The Complex Network of Cytokines and Chemokines in Pediatric Patients with Long-Standing Type 1 Diabetes.

Type 1 diabetes (T1D) is a progressive disorder leading to the development of microangiopathies and macroangiopathies. Numerous cytokines and chemokines are involved in the pathogenesis of T1D complications. The study aimed to assess the presence of complications in patients with long-standing T1D and its relationship with serum biomarker concentrations. We examined 52 T1D subjects, with a disease duration ≥4 years and 39 healthy controls. The group of T1D patients was further divided into subgroups based on the duration of the disease (<7 years and ≥7 years) and the metabolic control assessed by the HbAlc level (<8% and ≥8%). We used Luminex Technology to assess a wide range of biomarker concentrations. A 24 h urine test was done to evaluate the rate of albuminuria. Optical coherence tomography (OCT) was conducted to detect early retinopathic changes. Subclinical atherosclerosis was assessed by measuring the carotid intima-media thickness (IMT). T1D patients showed remarkably higher concentrations of EGF, eotaxin/CCL11, MDC/CCL22, sCD40L, TGF-α, and TNF-α. Moreover, we reported statistically significant correlations between cytokines and IMT. Biomarker concentrations depend on numerous factors such as disease duration, metabolic control, and the presence of complications. Although the majority of pediatric T1D patients do not present signs of overt complications, it is indispensable to conduct the screening for angiopathies already in childhood, as its early recognition may attenuate the further progression of complications.

Cancer Stem Cell Markers-Clinical Relevance and Prognostic Value in High-Grade Serous Ovarian Cancer (HGSOC) Based on The Cancer Genome Atlas Analysis.

Cancer stem cells (CSCs) may contribute to an increased risk of recurrence in ovarian cancer (OC). Further research is needed to identify associations between CSC markers and OC patients' clinical outcomes with greater certainty. If they prove to be correct, in the future, the CSC markers can be used to help predict survival and indicate new therapeutic targets. This study aimed to determine the CSC markers at mRNA and protein levels and their association with clinical presentation, outcome, and risk of recurrence in HGSOC (High-Grade Serous Ovarian Cancer). TCGA (The Cancer Genome Atlas) database with 558 ovarian cancer tumor samples was used for the evaluation of 13 CSC markers (ALDH1A1, CD44, EPCAM, KIT, LGR5, NES, NOTCH3, POU5F1, PROM1, PTTG1, ROR1, SOX9, and THY1). Data on mRNA and protein levels assessed by microarray and mass spectrometry were retrieved from TCGA. Models to predict chemotherapy response and survival were built using multiple variables, including epidemiological data, expression levels, and machine learning methodology. ALDH1A1 and LGR5 mRNA expressions indicated a higher platinum sensitivity (p = 3.50 × 10-3; p = 0.01, respectively). POU5F1 mRNA expression marked platinum-resistant tumors (p = 9.43 × 10-3). CD44 and EPCAM mRNA expression correlated with longer overall survival (OS) (p = 0.043; p = 0.039, respectively). THY1 mRNA and protein levels were associated with worse OS (p = 0.019; p = 0.015, respectively). Disease-free survival (DFS) was positively affected by EPCAM (p = 0.004), LGR5 (p = 0.018), and CD44 (p = 0.012). In the multivariate model based on CSC marker expression, the high-risk group had 9.1 months longer median overall survival than the low-risk group (p < 0.001). ALDH1A1, CD44, EPCAM, LGR5, POU5F1, and THY1 levels in OC may be used as prognostic factors for the primary outcome and help predict the treatment response.

The diagnosis of multiple sclerosis: what has changed in diagnostic criteria?

Multiple sclerosis (MS) is a chronic, demyelinating disease affecting the central nervous system. Diagnosis of MS is based on the proof of disease dissemination in time (DIT) and dissemination in space (DIS) and excluding other disorders that can mimic multiple sclerosis in laboratory tests and clinical manifestation. Over the years the diagnostic criteria have evolved; the introduction of magnetic resonance in the McDonald's 2001 criteria was revolutionary. Since then, the criteria have been modified up to the currently used McDonald 2017. The aim of this review is to analyse the 2017 McDonald criteria, assess what has changed from the 2010 criteria, and present the impact of revised criteria on rapid and accurate diagnosis of MS. The main differences are as follows: inclusion of oligoclonal bands in cerebrospinal fluid as a DIT criterion, and symptomatic and cortical lesions in magnetic resonance imaging are counted in the determination of DIS and DIT. We present also the newest recommendations of the Polish Medical Society of Radiology and the Polish Society of Neurology and international group of North American Imaging in Multiple Sclerosis and Consortium of Multiple Sclerosis Centers, as well as future directions for further investigations. A proper diagnosis is crucial for the patient's quality of life, to give the possibility of early treatment, and to help avoid misdiagnosis and unnecessary therapy.

Regulation of human chorionic gonadotropin beta subunit expression in ovarian cancer.

PURPOSE: Expression of human chorionic gonadotropin beta subunit by cancers is extensively documented, yet regulation of the multiple genes that can code for this protein is poorly understood. The aim of the study was to examine the mechanisms regulating CGB gene expression in ovarian cancer. METHODS: Expression of CGB genes and SP1, SP3, TFAP2A transcription factor genes was evaluated by RT-qPCR. The methylation status of CGB genes promoter regions was examined by methylation-specific PCR. RESULTS: mRNA arising from multiple CGB genes was detected in both ovarian control and malignant tissues. However, expression of CGB3-9 genes was shown to be significantly higher in malignant than healthy ovarian tissues. CGB1 and CGB2 transcripts were shown to be present in 20% of ovarian cancers, but were not detected in any of the control samples. Malignant tissues were characterized by DNA demethylation of CGB promoter regions. In ovarian cancer CGB expression positively correlated with TFAP2A transcripts level and expression of TFAP2A transcription factor was significantly higher in cancer than in control tissues. In contrast SP3 expression level was significantly lower in ovarian tumours than in control ovarian tissue. CONCLUSIONS: In ovarian cancers increased expression of human chorionic gonadotropin beta subunit is associated with demethylation of CGB promoter regions. CGB3-9 expression level strongly correlates with expression of the TFAP2A transcription factor. Presence of mRNA arising from CGB1 and CGB2 genes appears to be a unique feature of a subset of ovarian cancers.

AluY-mediated germline deletion, duplication and somatic stem cell reversion in UBE2T defines a new subtype of Fanconi anemia.

Fanconi anemia (FA) is a rare inherited disorder clinically characterized by congenital malformations, progressive bone marrow failure and cancer susceptibility. At the cellular level, FA is associated with hypersensitivity to DNA-crosslinking genotoxins. Eight of 17 known FA genes assemble the FA E3 ligase complex, which catalyzes monoubiquitination of FANCD2 and is essential for replicative DNA crosslink repair. Here, we identify the first FA patient with biallelic germline mutations in the ubiquitin E2 conjugase UBE2T. Both mutations were aluY-mediated: a paternal deletion and maternal duplication of exons 2-6. These loss-of-function mutations in UBE2T induced a cellular phenotype similar to biallelic defects in early FA genes with the absence of FANCD2 monoubiquitination. The maternal duplication produced a mutant mRNA that could encode a functional protein but was degraded by nonsense-mediated mRNA decay. In the patient's hematopoietic stem cells, the maternal allele with the duplication of exons 2-6 spontaneously reverted to a wild-type allele by monoallelic recombination at the duplicated aluY repeat, thereby preventing bone marrow failure. Analysis of germline DNA of 814 normal individuals and 850 breast cancer patients for deletion or duplication of UBE2T exons 2-6 identified the deletion in only two controls, suggesting aluY-mediated recombinations within the UBE2T locus are rare and not associated with an increased breast cancer risk. Finally, a loss-of-function germline mutation in UBE2T was detected in a high-risk breast cancer patient with wild-type BRCA1/2. Cumulatively, we identified UBE2T as a bona fide FA gene (FANCT) that also may be a rare cancer susceptibility gene.

Complementation of hypersensitivity to DNA interstrand crosslinking agents demonstrates that XRCC2 is a Fanconi anaemia gene.

BACKGROUND: Fanconi anaemia (FA) is a heterogeneous inherited disorder clinically characterised by progressive bone marrow failure, congenital anomalies and a predisposition to malignancies. OBJECTIVE: Determine, based on correction of cellular phenotypes, whether XRCC2 is a FA gene. METHODS: Cells (900677A) from a previously identified patient with biallelic mutation of XRCC2, among other mutations, were genetically complemented with wild-type XRCC2. RESULTS: Wild-type XRCC2 corrects each of three phenotypes characteristic of FA cells, all related to the repair of DNA interstrand crosslinks, including increased sensitivity to mitomycin C (MMC), chromosome breakage and G2-M accumulation in the cell cycle. Further, the p.R215X mutant of XRCC2, which is harboured by the patient, is unstable. This provides an explanation for the pathogenesis of this mutant, as does the fact that 900677A cells have reduced levels of other proteins in the XRCC2-RAD51B-C-D complex. Also, FANCD2 monoubiquitination and foci formation, but not assembly of RAD51 foci, are normal in 900677A cells. Thus, XRCC2 acts late in the FA-BRCA pathway as also suggested by hypersensitivity of 900677A cells to ionising radiation. These cells also share milder sensitivities towards olaparib and formaldehyde with certain other FA cells. CONCLUSIONS: XRCC2/FANCU is a FA gene, as is another RAD51 paralog gene, RAD51C/FANCO. Notably, similar to a subset of FA genes that act downstream of FANCD2, biallelic mutation of XRCC2/FANCU has not been associated with bone marrow failure. Taken together, our results yield important insights into phenotypes related to FA and its genetic origins.

[IgG4-related disease - a case report]. / Choroba IgG4-zalezna ­ opis przypadku.

Immunoglobulin G4-related disease (IgG4-RD) is a comparatively new condition that may involve more than one organ. The lack of characteristic, pathognomonic clinical symptoms may delay the diagnosis of this disease. The diagnosis is based upon clinical manifestation, elevated serum levels of IgG4 and histopathologic examination with immunohistochemical staining to reveal infiltration of IgG4-positive plasma cells. The first line treatment is oral glucocorticoids. A CASE REPORT: 38-year-old woman with Hashimoto disease, chronic sinusitis and chronic hepatitis of unknown etiology was admitted to the Department of Endocrinology because of moderate eyelids swelling accompanied by redness for 3 years. Graves' orbitopathy and systemic vasculitis were suspected, however both were excluded (negative antibodies results: anty-TSHR, ANCA, ANA). Serologic investigation of Sjögren's syndrome was also negative. In Magnetic Resonance Imaging (MRI) of orbits there were described bilateral mild extension of lateral rectus muscles, normal signal of adipose tissue and bilateral lacrimal glands enlargement. Moreover, increased IgG4 serum levels were detected. The material derived from perinasal sinuses surgery was analyzed in histopathology examination with immunohistochemical staining, which revealed characteristic features of chronic inflammatory process and increased numbers of IgG4 - positive plasma cells (>50 in a large field of view). The diagnosis of IgG4-RD was established. Because of non-effective oral methylprednisolone therapy in the past, the patient was referred to Clinic of Rheumatology for further treatment. After the therapy with methylprednisolone and azathioprine there were observed the significant reduction of symptoms. CONCLUSIONS: Because of lack of characteristic symptoms of IgG4- RD, it should be always considered in differential diagnosis of chronic inflammatory diseases of various organs.

Impaired hydroxylation of 5-methylcytosine in myeloid cancers with mutant TET2.

TET2 is a close relative of TET1, an enzyme that converts 5-methylcytosine (5mC) to 5-hydroxymethylcytosine (5hmC) in DNA. The gene encoding TET2 resides at chromosome 4q24, in a region showing recurrent microdeletions and copy-neutral loss of heterozygosity (CN-LOH) in patients with diverse myeloid malignancies. Somatic TET2 mutations are frequently observed in myelodysplastic syndromes (MDS), myeloproliferative neoplasms (MPN), MDS/MPN overlap syndromes including chronic myelomonocytic leukaemia (CMML), acute myeloid leukaemias (AML) and secondary AML (sAML). We show here that TET2 mutations associated with myeloid malignancies compromise catalytic activity. Bone marrow samples from patients with TET2 mutations displayed uniformly low levels of 5hmC in genomic DNA compared to bone marrow samples from healthy controls. Moreover, small hairpin RNA (shRNA)-mediated depletion of Tet2 in mouse haematopoietic precursors skewed their differentiation towards monocyte/macrophage lineages in culture. There was no significant difference in DNA methylation between bone marrow samples from patients with high 5hmC versus healthy controls, but samples from patients with low 5hmC showed hypomethylation relative to controls at the majority of differentially methylated CpG sites. Our results demonstrate that Tet2 is important for normal myelopoiesis, and suggest that disruption of TET2 enzymatic activity favours myeloid tumorigenesis. Measurement of 5hmC levels in myeloid malignancies may prove valuable as a diagnostic and prognostic tool, to tailor therapies and assess responses to anticancer drugs.

hCG - related molecules and their measurement.

Measurements of human chorionic gonadotropin (hCG) synthesized by trophoblast cells is a powerful tool of pregnancy monitoring. It was showed that similarly to pregnancy also trophoblastic and nontrophoblastic malignancies produce variety of hCG molecules. In urine and serum of both pregnant women and tumors patients a fifteen various forms of hCG, such as: regular hCG, hyperglycosylated hCG and predominant hyperglycosylated hCG free ß, were identified. These forms might be useful in order to recognize between physiological and pathological pregnancies as well as cancers. Even the presence of these different hormone variants is well documented the commercially available biochemical tests detecting hCG failed to identified and distinguish among these forms. Especially hard is to identify glycan chains linked to heterodimer. Thus, a detailed analysis of hCG-related molecules produced during physiological and pathological condition, together with a new tests development are needed.

PARP inhibitors: review of mechanisms of action and BRCA1/2 mutation targeting.

Poly(ADP-ribose) polymerases have shown true promise in early clinical studies due to reported activity in BRCA-associated cancers. PARP inhibitors may represent a potentially important new class of chemotherapeutic agents directed at targeting cancers with defective DNA-damage repair. In order to widen the prospective patient population that would benefit from PARP inhibitors, predictive biomarkers based on a clear understanding of the mechanism of action are required. In addition, a more sophisticated understanding of the toxicity profile is required if PARP inhibitors are to be employed in the curative, rather than the palliative, setting. PARP inhibitors have successfully moved into clinical practice in the past few years, with approval granted from the Food and Drug Administration (FDA) and European Medicines Agency (EMA) within the past two years. The United States FDA approval of olaparib applies to fourth-line treatment in germline BRCA-mutant ovarian cancer, and European EMA approval of olaparib for maintenance therapy in both germline and somatic BRCA-mutant platinum-sensitive ovarian cancer. This review covers the current understanding of PARP, its inhibition, and the basis of the excitement surrounding these new agents. It also evaluates future approaches and directions required to achieve full understanding of the intricate interplay of these agents at the cellular level.

Minotaur is critical for primary piRNA biogenesis.

Piwi proteins and their associated small RNAs are essential for fertility in animals. In part, this is due to their roles in guarding germ cell genomes against the activity of mobile genetic elements. piRNA populations direct Piwi proteins to silence transposon targets and, as such, form a molecular code that discriminates transposons from endogenous genes. Information ultimately carried by piRNAs is encoded within genomic loci, termed piRNA clusters. These give rise to long, single-stranded, primary transcripts that are processed into piRNAs. Despite the biological importance of this pathway, neither the characteristics that define a locus as a source of piRNAs nor the mechanisms that catalyze primary piRNA biogenesis are well understood. We searched an EMS-mutant collection annotated for fertility phenotypes for genes involved in the piRNA pathway. Twenty-seven homozygous sterile strains showed transposon-silencing defects. One of these, which strongly impacted primary piRNA biogenesis, harbored a causal mutation in CG5508, a member of the Drosophila glycerol-3-phosphate O-acetyltransferase (GPAT) family. These enzymes catalyze the first acylation step on the path to the production of phosphatidic acid (PA). Though this pointed strongly to a function for phospholipid signaling in the piRNA pathway, a mutant form of CG5508, which lacks the GPAT active site, still functions in piRNA biogenesis. We have named this new biogenesis factor Minotaur.

Type, density, and presentation of grafted adhesion peptides on polysaccharide-based hydrogels control preosteoblast behavior and differentiation.

In this work, cell-responsive polysaccharide hydrogels were prepared by a simple procedure based on the sequential bioconjugation and cross-linking of the polysaccharide backbone with bioactive peptides and poly(ethylene glycol)-bis(thiol) (PEG-(SH)2), respectively. Using thiol-ene reactions, we successfully functionalized hyaluronic acid (HA) and carboxymethylcellulose (CMC) with short and long peptides (5-mer and 15-mer derivatives, respectively) derived from adhesive proteins of bone extracellular matrix. The resulting HA-peptide and CMC-peptide conjugates with varying degrees of substitution were then carefully characterized by (1)H NMR spectroscopy to precisely control the peptide density into the hydrogels cross-linked with PEG-(SH)2. Preosteoblast seeded on the hydrogels with controlled identical stiffness spread in a manner that was strongly dependent on ligand density. Surprisingly, increasing the density of the adhesive peptide anchors did not result in a plateau of initial cell spreading but rather in a bell-shaped cell response that varies with the nature of both polysaccharide backbone and functional peptide. Placing the cells under optimal conditions for cell/hydrogel interaction, we showed that in HA hydrogels, the polysaccharide moiety is not solely a passive scaffold that presents the active peptides but is an active player in cell microenvironment to control and sustain cell activity.

Evaluation of survivin splice variants in pituitary tumors.

PURPOSE: Survivin is an apoptosis inhibitor, expressed in almost all types of human malignancies, but rarely in differentiated normal tissues. Recently, survivin gene splice variants with different anti-apoptotic activities have been reported. The current study was undertaken to examine the expression of survivin and its splice variants ∆Ex3 and 2ß in pituitary tumors, and to correlate the amount of particular transcripts with clinical staging in pituitary adenomas. Quantitative detection of survivin and its splice variants ∆Ex3 and 2ß transcripts in non-cancerous pituitary tissues (n = 12) and different types of pituitary tumor (n = 50). METHODS: Samples were collected from 50 pituitary tumors including 26 non-functional tumors, 21 GH-secreting tumors, 2 PRL-secreting tumors and 1 ACTH-secreting tumor. 12 normal pituitary glands received after autopsy served as a control of the study. 29 thyroid cancers tissues were used as a positive control. The RT-qPCR with TaqMan hydrolysis probes were used to determine the expression of analyzed splice variants of survivin. RESULTS: The obtained data showed that both survivin and its splice variants were expressed in different types of pituitary adenoma as well as in normal pituitary tissue. However, the level of its expression was similar in all studied cases. Patient age negatively correlated with tumor invasiveness. Moreover, our study showed a tendency for negative correlation between patient age and tumor diameter. CONCLUSIONS: No significant differences between survivin and its splice variants ∆Ex3 and 2ß expression in pituitary tumors and in normal pituitary glands as well as in invasive and in non-invasive tumors were found, suggesting that survivin does not play a significant role in pituitary tumorigenesis.

Ovarian cancer and normal fallopian tube high WFDC2 expression does not correlate with HE4 serum level.

OBJECTIVES: Recent evidence suggests that epithelial ovarian cancer (EOC) does not derive from ovarian surface epithelium but from the tissues of Mullerian origin, particularly from the fallopian tube. HE4, a protein of Mullerian origin, seems to be promising marker for EOC detection and treatment monitoring. This study was designed to compare the expression of WFDC2 gene, encoding HE4 protein, in normal tissue of the ovary fallopian tube and EOC. The correlation between WFDC2 expression in cancer tissue and serum level of HE4 was additionally measured. MATERIAL AND METHODS: Tumor specimens were obtained from EOC patients during primary surgery before chemotherapy Samples of normal ovaries and fallopian tubes were collected from healthy patients operated for other reasons. Total RNA was isolated from the tissues and relative WFDC2 expression was evaluated by Real Time RT-qPCR. HE4 serum level in cancer patients was measured using COBAS System. RESULTS: EOC samples were distinguished by much higher WFDC2 expression in comparison to normal ovaries (p = 0.000016). Transcriptional activity of WFDC2 in EOC specimens and in normal fallopian tubes was comparable (p = 1.00). Additionally, lack of correlation between WFDC2 expression in cancer tissue and serum level of HE4 protein in ovarian cancer patients was observed (p = 0.3). CONCLUSIONS: High expression of WFDC2 was demonstrated for both, EOC and fallopian tube, as opposed to its low expression observed in normal ovaries suggesting that EOC is derived from fallopian tube rather than ovary Elevated HE4 serum concentration in EOC patients is not correlated with higher gene expression in cancer tissue.

Visfatin and TGF-Β1 in primary biliary cirrhosis and two other common liver diseases.

UNLABELLED: The aim of this study is to investigate plasma concentration of visfatin and transforming growth factor Β1 (TGF-Β1) in three groups of patients: primary biliary cirrhosis (PBC), non-alcoholic fatty liver disease (NAFLD) and toxic cirrhosis (TC). We qualified the patients into the study and assigned them to the appropriate group according to clinical examination, laboratory tests and ultrasound imaging technic (US). We showed that plasma concentrations of visfatin in PBC, NAFLD and TC group were respectively 1.41 ± 1.76 ng/mL, 1.22 ± 1.08 ng/mL and 0.70 ± 1.22 ng/mL. Plasma concentration of visfatin was significantly lower in TC group than in others both (p ± 0.017). The differences of visfatin concentration between NAFLD and TC group were not statistically significant. The values of TGF-Β1 in PBC, NAFLD and TC group were respectively 21031 ± 7822 pg/mL, 21588 ± 12639 pg/mL, and 9678 ± 4757 pg/mL. The statistical analysis showed that the value of cirrhotic group was significantly (p ±0.017) lower compared to both others groups. The difference between PBC and NAFLD was insignificant. IN CONCLUSION: Despite the PBC and NAFLD are the diseases of different pathogenesis and origin, plasma concentration of visfatin and TGF-Β1 were similar in these both groups but significantly lower in TC probably due to decreased activity as well as number of cells producing these cytokines in the cirrhotic liver.

Mutations in the spliceosome machinery, a novel and ubiquitous pathway in leukemogenesis.

Myelodysplastic syndromes (MDSs) are chronic and often progressive myeloid neoplasms associated with remarkable heterogeneity in the histomorphology and clinical course. Various somatic mutations are involved in the pathogenesis of MDS. Recently, mutations in a gene encoding a spliceosomal protein, SF3B1, were discovered in a distinct form of MDS with ring sideroblasts. Whole exome sequencing of 15 patients with myeloid neoplasms was performed, and somatic mutations in spliceosomal genes were identified. Sanger sequencing of 310 patients was performed to assess phenotype/genotype associations. To determine the functional effect of spliceosomal mutations, we evaluated pre-mRNA splicing profiles by RNA deep sequencing. We identified additional somatic mutations in spliceosomal genes, including SF3B1, U2AF1, and SRSF2. These mutations alter pre-mRNA splicing patterns. SF3B1 mutations are prevalent in low-risk MDS with ring sideroblasts, whereas U2AF1 and SRSF2 mutations are frequent in chronic myelomonocytic leukemia and advanced forms of MDS. SF3B1 mutations are associated with a favorable prognosis, whereas U2AF1 and SRSF2 mutations are predictive for shorter survival. Mutations affecting spliceosomal genes that result in defective splicing are a new leukemogenic pathway. Spliceosomal genes are probably tumor suppressors, and their mutations may constitute diagnostic biomarkers that could potentially serve as therapeutic targets.

SF3B1 haploinsufficiency leads to formation of ring sideroblasts in myelodysplastic syndromes.

Whole exome/genome sequencing has been fundamental in the identification of somatic mutations in the spliceosome machinery in myelodysplastic syndromes (MDSs) and other hematologic disorders. SF3B1, splicing factor 3b subunit 1 is mutated in 60%-80% of refractory anemia with ring sideroblasts (RARS) and RARS associated with thrombocytosis (RARS-T), 2 distinct subtypes of MDS and MDS/myeloproliferative neoplasms (MDSs/MPNs). An idiosyncratic feature of RARS/RARS-T is the presence of abnormal sideroblasts characterized by iron overload in the mitochondria, called RS. Based on the high frequency of mutations of SF3B1 in RARS/RARS-T, we investigated the consequences of SF3B1 alterations. Ultrastructurally, SF3B1 mutants showed altered iron distribution characterized by coarse iron deposits compared with wild-type RARS patients by transmission electron microscopy. SF3B1 knockdown experiments in K562 cells resulted in down-regulation of U2-type intron-splicing by RT-PCR. RNA-sequencing analysis of SF3B1 mutants showed differentially used genes relevant in MDS pathogenesis, such as ASXL1, CBL, EZH, and RUNX families. A SF3B pharmacologic inhibitor, meayamycin, induced the formation of RS in healthy BM cells. Further, BM aspirates of Sf3b1 heterozygous knockout mice showed RS by Prussian blue. In conclusion, we report the first experimental evidence of the association between SF3B1 and RS phenotype. Our data suggest that SF3B1 haploinsufficiency leads to RS formation.