Bone marrow (BM) failure (BMF) in children and young adults is often suspected to be inherited, but in many cases diagnosis remains uncertain. We studied a cohort of 179 patients (from 173 families) with BMF of suspected inherited origin but unresolved diagnosis after medical evaluation and Fanconi anemia exclusion. All patients had cytopenias, and 12.0% presented ≥5% BM blast cells. Median age at genetic evaluation was 11 years; 20.7% of patients were aged ≤2 years and 36.9% were ≥18 years. We analyzed genomic DNA from skin fibroblasts using whole-exome sequencing, and were able to assign a causal or likely causal germ line mutation in 86 patients (48.0%), involving a total of 28 genes. These included genes in familial hematopoietic disorders (, ), telomeropathies (, ,), ribosome disorders (, ,), and DNA repair deficiency (). Many patients had an atypical presentation, and the mutated gene was often not clinically suspected. We also found mutations in genes seldom reported in inherited BMF (IBMF), such as and (N = 16 of the 86 patients, 18.6%), (N = 6, 7.0%), and (N = 7, 8.1%), each of which was associated with a distinct natural history; and patients often experienced transient aplasia and monosomy 7, whereas patients presented early-onset severe aplastic anemia, and patients, mild pancytopenia with myelodysplasia. This study broadens the molecular and clinical portrait of IBMF syndromes and sheds light on newly recognized disease entities. Using a high-throughput sequencing screen to implement precision medicine at diagnosis can improve patient management and family counseling.

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Osteomyelitis often causes functional impairment due to tissue destruction. This report demonstrates a novel previously unappreciated role of osteoblasts. Samples of osteomyelitic bone and bacterially challenged osteoblasts produce increased amounts of antimicrobial peptides in order to combat bacterial bone infection. An osteomyelitis mouse model confirmed the osseous induction of the murine homologue of human β -defensin-2, suggesting a central role in the prevention of bacterial bone infection. Antimicrobial peptides are effectors of the innate defence system and play a key role in host protection at cellular surfaces. Some of them are produced constitutively, whereas others are induced during infection. Human β -defensins represent a major subclass of antimicrobial peptides and act as a first line of defence through their broad spectrum of potent antimicrobial activity. The aim of the present in-vitro and in-vivo investigations was to study the expression and regulation of human β -defensin-2 in the case of bacterial bone infection and to analyse the effects of immunosuppressive drugs on bone-derived antimicrobial peptide expression. Samples of healthy human bone, osteomyelitic bone and cultured osteoblasts (hFOB cells) were assessed for the expression of human β -defensin-2. Regulation of human β -defensin-2 was studied in hFOB cells after exposure to bacterial supernatants, proinflammatory cytokines and immunosuppressive drugs (glucocorticoids and methotrexate) and was assayed by enzyme-linked immunosorbent assay. An osteomyelitis mouse model was performed to demonstrate the regulation of the murine homologue of human β -defensin-2, named murine β -defensin-3, by real-time reverse transcription-polymerase chain reaction and immunohistochemistry. Healthy human bone and cultured osteoblasts are able to produce human β -defensin-2 under standard conditions. Samples of infected bone produce higher levels of endogenous antibiotics, such as human β -defensin-2, when compared with samples of healthy bone. A clear induction of human β -defensin-2 was observed after exposure of cultured osteoblasts to Gram-positive bacteria or proinflammatory cytokines. Additional treatment with glucocorticoids or methotrexate prevented bacteria-mediated antimicrobial peptide induction in cultured osteoblasts. The osteomyelitis mouse model demonstrated transcriptional upregulation of the murine homologue of human β -defensin-2, namely murine β -defensin-3, in bone after intraosseous contamination of the tibia. Human and murine bone have the ability to produce broad-spectrum endogenous antibiotics when challenged by microorganisms in vitro and in vivo . Immunosuppressive drugs, such as glucocorticoids or methotrexate, may increase the susceptibility to bone infection by decreasing antimicrobial peptide expression levels in case of microbial challenge. The induction of human β -defensin-2 following bacterial contact suggests a central role of antimicrobial peptides in the prevention of bacterial bone infection.

The telomere complex consists of repetitive DNA sequences and associated proteins and is located at the end of eukaryotic chromosomes. Telomeres shorten with every cell division and thereby both reflect and restrict the proliferative capacity of somatic cells. Critically short telomeres are associated with genetic instability and eventually, replicative senescence. In chronic myeloid leukemia (CML), increased cellular turnover of clonal breakpoint cluster region-Abelson Murine Leukemia Viral Oncogene Homolog 1 (BCR-ABL)-positive hematopoietic stem and progenitor cells leads to significantly shortened telomeres in peripheral blood myeloid cells. 1 Accelerated telomere shortening was found to correlate with disease stage, cytogenetic remission status, progression to accelerated phase and blast crisis as well as clinical risk score at diagnosis in retrospective trials (refs 1-3, reviewed in ref. 4). However, whether telomere length (TL) can be used as prognostic indicator and/or to predict for depth and kinetics of response to tyrosine kinase inhibitor therapy in patients with CML has not been studied prospectively to date. Consequently, the aim of this substudy within the ENEST1st trial (NCT01061177) was to investigate, whether average TL in peripheral blood leukocytes at diagnosis measured by monochrome multiplex quantitative PCR (MM-qPCR) can be used as an independent prognostic and/or predictive biomarker in patients with CML undergoing first-line treatment with nilotinib. TL from 96 newly diagnosed CML patients before treatment initiation within the ENEST1st trial was measured using MM-qPCR and results were expressed as the standardized T/S ratio. 5 One extreme outlier was excluded from the analysis. Age adaption of TL, indicated as ΔT/S ratio, was performed using data from 89 healthy controls, representing blood donors. 6 The average intra-assay variability expressed as CV Intra-assay for all samples (n = 184; control and CML samples included) was 10.5%. In addition, to monitor plate-to-plate variation, eight reference blood samples from healthy volunteers (age range 24-83 years) were included in each run. The resulting average CV Inter-assay for all eight reference samples was 15.3%. Characteristics of healthy controls and patients are shown in Supplementary Material. The 89 control individuals (unfilled circles, Figure 1a) showed the expected decline in TL with increasing age-a characteristic no longer detectable in CML patients (filled circles). Mean age adjusted TL (ΔT/S ratio) of CML patients was more spread within different age groups and significantly shorter (ΔT/S: − 0.3097 ± 0.6644, n = 95, Po0.001). This is in line with previous studies suggesting accelerated telomere shortening in CML mostly due to an increased turnover of the leukemic as opposed to the coexisting normal stem cell compartment (ref. 1, reviewed in ref. 7). Of note, the analysis of ΔT/S versus age resulted in a positive correlation, indicating a more pronounced TL deficit in younger CML patients (P = 0.0017).

Key Points B-PLL is tightly linked to MYC aberrations (translocation or gain) and 17p (TP53) deletion. Cases of B-PLL with MYC aberration and 17p (TP53) deletion have the worst prognosis.

Nile tilapia ( Oreochromis niloticus ) is an African freshwater fish that displays a genetic sex determination system (XX|XY) where high temperatures (above 32°C to 36.5°C) induce masculinization. In Nile tilapia, the thermosensitive period was reported from 10 to 30 days post fertilization. In their natural environment, juveniles may encounter high temperatures that are above the optimal temperature for growth (27–30°C). The relevance of the thermal sex reversal mechanism in a natural context remains unclear. The main objective of our study is to determine whether sexually undifferentiated juveniles spontaneously prefer higher, unfavorable temperatures and whether this choice skews the sex ratio toward males. Five full-sib progenies (from 100% XX crosses) were subjected to (1) a horizontal three-compartment thermal step gradient (thermal continuum 28°C– 32°C– 36.5°C) during the thermosensitive period, (2) a control continuum (28°C– 28°C– 28°C) and (3) a thermal control tank (36.5°C). During the first days of the treatment, up to an average of 20% of the population preferred the masculinizing compartment of the thermal continuum (36.5°C) compared to the control continuum. During the second part of the treatment, juveniles preferred the lower, nonmasculinizing 32°C temperature. This short exposure to higher temperatures was sufficient to significantly skew the sex ratio toward males, compared to congeners raised at 28°C (from 5.0 ± 6.7% to 15.6 ± 16.5% of males). The proportion of males was significantly different in the thermal continuum, thermal control tank and control continuum, and it was positively correlated among populations. Our study shows for the first time that Nile tilapia juveniles can choose a masculinizing temperature during a short period of time. This preference is sufficient to induce sex reversal to males within a population. For the first time, behavior is reported as a potential player in the sex determination mechanism of this species.

Bone mineral deposition during the modeling of new bone and remodeling of old bone can be perturbed by several pathological conditions, including osteoporosis and skeletal metastases. A site-specific marker depicting the dynamics of bone mineral deposition would provide insight into skeletal disease location and severity, and prove useful in evaluating the efficacy of pharmacological interventions. Fluorescent labels may combine advantages of both radioisotope imaging and detailed microscopic analyses. The purpose of this study was to determine if the fluorescent bisphosphonate OsteoSense could detect localized changes in bone mineral deposition in established mouse models of accelerated bone loss (ovariectomy) (OVX) and anabolic bone gain resulting from parathyroid hormone (PTH) treatment. We hypothesized that the early rate of binding, as well as the total amount of bisphosphonate, which binds over long periods of time, could be useful in evaluating changes in bone metabolism. Evaluation of the kinetic uptake of bisphosphonates revealed a significant reduction in both the rate constant and plateau binding after OVX, whereas treatment with PTH resulted in a 36-fold increase in the bisphosphonate binding rate constant compared with untreated OVX controls. Localization of bisphosphonate binding revealed initial binding at sites of ossification adjacent to the growth plate and, to a lesser extent, along more distal trabecular and cortical elements. Micro-computed tomography (CT) was used to confirm that initial bisphosphonate binding is localized to sites of low tissue mineral density, associated with new bone mineral deposition. Our results suggest monitoring binding kinetics based on fluorescently labeled bisphosphonates represents a highly sensitive, site-specific method for monitoring changes in bone mineral deposition with the potential for translation into human applications in osteoporosis and bone metastatic processes and their treatment.