome who developed myelodysplastic syndrome or acute myeloid leukaemia were eligible without additional restriction. Medical records were reviewed between March 1, 2001, and Oct 5, 2017. Masked central review of bone marrow pathology was done if available to confirm leukaemia or myelodysplastic syndrome diagnosis. We describe the clinical features and overall survival of these patients.

FINDINGS

We initially identified 37 patients with Shwachman-Diamond syndrome and myelodysplastic syndrome or acute myeloid leukaemia. 27 patients had samples available for central pathology review and were reclassified accordingly (central diagnosis concurred with local in 15 [56%] cases), 10 had no samples available and were classified based on the local review data, and 1 patient was excluded at this stage as not eligible. 36 patients were included in the analysis, of whom 10 (28%) initially presented with acute myeloid leukaemia and 26 (72%) initially presented with myelodysplastic syndrome. With a median follow-up of 4·9 years (IQR 3·9-8·4), median overall survival for patients with myelodysplastic syndrome was 7·7 years (95% CI 0·8-not reached) and 0·99 years (95% CI 0·2-2·4) for patients with acute myeloid leukaemia. Overall survival at 3 years was 11% (95% CI 1-39) for patients with leukaemia and 51% (29-68) for patients with myelodysplastic syndrome. Management and surveillance were variable. 18 (69%) of 26 patients with myelodysplastic syndrome received upfront therapy (14 haematopoietic stem cell transplantation and 4 chemotherapy), 4 (15%) patients received no treatment, 2 (8%) had unavailable data, and 2 (8%) progressed to acute myeloid leukaemia before receiving treatment. 12 patients received treatment for acute myeloid leukaemia-including the two patients initially diagnosed with myelodysplastic who progressed- two (16%) received HSCT as initial therapy and ten (83%) received chemotherapy with intent to proceed with HSCT. 33 (92%) of 36 patients (eight of ten with leukaemia and 25 of 26 with myelodysplastic syndrome) were known to have Shwachman-Diamond syndrome before development of a myeloid malignancy and could have been monitored with bone marrow surveillance. Bone marrow surveillance before myeloid malignancy diagnosis was done in three (33%) of nine patients with leukaemia for whom surveillance status was confirmed and 11 (46%) of 24 patients with myelodysplastic syndrome. Patients monitored had a 3-year overall survival of 62% (95% CI 32-82; n=14) compared with 28% (95% CI 10-50; n=19; p=0·13) without surveillance. Six (40%) of 15 patients with available longitudinal data developed myelodysplastic syndrome in the setting of stable blood counts.

INTERPRETATION

Our results suggest that prognosis is poor for patients with Shwachman-Diamond syndrome and myelodysplastic syndrome or acute myeloid leukaemia owing to both therapy-resistant disease and treatment-related toxicities. Improved surveillance algorithms and risk stratification tools, studies of clonal evolution, and prospective trials are needed to inform effective prevention and treatment strategies for leukaemia predisposition in patients with Shwachman-Diamond syndrome.

FUNDING

National Institute of Health.

Nordic Guidelines for Germline Predisposition to Myeloid Neoplasms in Adults: Recommendations for Genetic Diagnosis, Clinical Management and Follow-up

Myeloid neoplasms (MNs) with germline predisposition have recently been recognized as novel entities in the latest World Health Organization (WHO) classification for MNs. Individuals with MNs due to germline predisposition exhibit increased risk for the development of MNs, mainly acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS). Setting the diagnosis of MN with germline predisposition is of crucial clinical significance since it may tailor therapy, dictate the selection of donor for allogeneic hematopoietic stem cell transplantation (allo-HSCT), determine the conditioning regimen, enable relevant prophylactic measures and early intervention or contribute to avoid unnecessary or even harmful medication. Finally, it allows for genetic counseling and follow-up of at-risk family members. Identification of these patients in the clinical setting is challenging, as there is no consensus due to lack of evidence regarding the criteria defining the patients who should be tested for these conditions. In addition, even in cases with a strong suspicion of a MN with germline predisposition, no standard diagnostic algorithm is available. We present the first version of the Nordic recommendations for diagnostics, surveillance and management including considerations for allo-HSCT for patients and carriers of a germline mutation predisposing to the development of MNs.

Pancreatic Malnutrition in Children

Exocrine pancreatic insufficiency in children can lead to lifelong complications related to malnutrition and poor growth. The clinical presentation can be subtle in the early stages of insufficiency as the large functional capacity of the pancreas is gradually lost. The pediatrician plays a crucial role in the early identification of these children to ensure a timely referral so that a diagnosis can be made and therapy initiated. Early nutritional therapy allows for prevention and correction of deficiencies, which leads to improved outcomes and survival. When insufficiency is suspected, the workup should start with an indirect test of exocrine pancreatic function, such as fecal elastase, to establish the diagnosis. Once a diagnosis is established, further testing to delineate the etiology should be pursued, with cystic fibrosis being high on the differential list and assessed for with a sweat test. Assessment of anthropometry at every visit is key, as is monitoring of laboratory parameters and physical examination findings that are suggestive of malabsorption and malnutrition. The mainstay of management is administration of exogenous pancreatic enzymes to facilitate digestion and absorption. [Pediatr Ann. 2019;48(11):e441-e447.].

Hematological Malignancies in Adults With a Family Predisposition

BACKGROUND

Some hematological malignancies arise in persons with a hereditary predisposition. The hereditary nature of these diseases often goes unrecognized, particularly when symptoms begin in adulthood.

METHODS

This review is based on pertinent publications retrieved by a selective search in PubMed.

RESULTS

Many rare germline mutations have been identified that lead to acute leukemia and myelodysplastic syndromes. They differ from one another with respect to their penetrance, the age of onset of disease, and the clinical manifestations. In view of this heterogeneity, no uniform recommendations have yet been formulated for their diagnosis and treatment. The most common types of hematological malig- nancy with a hereditary predisposition are traceable to an underlying disturbance of DNA damage response and repair mechanisms and to mutations of hematological transcription factors. With regard to the selection of patients for testing, the con- sensus is that cytogenetic and molecular-genetic findings that are suspect for a hereditary predisposition, such as CEBPA and RUNX1 mutations, call for further investigation, as do any clinical features that are typical of tumor syndromes, or a positive family history. The knowledge that a hereditary predisposition may be present is highly stressful for patients; testing should only be carried out after the patient has received genetic counseling. The confirmation of a germline mutation always requires a comparison with healthy tissue. A fibroblast culture is recom- mended as the gold standard for this purpose.

CONCLUSION

The detection of a hereditary predisposition to hematological neoplasia is often relevant to treatment and follow-up care: for example, it may motivate early allogeneic stem-cell transplantation. Counseling, predictive testing, and follow-up care are available to the patients' relatives as well.

Shwachman-Diamond Syndrome: Molecular Mechanisms and Current Perspectives

Shwachman-Diamond syndrome (SDS) is a rare inherited disease mainly caused by mutations in the Shwachman-Bodian-Diamond Syndrome (SBDS) gene. However, it has recently been reported that other genes, including DnaJ heat shock protein family (Hsp40) member C21 (DNAJC21), elongation factor-like 1 (EFL1) and signal recognition particle 54 (SRP54) are also associated with an SDS-like phenotype. Interestingly, SBDS, DNAJC21, EFL1 and SRP54 are involved in ribosome biogenesis: SBDS, through direct interaction with EFL1, promotes the release of the eukaryotic initiation factor 6 (eIF6) during ribosome maturation, DNAJC21 stabilizes the 80S ribosome, and SRP54 facilitates protein trafficking. These findings strengthen the postulate that SDS is a ribosomopathy. SDS is a multiple-organ disease mainly characterized by bone marrow failure, bone malformations, pancreatic insufficiency and cognitive disorders. Almost 15-20% of patients with SDS present myelodysplastic syndrome with a high risk of acute myeloid leukemia (AML) transformation. Unfortunately, besides bone marrow transplantation, no gene-based therapy for SDS has yet been developed. This review aims to recapitulate the recent findings on the molecular mechanisms of SDS underlying bone marrow failure, hematopoiesis and AML development and to draw a realistic picture of current perspectives.

EFL1 mutations impair eIF6 release to cause Shwachman-Diamond syndrome

Shwachman-Diamond syndrome (SDS) is a recessive disorder typified by bone marrow failure and predisposition to hematological malignancies. SDS is predominantly caused by deficiency of the allosteric regulator Shwachman-Bodian-Diamond syndrome that cooperates with elongation factor-like GTPase 1 (EFL1) to catalyze release of the ribosome antiassociation factor eIF6 and activate translation. Here, we report biallelic mutations in EFL1 in 3 unrelated individuals with clinical features of SDS. Cellular defects in these individuals include impaired ribosomal subunit joining and attenuated global protein translation as a consequence of defective eIF6 eviction. In mice, Efl1 deficiency recapitulates key aspects of the SDS phenotype. By identifying biallelic EFL1 mutations in SDS, we define this leukemia predisposition disorder as a ribosomopathy that is caused by corruption of a fundamental, conserved mechanism, which licenses entry of the large ribosomal subunit into translation.

Somatic mutation panels: Time to clear their names

With improvements in DNA sequencing technologies and the consequent reduction in costs, next generation sequencing is being utilized increasingly in panel-based testing to perform molecular profiling of tumors. Such tumor-based panels are often referred to as 'somatic' panels, but this term is misleading and should not be used, since not all DNA variants within a tumor are somatic in nature. Every cell in a person's body contains that person's germline DNA, including tumor cells. Moreover, tumor samples are invariably contaminated with blood, a tissue that can contain somatic mutations itself in a process now called clonal hematopoiesis. Differentiating between germline variants or tumor-associated somatic mutations versus clonal hematopoiesis can be challenging. In this review, we address how to interpret the results of somatic mutation panels, how to differentiate between germline and truly somatic events, and discuss the importance of this distinction.

Neutropenia in the age of genetic testing: Advances and challenges

Identification of genetic causes of neutropenia informs precision medicine approaches to medical management and treatment. Accurate diagnosis of genetic neutropenia disorders informs treatment options, enables risk stratification, cancer surveillance, and attention to associated medical complications. The rapidly expanding genetic testing options for the evaluation of neutropenia have led to exciting advances but also new challenges. This review provides a practical guide to germline genetic testing for neutropenia.

Normative growth charts for Shwachman-Diamond syndrome from Italian cohort of 0-8 years old

OBJECTIVES

Shwachman-Diamond syndrome (SDS) is a rare autosomal recessive disorder. Its predominant manifestations include exocrine pancreatic insufficiency, bone marrow failure and skeletal abnormalities. Patients frequently present failure to thrive and susceptibility to short stature. Average birth weight is at the 25th percentile; by the first birthday, >50% of patients drop below the third percentile for height and weight.The study aims at estimating the growth charts for patients affected by SDS in order to give a reference tool helpful for medical care and growth surveillance through the first 8 years of patient's life.

SETTING AND PARTICIPANTS

This retrospective observational study includes 106 patients (64 M) with available information from birth to 8 years, selected among the 122 patients included in the Italian National Registry of SDS and born between 1975 and 2016. Gender, birth date and auxological parameters at repeated assessment times were collected. The General Additive Model for Location Scale and Shape method was applied to build the growth charts. A set of different distributions was used, and the more appropriate were selected in accordance with the smallest Akaike information criterion.

RESULTS

A total of 408 measurements was collected and analysed. The median number of observations per patient amounted to 3, range 1-11. In accordance with the methods described, specific SDS growth charts were built for weight, height and body mass index (BMI), separately for boys and girls.The 50th and 3rd percentiles of weight and height of the healthy population (WHO standard references) respectively correspond to the 97th and 50th percentiles of the SDS population (SDS specific growth charts), while the difference is less evident for the BMI.

CONCLUSIONS

Specific SDS growth charts obtained through our analysis enable a more appropriate classification of patients based on auxological parameters, representing a useful reference tool for evaluating their growth during childhood.

Peering through zebrafish to understand inherited bone marrow failure syndromes

Inherited bone marrow failure syndromes are experiments of nature characterized by impaired hematopoiesis with cancer and leukemia predisposition. The mutations associated with inherited bone marrow failure syndromes affect fundamental cellular pathways, such as DNA repair, telomere maintenance, or proteostasis. How these disturbed pathways fail to produce sufficient blood cells and lead to leukemogenesis are not understood. The rarity of inherited cytopenias, the paucity of affected primary human hematopoietic cells, and the sometime inadequacy of murine or induced pluripotential stem cell models mean it is difficult to acquire a greater understanding of them. Zebrafish offer a model organism to study gene functions. As vertebrates, zebrafish share with humans many orthologous genes involved in blood disorders. As a model organism, zebrafish provide advantages that include rapid development of transparent embryos, high fecundity (providing large numbers of mutant and normal siblings), and a large collection of mutant and transgenic lines useful for investigating the blood system and other tissues during development. Importantly, recent advances in genomic editing in zebrafish can speedily validate the new genes or novel variants discovered in clinical investigation as causes for marrow failure. Here we review zebrafish as a model organism that phenocopies Fanconi anemia, Diamond-Blackfan anemia, dyskeratosis congenita, Shwachman-Diamond syndrome, congenital amegakaryocytic thrombocytopenia, and severe congenital neutropenia. Two important insights, provided by modeling inherited cytopenias in zebrafish, widen understanding of ribosome biogenesis and TP53 in mediating marrow failure and non-hematologic defects. They suggest that TP53-independent pathways contribute to marrow failure. In addition, zebrafish provide an attractive model organism for drug development.

Interaction of the GTPase Elongation Factor Like-1 with the Shwachman-Diamond Syndrome Protein and Its Missense Mutations

The Shwachman-Diamond Syndrome (SDS) is a disorder arising from mutations in the genes encoding for the Shwachman-Bodian-Diamond Syndrome (SBDS) protein and the GTPase known as Elongation Factor Like-1 (EFL1). Together, these proteins remove the anti-association factor eIF6 from the surface of the pre-60S ribosomal subunit to promote the formation of mature ribosomes. SBDS missense mutations can either destabilize the protein fold or affect surface epitopes. The molecular alterations resulting from the latter remain largely unknown, although some evidence suggest that binding to EFL1 may be affected. We further explored the effect of these SBDS mutations on the interaction with EFL1, and showed that all tested mutations disrupted the binding to EFL1. Binding was either severely weakened or almost abolished, depending on the assessed mutation. In higher eukaryotes, SBDS is essential for development, and lack of the protein results in early lethality. The existence of patients whose only source of SBDS consists of that with surface missense mutations highlights the importance of the interaction with EFL1 for their function. Additionally, we studied the interaction mechanism of the proteins in solution and demonstrated that binding consists of two independent and cooperative events, with domains 2⁻3 of SBDS directing the initial interaction with EFL1, followed by docking of domain 1. In solution, both proteins exhibited large flexibility and consisted of an ensemble of conformations, as demonstrated by Small Angle X-ray Scattering (SAXS) experiments.

Further evidence for the involvement of EFL1 in a Shwachman-Diamond-like syndrome and expansion of the phenotypic features

Recent evidence has implicated EFL1 in a phenotype overlapping Shwachman-Diamond syndrome (SDS), with the functional interplay between EFL1 and the previously known causative gene SBDS accounting for the similarity in clinical features. Relatively little is known about the phenotypes associated with pathogenic variants in the EFL1 gene, but the initial indication was that phenotypes may be more severe, when compared with SDS. We report a pediatric patient who presented with a metaphyseal dysplasia and was found to have biallelic variants in EFL1 on reanalysis of trio whole-exome sequencing data. The variant had not been initially reported because of the research laboratory's focus on de novo variants. Subsequent phenotyping revealed variability in her manifestations. Although her metaphyseal abnormalities were more severe than in the original reported cohort with EFL1 variants, the bone marrow abnormalities were generally mild, and there was equivocal evidence for pancreatic insufficiency. Despite the limited number of reported patients, variants in EFL1 appear to cause a broader spectrum of symptoms that overlap with those seen in SDS. Our report adds to the evidence of EFL1 being associated with an SDS-like phenotype and provides information adding to our understanding of the phenotypic variability of this disorder. Our report also highlights the value of exome data reanalysis when a diagnosis is not initially apparent.

An update on the pathogenesis and diagnosis of Diamond-Blackfan anemia

Diamond–Blackfan anemia (DBA) is a rare congenital hypoplastic anemia characterized by a block in erythropoiesis at the progenitor stage, although the exact stage at which this occurs remains to be fully defined. DBA presents primarily during infancy with macrocytic anemia and reticulocytopenia with 50% of cases associated with a variety of congenital malformations. DBA is most frequently due to a sporadic mutation (55%) in genes encoding several different ribosomal proteins, although there are many cases where there is a family history of the disease with varying phenotypes. The erythroid tropism of the disease is still a matter of debate for a disease related to a defect in global ribosome biogenesis. Assessment of biological features in conjunction with genetic testing has increased the accuracy of the diagnosis of DBA. However, in certain cases, it continues to be difficult to firmly establish a diagnosis. This review will focus on the diagnosis of DBA along with a description of new advances in our understanding of the pathophysiology and treatment recommendations for DBA.

Shwachman-Diamond syndrome: Nationwide survey and systematic review in Japan

BACKGROUND

Shwachman-Diamond syndrome (SDS) is a rare multisystem disorder associated with exocrine pancreatic insufficiency. The present study reports the results of a nationwide survey and a systematic review on SDS to develop consensus guidelines for intractable diarrhea including SDS.

METHODS

Questionnaires were sent to 616 departments of pediatrics or of pediatric surgery in Japan in a nationwide survey. A second questionnaire was sent to doctors who had treated SDS patients and included questions on clinical information. Additionally, a systematic review was performed using digital literature databases to assess the influence of medical (i.e. non-surgical) treatment on SDS prognosis.

RESULTS

Answers were received from 529 institutions (85.9%), which included information on 24 patients with SDS (median age, 10.4 years; male, n = 15) treated from January 2005 to December 2014. Although 75% of patients received pancreatic enzyme replacement therapy, there was no significant association between treatment and prognosis. Systematic review identified one clinical practice guideline, two case series, eight case reports and 26 reviews. Patient information from those studies was insufficient for meta-analysis.

CONCLUSIONS

The rarity of SDS makes it difficult to establish evidence-based treatment for SDS. According to the limited information from patients and published reports, medical treatment for malabsorption due to SDS should be performed to improve fat absorption and stool condition, but it is not clear whether this treatment improves the prognosis of malabsorption.

The histopathology of bone marrow failure in children

Bone marrow failure (BMF) is a rare but life-threatening disorder that usually manifests as (pan)cytopenia. BMF can be caused by a variety of diseases, but inherited BMF (IBMF) syndromes are a clinically important cause, especially in children. IBMF syndromes are a heterogeneous group of genetic disorders characterized by BMF, physical abnormalities, and predisposition to malignancy. An accurate diagnosis is critical, as disease-specific management, surveillance, and genetic counselling are required for each patient. The major differential diagnoses of IBMF syndromes are acquired aplastic anemia (AA) and refractory cytopenia of childhood (RCC). These diseases have overlapping features, such as BM hypocellularity and/or dysplastic changes, which make the differential diagnosis challenging. RCC has been defined as a histomorphologically distinct entity. Therefore, understanding the BM histopathology of these diseases is essential for the differential diagnosis. However, the BM histopathological features have not been characterized in detail, as descriptions of BM histopathology are very limited due to the rarity of the diseases. This review provides a detailed description of the BM histopathology in cases of RCC, AA, and the four most common IBMF syndromes: Fanconi anemia (FA), dysketatosis congenita (DC), Diamond-Blackfan anemia (DBA), and Shwachman-Diamond syndrome (SDS). An overview, including the clinical features and diagnosis, is also provided.

Liver transplantation for very severe hepatopulmonary syndrome due to vitamin A-induced chronic liver disease in a patient with Shwachman-Diamond syndrome

Vitamin A intoxication is a rare cause of liver disease, but the risk increases in patients with underlying liver dysfunction. We present a patient with Shwachman-Diamond Syndrome who developed liver fibrosis, portal hypertension and very severe hepatopulmonary syndrome as a consequence of chronic vitamin A intoxication. She underwent successful liver transplantation with complete resolution of the pulmonary shunting.

Recommendations for Surveillance for Children with Leukemia-Predisposing Conditions

Leukemia, the most common childhood cancer, has long been recognized to occasionally run in families. The first clues about the genetic mechanisms underlying familial leukemia emerged in 1990 when Li-Fraumeni syndrome was linked to TP53 mutations. Since this discovery, many other genes associated with hereditary predisposition to leukemia have been identified. Although several of these disorders also predispose individuals to solid tumors, certain conditions exist in which individuals are specifically at increased risk to develop myelodysplastic syndrome (MDS) and/or acute leukemia. The increasing identification of affected individuals and families has raised questions around the efficacy, timing, and optimal methods of surveillance. As part of the AACR Childhood Cancer Predisposition Workshop, an expert panel met to review the spectrum of leukemia-predisposing conditions, with the aim to develop consensus recommendations for surveillance for pediatric patients. The panel recognized that for several conditions, routine monitoring with complete blood counts and bone marrow evaluations is essential to identify disease evolution and enable early intervention with allogeneic hematopoietic stem cell transplantation. However, for others, less intensive surveillance may be considered. Because few reports describing the efficacy of surveillance exist, the recommendations derived by this panel are based on opinion, and local experience and will need to be revised over time. The development of registries and clinical trials is urgently needed to enhance understanding of the natural history of the leukemia-predisposing conditions, such that these surveillance recommendations can be optimized to further enhance long-term outcomes. Clin Cancer Res; 23(11); e14-e22. ©2017 AACRSee all articles in the online-only CCR Pediatric Oncology Series.

Fanconi anaemia and cancer: an intricate relationship

Fanconi anaemia (FA) is a genetic disorder that is characterized by bone marrow failure (BMF), developmental abnormalities and predisposition to cancer. Together with other proteins involved in DNA repair processes and cell division, the FA proteins maintain genome homeostasis, and germline mutation of any one of the genes that encode FA proteins causes FA. Monoallelic inactivation of some FA genes, such as FA complementation group D1 (FANCD1; also known as the breast and ovarian cancer susceptibility gene BRCA2), leads to adult-onset cancer predisposition but does not cause FA, and somatic mutations in FA genes occur in cancers in the general population. Carcinogenesis resulting from a dysregulated FA pathway is multifaceted, as FA proteins monitor multiple complementary genome-surveillance checkpoints throughout interphase, where monoubiquitylation of the FANCD2-FANCI heterodimer by the FA core complex promotes recruitment of DNA repair effectors to chromatin lesions to resolve DNA damage and mitosis. In this Review, we discuss how the FA pathway safeguards genome integrity throughout the cell cycle and show how studies of FA have revealed opportunities to develop rational therapeutics for this genetic disease and for malignancies that acquire somatic mutations within the FA pathway.

Pediatric leukemia susceptibility disorders: manifestations and management

The clinical manifestations of inherited susceptibility to leukemia encompass a wide phenotypic range, including patients with certain congenital anomalies or early-onset myelodysplastic syndrome (MDS) and some with no obvious medical problems until they develop leukemia. Leukemia susceptibility syndromes occur as a result of autosomal dominant, autosomal recessive, or X-linked recessive inheritance, or de novo occurrence, of germline pathogenic variants in DNA repair, ribosome biogenesis, telomere biology, hematopoietic transcription factors, tumor suppressors, and other critical cellular processes. Children and adults with cytopenias, MDS, dysmorphic features, notable infectious histories, immunodeficiency, certain dermatologic findings, lymphedema, unusual sensitivity to radiation or chemotherapy, or acute leukemia with a family history of early-onset cancer, pulmonary fibrosis, or alveolar proteinosis should be thoroughly evaluated for a leukemia susceptibility syndrome. Genetic testing and other diagnostic modalities have improved our ability to identify these patients and to counsel them and their family members for subsequent disease risk, cancer surveillance, and therapeutic interventions. Herein, the leukemia susceptibility syndromes are divided into 3 groups: (1) those associated with an underlying inherited bone marrow failure syndrome, (2) disorders in which MDS precedes leukemia development, and (3) those with a risk primarily of leukemia. Although children are the focus of this review, it is important for clinicians to recognize that inherited susceptibility to cancer can present at any age, even in older adults; genetic counseling is essential and prompt referral to experts in each syndrome is strongly recommended.

Treatment of inherited bone marrow failure syndromes beyond transplantation

Despite significant progress in transplantation by the addition of alternative hematopoietic stem cell sources, many patients with inherited bone marrow failure syndromes are still not eligible for a transplant. In addition, the availability of sequencing panels has significantly improved diagnosis by identifying cryptic inherited cases. Androgens are the main nontransplant therapy for bone marrow failure in dyskeratosis congenita and Fanconi anemia, reaching responses in up to 80% of cases. Danazol and oxymetholone are more commonly used, but virilization and liver toxicity are major adverse events. Diamond-Blackfan anemia is commonly treated with corticosteroids, but most patients eventually become refractory to this treatment and toxicity is limiting. Growth factors still have a role in inherited cases, especially granulocyte colony-stimulating factor in congenital neutropenias. Novel therapies are warranted and thrombopoietin receptor agonists, leucine, quercetin, and novel gene therapy approaches may benefit inherited cases in the future.

Association of isochromosome (7)(q10) in Shwachman-Diamond syndrome with the severity of cytopenia

We report two male siblings with SDS. They have the same compound heterozygous mutations. Only one of the siblings acquired cytogenetic abnormality of i(7q) 2 years after diagnosis, became transfusion-dependent, and underwent allogeneic hematopoietic stem cell transplantation. These cases indicate that i(7q) is associated with significant cytopenia in SDS patients.

Short stature: an ordinary sign for an unordinary diagnosis

Background

Case presentation

Conclusions

The Greek Registry of Shwachman Diamond-Syndrome: Molecular and clinical data

This study presents the clinical phenotype and molecular analysis findings from 11 patients recorded in the Greek Shwachman-Diamond syndrome (SDS) Registry. The most severely affected patient in our registry was diagnosed at birth and is the first patient reported to require bone marrow transplantation so early in life. Severe psoriasis, a feature not previously reported in SDS, was observed in one patient. Mutations in the Shwachman-Bodian-Diamond syndrome gene (SBDS) were found in all patients. Cytogenetic analyses revealed clonal abnormalities, one novel, in two patients.

Inherited Bone Failure Syndromes, Focus on the Haematological Manifestations: A Review

The purpose of this review is to provide the haematologist with a working knowledge of the common inherited bone marrow failure syndromes (iBMFS) diagnosed in early childhood to young adulthood. Although these disorders are heterogeneous, this article discusses their common features, pathophysiology, and management. Each of these syndromes has a spectrum of clinical variation and can cause both haematological and non-haematological manifestations. Most pathogenic mutations responsible are in genes important to a progenitor cell’s ability to maintain genomic integrity, which accounts for the clinical phenotypes often affecting multiple tissues. Furthermore, all of these syndromes predispose not only to aplastic anaemia but also to myelodysplastic syndrome/acute myeloid leukaemia. Since iBMFS only account for a small percentage of childhood leukaemia cases, it is important that the clinician maintains a high clinical suspicion as appropriate diagnosis impacts treatment, health screening, and family members. Identification of iBMFS is critically important for appropriate donor selection and transplant regimens, as haematopoietic stem cell transplantation is curative for the haematological manifestations of these diseases, but treatment-related mortality can be excessive if modifications are not made to conditioning.

Genetic predisposition to hematologic malignancies: management and surveillance

As individuals with germ line predisposition to hematologic malignancies are diagnosed with increasing frequency, the need for clinical surveillance has become apparent. Unfortunately, few prospective data are available, so recommendations are based on collective experience and expert consensus. There is general agreement to advocate for expert consultation or referral of patients to centers with expertise in these syndromes, since presentations and disease progression can be subtle, and treatment strategies must be tailored. Here, we summarize and integrate expert consensus recommendations and medical management considerations for the patient newly diagnosed with a leukemia predisposition disorder. Indications to consider additional studies and referral for allogeneic stem cell transplantation are also discussed.

Pancreatic Disorders

Once considered uncommon, pancreatic diseases are increasingly recognized in the pediatric age group. Acute pancreatitis, acute recurrent pancreatitis, and chronic pancreatitis occur in children with an incidence approaching that of adults. Risk factors are broad, prompting the need for a completely different diagnostic and therapeutic approach in children. Although cystic fibrosis remains the most common cause of exocrine pancreatic insufficiency, other causes such as chronic pancreatitis may be as common as Shwachman Diamond syndrome. Long-term effects of pancreatic diseases may be staggering, as children suffer from significant disease burden, high economic cost, nutritional deficiencies, pancreatogenic diabetes, and potentially pancreatic cancer.

How I manage children with neutropenia

Neutropenia, usually defined as a blood neutrophil count <1·5 × 10⁹ /l, is a common medical problem for children and adults. There are many causes for neutropenia, and at each stage in life the clinical pattern of causes and consequences differs significantly. I recommend utilizing the age of the child and clinical observations for the preliminary diagnosis and primary management. In premature infants, neutropenia is quite common and contributes to the risk of sepsis with necrotizing enterocolitis. At birth and for the first few months of life, neutropenia is often attributable to isoimmune or alloimmune mechanisms and predisposes to the risk of severe bacterial infections. Thereafter when a child is discovered to have neutropenia, often associated with relatively minor symptoms, it is usually attributed to autoimmune disorder or viral infection. The congenital neutropenia syndromes are usually recognized when there are recurrent infections, the neutropenia is severe and there are congenital anomalies suggesting a genetic disorder. This review focuses on the key clinical finding and laboratory tests for diagnosis with commentaries on treatment, particularly the use of granulocyte colony-stimulating factor to treat childhood neutropenia.

Classical inherited bone marrow failure syndromes with high risk for myelodysplastic syndrome and acute myelogenous leukemia

The inherited marrow failure syndromes (IBMFS) are a heterogeneous group of diseases characterized by failure in the production of one or more blood lineage. The clinical manifestations of the IBMFS vary according to the type and number of blood cell lines involved, including different combinations of anemia, leukopenia, and thrombocytopenia. In some IBMFS, systemic non-hematologic manifestations, including congenital malformations, mucocutaneous abnormalities, developmental delay, and other medical complications, may be present. Fanconi anemia (FA), caused by germline pathogenic variants in the DNA repair genes comprising the FA/BRCA pathway is associated with congenital anomalies, bone marrow failure, and increased risk of myelodysplastic syndrome (MDS), acute myelogenous leukemia (AML), and solid tumors. Dyskeratosis congenita (DC) is a telomere biology disorder (TBD) caused by aberrations in key telomere biology genes. In addition to mucocutaneous manifestations, patients with DC are at increased risk of marrow failure, MDS, AML, pulmonary fibrosis, and other complications. Ribosomal biology defects are the primary causes of Diamond Blackfan anemia (DBA) and Shwachman Diamond syndrome (SDS). In addition to pure red blood cell aplasia, DBA is associated with elevated risk of solid tumors, AML, and MDS. Patients with SDS have pancreatic insufficiency, neutropenia, as well as MDS and AML risks. Patients with severe congenital neutropenia (SCN), caused by pathogenic variants in genes essential in myeloid development, have profound neutropenia and high risk of MDS and AML. Herein we review the genetic causes, clinical features, diagnostic modalities, predisposition to malignancies with focus on leukemogenic markers whenever available, and approaches to treatments of the classical IBMFS: FA, DC, SDS, DBA, and SCN.

First experience of hematopoietic stem cell transplantation treatment of Shwachman-Diamond syndrome using unaffected HLA-matched sibling donor produced through preimplantation HLA typing

The only proven cure for Shwachman-Diamond syndrome (SDS) bone marrow failure is allogeneic hematopoietic stem cell transplantation (HSCT). However HSCT with donors other than HLA-identical siblings is associated with high mortality and unfavorable prognosis. This paper presents the first experience of HSCT treatment of SDS using an unaffected HLA-identical sibling produced through preimplantation genetic diagnosis (PGD). The patient was a 6-year-old blood transfusion-dependent SDS baby girl with secondary myelodysplastic syndrome, for whom no HLA-identical donor was available. As a result of PGD, two unaffected HLA matched embryos were identified; one of them was randomly selected for transfer, resulting in a clinical pregnancy and birth of an apparently healthy child. The patient underwent allogeneic transplantation of cord blood hematopoietic stem cells, together with bone marrow from this sibling, resulting in complete hemopoietic recovery. The patient was no longer transfusion-dependent and had normal blood values 160 days after transplantation.

Germline Genetic Predisposition to Hematologic Malignancy

Development of hematologic malignancies is driven by mutations that may be somatic or germline. Availability of next-generation DNA sequencing technologies has facilitated the development of individualized diagnostic evaluations and tailored treatment strategies. Until now, such personalized medical approaches have largely centered on prognostic stratification and treatment strategies informed by acquired somatic mutations. The role of germline mutations in children and adults with hematologic malignancies was previously underappreciated. Diagnosis of an inherited predisposition to hematologic malignancy informs choice of therapy, risk of treatment-related complications, donor selection for hematopoietic stem cell transplantation, evaluation of comorbidities, and surveillance strategies to improve clinical outcomes. The recognition that patients with inherited hematologic malignancy syndromes may present without classic clinical stigmata or suspicious family history has led to increased reliance on genetic testing, which, in turn, has raised new diagnostic challenges. Genomic testing is a rapidly evolving field with an increasing number of choices for testing for the practicing clinician to navigate. This review will discuss general approaches to diagnosis and management of patients with germline predisposition to hematology malignancies and will consider applications and limitations of genomic testing in clinical practice.

Biallelic mutations in DNAJC21 cause Shwachman-Diamond syndrome

There is an Inside Blood Commentary on this article in this issue.