Thrombocytopenia with Absent Radii (TAR) syndrome is a rare congenital disorder caused by compound inheritance of a hypomorphic non-coding variant and a null allele of RBM8A. In most patients, the null allele corresponds to a recurrent 1q21.1 microdeletion encompassing RBM8A and adjacent genes, whereas cases due to RBM8A null point pathogenic variants are rarer so that the clinical spectrum associated with non-deletional RBM8A defects remains still poorly characterized. We report three patients with TAR syndrome from two unrelated families carrying compound heterozygosity for hypomorphic and null RBM8A variants. Clinical, hematological and orthopedic data were collected. A narrative review of previously published TAR patients with RBM8A null point variants in trans with hypomorphic alleles was performed. All patients displayed a complete TAR phenotype, including thrombocytopenia and bilateral radial agenesis with thumb preservation. In one family, a novel frameshift RBM8A variant (c.78_91del14; p.His26Glnfs*22) was identified, expanding the mutational spectrum of the gene. Review of published cases confirmed that compound heterozygosity for RBM8A null variants is sufficient to cause the full TAR phenotype. Notably, one pediatric patient showed severe knee abnormalities, including hypoplastic patella and trochlear dysplasia, documented by X-ray and MRI. Our findings confirm that RBM8A haploinsufficiency alone is sufficient to determine the complete TAR phenotype and highlight under-recognized orthopedic manifestations, particularly involving the knee. Comprehensive molecular and orthopedic evaluation should be considered in patients with non-deletional RBM8A-related TAR syndrome.

Sickle cell disease (SCD) is a global health problem causing premature deaths and preventable severe chronic complications. A priority goal to improve outcomes both in the short and long term is the screening for early diagnosis and access to specialized care. In Italy, as in other countries, no systematic national screening program is available. A regional pilot project was developed with the aim to screen 1000 children at risk of SCD in Italy. Primary care paediatricians received point-of-care tests (POCTs) to detect abnormal haemoglobin (Hb) to be offered to children regularly followed at their own clinics. Children positive to the POCT were referred to the regional paediatric specialized centre for diagnosis confirmation and follow up. Among 1000 at risk children screened, 85 (8,5

Anecdotal Literature regarding hereditary spherocytosis, a rare hemolytic anemia, points to an early cerebrovascular involvement that would imply early strict patients’ monitoring and management. However, this issue is under-investigated. Clinical history regarding cerebrovascular events in the young ( < 55 years) was investigated in a referral Center for hereditary spherocytosis (190 patients; mean-age 23.5 ± 17.4 years; range 1–77; 93 females). By means of 3T-MR scanner, intracranial artery stenoses, aneurysms, brain infarctions, vascular-like white matter lesions and signs of sinus thrombosis were searched in 69 adult patients (mean-age 36.5 ± 16.3 years, range 14–76, 38 females) and in 56 healthy subjects (mean-age 34 ± 10.8 years, range 17–66, 36 females). Laboratory and clinical data, including splenectomy, were collated. Among patients no cerebrovascular events occurred before the age of 55, while among their first-degree relatives, sudden death of unknown cause occurred in three subjects, two of them not affected by hereditary spherocytosis. In the MR-subgroup, moya-moya or even intracranial stenoses were not observed, while intracranial aneurysm (11.6

Transfer of vaccine antibodies (Ab) from donors to recipients after transfusion of packed red blood cells (RBC) is supposed, thus affecting the recipients’ response to vaccinations. In this prospective study, SARS-CoV-2 IgG level in donors’ serum and RBC supernatant samples was assessed. Among 346 subjects, 280 were referred for hyperimmune plasma donation and 30 for whole blood donations. All units underwent pre-storage filtration, and residual plasma volume was 18±18 mL. The mean total IgG and IgM levels were 171.43 ± 48.79 and 11.43 ± 10.69 mg/dL respectively, with significant reduction after plasma depletion and filtration (IgG 5.86 ± 5.2 and IgM 1.43 ± 3.78, p < 0.05). Anti-COVID-19 Ab were identified in serum of 28/30 (93.5%) blood donors but were absent in all blood units. The mean value of anti-SARS-CoV-2 IgG level in donors’ serum samples and in RBC units was 8.80 S/C (range 0.01–23.4) and 0.11 (range 0.01–0.37) S/C, respectively ( p <0.05). This study shows deplasmation and leukodepletion of RBC units ensured removal of IgG content and no red blood cell unit was reactive for anti-COVID-19 antibodies even from donors with high serum titre. These findings demonstrate that deplasmated and leukodepleted RBCs are not to be considered blood products containing substantial amounts of immune globulin, and differently from other blood derived-products containing Ab, transfusions with deplasmated and leukodepleted RBCs do not require delayed vaccinations and a revision of current recommendations is requested.

The purpose of this best practice paper is to review the current recommendations for the identification and prenatal diagnosis of hemoglobinopathies. Methods: The management committee of SITE selected and gathered a multidisciplinary team in order to formulate recommendations based on the available scientific evidence integrated with the opinions of experts, with the purpose of supporting clinicians. Results: We provide recommendations for first level tests (complete blood count, hemoglobin separation and iron balance), second level tests (molecular diagnosis) and prenatal diagnosis. Five Italian experts in hemoglobinopathies were consulted regarding the orientation of prenatal diagnosis, and for each indication, the degree of agreement among the experts has been specified. Conclusions: Best practice recommendations are the final outcome of this translational research and allow transfer to daily clinical practice.

Measles, mumps and rubella (MMR) still determine significant morbidity and mortality, although a highly effective vaccine is available. Postponing the MMR vaccination until 6 months after the last red blood cell (RBC) transfusion is recommended, but this delay is incompatible with chronic transfusions. The present study aimed at investigating the impact of blood transfusions on the immunogenicity of the MMR vaccine. In this observational study, a group of 45 transfusion- dependent (TD) patients was compared to 24 non-transfusion-dependent (NTD) patients. Immunity to measles was achieved in 35 (78%) TD and 21 (88%) NTD subjects (p = 0.7), to mumps in 36 (80%) TD and 21 (88%) NTD subjects (p = 0.99), and to rubella in 40 (89%) TD and 23 (96%) NTD subjects (p = 0.99). No significant difference was observed in the number of non-immune individuals or those with doubtful protection between the two groups (p > 0.05). The mean IgG value, assayed in 50 pre-storage leukoreduced RBC units, was 0.075 ± 0.064 mg/mL, ten times lower than the level assumed in blood units and considered detrimental to the immune response in TD patients. This work shows a favorable response to MMR vaccination in TD and NTDT patients and paves the way for further larger studies assessing the impact of chronic transfusions on vaccine response.

A young man with polycythemia, reduced growth rate, persistent hypoglycemia, and mitochondrial defects first appearing at birth was found to have a synonymous homozygous mutation in VHL (c.222C -> A) that created a cryptic splice site leading to the production of a truncated VHL protein. Mutations in VHL, which encodes von Hippel-Lindau tumor suppressor (VHL), are associated with divergent diseases. We describe a patient with marked erythrocytosis and prominent mitochondrial alterations associated with a severe germline VHL deficiency due to homozygosity for a novel synonymous mutation (c.222C -> A, p.V74V). The condition is characterized by early systemic onset and differs from Chuvash polycythemia (c.598C -> T) in that it is associated with a strongly reduced growth rate, persistent hypoglycemia, and limited exercise capacity. We report changes in gene expression that reprogram carbohydrate and lipid metabolism, impair muscle mitochondrial respiratory function, and uncouple oxygen consumption from ATP production. Moreover, we identified unusual intermitochondrial connecting ducts. Our findings add unexpected information on the importance of the VHL-hypoxia-inducible factor (HIF) axis to human phenotypes. (Funded by Associazione Italiana Ricerca sul Cancro and others.)

Most reports of post-transplant erythrocytosis have involved kidney recipients and, so far, there have been no large studies of onset of erythrocytosis after orthotopic liver transplantation (OLT) in children. We present a long-term survey of pediatric liver recipients, evaluating prevalence, outcome and the main potential causes of erythrocytosis, including a comprehensive mutational analysis of commonly related genes (mutations of HBB and HBA, JAK2, EPOR, VHL, EPAS1 and EGLN1). Between 2000 and 2015, 90 pediatric OLT recipients were observed for a median period of 8.7 years (range 1–20.4 [IQR 4.9–13.6] years). Five percent of the study population (4 males and 1 female) developed erythrocytosis at 8.5 years post OLT (range 4.1–14.9 [IQR 4.7–14.7]) at a median age of 16.6 years (range 8.2–18.8 [IQR 11.7–17.7]). Erythrocytosis-free survival after OLT was 98.6% at 5 years, 95% at 10 years, and 85% at 15 years, with an incidence rate of 6/1000 person-years. No cardiovascular events or thrombosis were reported. No germinal mutation could be clearly related to the development of erythrocytosis. One patient, with high erythropoietin levels and acquired multiple bilateral renal cysts, developed clinical hyper-viscosity symptoms, and was treated with serial phlebotomies. In conclusion, this prospective longitudinal study showed that erythrocytosis is a rare complication occurring several years after OLT, typically during adolescence. Erythrocytosis was non-progressive and manageable. Its pathogenesis is still not completely understood, although male gender, pubertal age, and renal cysts probably play a role.

Hb variants are structurally abnormal haemoglobins which can originate a wide range of phenotypes from clinically silent conditions to very severe disorders. In many cases, diagnosis is very difficult due to the instability of Hb mutants or the occurrence of misleading symptoms, such as cyanosis or hypoxia. Here we report the case of a young female with undiagnosed chronic haemolytic anaemia and low oxygen saturation in the absence of respiratory distress. High performance liquid chromatography showed the occurrence of an abnormal peak in the HbA2 region, which disappeared few days after blood sampling. Genetic analysis of both a genes revealed the -alpha 3.7 deletion in heterozygous state and a novel mutation c.130 T > C leading to the substitution of Phenylalanine at codon 43 with Leucine in the alpha 1 gene. This substitution originated a new Hb variant, named Hb Vanvitelli, with a molecular mass of 15,092.2 +/- 0.4 Da. Biochemical and laboratory tests described a hyper unstable Hb variant with altered oxygen affinity that was clinically significant only when co-inherited with genetic defects affecting the alpha 2 locus. This case highlights the genetic complexity and diagnostic pitfalls of Hb variants, defined "experiments of nature" which can generate severe clinical conditions.

Background: Autosomal dominant neurohypophyseal diabetes insipidus (adNDI) is caused by arginine vasopressin (AVP) deficiency resulting from mutations in the AVP-NPII gene encoding the AVP preprohormone. Aim: To describe the clinical and molecular features of Italian unrelated families with central diabetes insipidus. Patients and methods: We analyzed AVP-NPII gene in 13 families in whom diabetes insipidus appeared to be segregating. Results: Twenty-two patients were found to carry a pathogenic AVP-NPII gene mutation. Two novel c.173 G>C (p.Cys58Ser) and c.215 C>A (p.Ala72Glu) missense mutations and additional eight different mutations previously described were identified; nine were missense and one non-sense mutation. Most mutations (eight out of ten) occurred in the region encoding for the NPII moiety; two mutations were detected in exon 1. No mutations were found in exon 3. Median age of onset was 32.5 months with a variability within the same mutation (3 to 360 months). No clear genotype-phenotype correlation has been observed, except for the c.55 G>A (p.Ala19Thr) mutation, which led to a later onset of disease (median age 120 months). Brain magnetic resonance imaging (MRI) revealed the absence of posterior pituitary hyperintensity in 8 out of 15 subjects, hypointense signal in 4 and normal signal in 2. Follow-up MRI showed the disappearance of the posterior pituitary hyperintensity after 6 years in one case. Conclusion: adNDI is a progressive disease with a variable age of onset. Molecular diagnosis and counseling should be provided to avoid unnecessary investigations and to ensure an early and adequate treatment.

The management of iron overload in thalassemia has changed dramatically since the implementation of magnetic resonance imaging, which allows detection of preclinical iron overload and prevention of clinical complications. This study evaluated the effect of deferasirox (DFX), the newest once-daily oral chelator, on cardiac function, iron overload and cardiovascular events over a longer follow up in a "real world" setting. Longitudinal changes in cardiac magnetic resonance T2*, cardiac function parameters and cardiovascular clinical events were assessed in a cohort of 98 TM patients exposed to DFX for a mean of 6.9 years (range 1.8-11.6 years). No cardiac death or incident heart failure occurred. Cardiac T2* significantly increased (+2.6 ± 11.9 msec; P = 0.035) in the whole population, with a significantly greater increase (+11.6 ± 15.5 msec, P = 0.019) in patients with cardiac iron overload (T2* <20 ms). A significant improvement in left-ventricular ejection fraction (LVEF) (from 50.6 ± 6 to 60.2 ± 5; P = 0.001) was observed in 11 (84.6%) out of 13 patients who normalized cardiac function (LVEF >56%). Arrhythmias were the most frequent cardiac adverse event noted but none led to DFX discontinuation. Our data indicate that DFX is effective in maintaining cardiac iron level in the normal range and in improving cardiac iron overload. No heart failure or cardiac death was reported over this longer observation up to 12 years. For the first time, a DFX-induced improvement in LVEF was observed in a subgroup of patients with abnormal cardiac function at baseline, a preliminary observation which deserves further evaluation.

A 20-year-old male affected by transfusion-dependent β-thalassemia (β-thal), was prescribed intensive chelation therapy with deferoxamine (DFO) and deferiprone (DFP) because of severe hepatic and cardiac iron overload and β-blocker and warfarin to manage a previous event of atrial fibrillation (AFib) and heart failure. After a few months, he developed critical liver failure, renal tubulopathy and severe electrolyte imbalance. Laboratory and instrumental evaluations were performed to carry out differential diagnosis of acute liver failure and an exclusion diagnosis of drug induced liver injury (DILI) was made. The cholestatic pattern suggested warfarin as the main causative agent and polypharmacy, liver iron overload and heart failure as aggravating factors. Warfarin is a drug commonly prescribed in thalassemia patients who often need polypharmacy for the management of anemia- and iron-related complications. Strict monitoring and multidisciplinary approaches are mandatory to avoid preventable mortality in this fragile population.

Hypochromic microcytic anemias are due to altered erythroblastic iron availability reducing the hemoglobin (Hb) content of red cells.1 In addition to the most common causes of hereditary microcytic anemias (thalassemias, thalassaemic hemoglobinopathies and sideroblastic anemias), several atypical forms have been identified.1 Such disorders are associated with inherited changes of genes (TMPRSS6, transferrin, DMT1, STEAP3, ALAS2, GLRX5, and ceruplasmin) involved in iron metabolism.1 However, the scarce number of cases identified has not yet allowed their precise molecular and clinical characterization. DMT1 is an integral membrane protein acting as a proton-coupled divalent metal transporter. It is expressed at the apical border of duodenal enterocytes where it allows the uptake of dietary/nonheme iron. In other tissues (especially in erythroid precursors), DMT1 mediates the transfer of iron, internalized by transferrin, from the endosomes to cytoplasm.2 Recently, it has been suggested that DMT1 allows the metal import into the mitochondria in addition to the previous described so-called “kiss-and-run” fusion mechanism by which endosomes and lysosomes directly transfer iron to these organelles.3 Pivotal studies performed in mice and rats identified a DMT1 missense mutation as responsible for a microcytic phenotype. Subsequently, DMT1 mutations have been described in six patients with hypochromic microcytic anemia. All subjects but one presented liver iron overload.4 Importantly, except for two cases, no DMT1 immunoblotting analyses were performed. Here, we report the identification of a patient with microcytic hypocromic anemia due to two novel DMT1 alterations. The patient presented transfusion-dependent anemia until she was 3 years old (Supporting Information Table S1). Then, recombinant erythropoietin (rEpo) treatment was started at 15 μg/week, avoiding any further blood transfusions (Figure 1A). The rEpo dose was increased over-time and, at present, it is 150 μg/week administered subcutaneously. The child is healthy, her growth curves are constantly between 50th-75th centiles and satisfactory Hb levels have been maintained. Liver iron concentration (LIC) was calculated from liver T2* measured by magnetic resonance imaging at the age of 6, 10, and 11 years with no liver and/or cardiac iron overload detected (Figure 1B). (A) Values of hemoglobin (Hb, g/dL) in relation to recombinant erytropoietin (rEPO) treatment. (B) Proband's clinical and laboratory data during rEpo treatment. (C) Genomic sequence of DMT1 exon 15 of the proband identifying the R477W mutation; (D) Genomic sequence of DMT1 exon 4 intron 4 junction of the proband identifying ivs4 + 1 G/C change; (E) Pedigree of the family with 2 new DMT1 mutations; (F) Schematic representation of DMT1 exon 4 skipping in the proband Exons and exon-intron boundaries sequencing of DMT1 gene allowed the characterization of our patient as a compound heterozygote for two new DMT1 mutations. We found a C > T transition at nucleotide 1429 of exon 15 (R477W) (Figure 1C) and a G > C substitution at position +1 bp of the splice-donor site within intron 4 (ivs4 + 1 G/C) (Figure 1D). The R477W was inherited from proband's mother, while ivs4 + 1 G/C was of paternal inheritance (Figure 1E). The mutation R477W was not found in single nucleotide polymorphism (SNP) databases (htpp://www.ncbi.nlm.nih.gov/SNP/) nor detected by sequencing the corresponding exon in 50 healthy subjects. A different change on R477 residue (R477Q) has been detected in a patient with BRAFV600E-mutant metastatic melanoma. Particularly, this was one of the four DMT1 mutations acquired upon treatment of melanoma patients with Vemurafenib, a Raf kinase inhibitor. The study suggests that mutations in DMT1 could be associated to the drug resistance.5 The amino acid substitution R477W found in our patient is predicted to be damaging by Polyphen multicriteria software (http://www.bork.embl-heidelberg.de/PolyPhen/). To investigate whether ivs4 + 1 G/C mutation might affect RNA maturation by inactivating the splice-donor site, DMT1 mRNAs (from PBLs) was analysed. cDNA amplification/sequencing of the DMT1 mRNA region between exons 2 and 8 produced in controls a single transcript (522 bps), while 2 transcripts were obtained from the proband cDNA (Supporting Information Figure S1A). The improperly spliced RNA lacks exon 4 but maintains the correct reading frame (Figure 1F). The putatively translated protein should lack 42 amino acids from residues 62 to 103 that might result into uncorrected protein insertion/activity into plasma membrane (Supporting Information Figure S1B). The proband exon 4-including DMT1 transcript was reduced to 50–60% of the DMT1 mRNA level of a control subject (not shown). To evaluate the effect of mutations on DMT1 protein content, we prepared cell extracts from the EBV-transformed lymphoblasts of the proband and her relatives and analysed them by gel-electrophoresis/immunoblotting. A 30–40% reduction of the protein was evidenced in the proband and her father compared to I-2 (Supporting Information Figure S2A). No signals associated to a smaller DMT1 isoform were evidenced suggesting that mRNA lacking exon 4 was not efficiently translated or, alternatively, that the mutated protein was unstable (Supporting Information Figure S2B). So far, the major clinical features of the six previously described patients include hypocromic and microcytic anemia, high serum iron and transferrin saturation, increased serum soluble transferrin receptor, with normal or slightly increased serum ferritin. Liver iron overload was reported in all but one of the described cases. Recent studies have shown a mitochondrial membrane localization for DMT1, suggesting a role in iron uptake by mitochondria, where the first steps of heme synthesis occur. Mice lacking hepatic DMT1 (Dmt1liv/liv mice) that do not show measurable changes in liver iron suggest that DMT1 is dispensable for the overall hepatic iron economy.6 In particular, DMT1 mutations do not alter liver NTBI (non transferrin-bound iron) uptake and faintly reduce TBI incorporation. We suggest that liver iron accumulation might not be directly due to DMT1 mutation, and perhaps be just a consequence of transfusions or of anemic-state per-se. It is also possible that recombinant Epo treatment may prevent potential liver damage. In conclusion, although very rare, DMT1 deficiency must be taken into consideration in the differential diagnosis of neonatal microcytic hypochromic anemia. Indeed, an early identification and an immediate rEpo treatment improve the management of the disease and may avoid transfusions. The study received approval from the Institutional Review Board of University of Campania, Italy. The authors declare no competing financial interests. Additional Supporting Information may be found online in the supporting information tab for this article. Supporting Information 1 Supporting Information 2 Supporting Information 3 Supporting Information 4 Supporting Information 5 Please note: The publisher is not responsible for the content or functionality of any supporting information supplied by the authors. Any queries (other than missing content) should be directed to the corresponding author for the article.

Background: Iron overload syndromes include a wide range of diseases frequently associated with increased morbidity and mortality. Several organs are affected in patients with iron overload including liver, heart, joints, endocrine glands, and pancreas. Moreover, severe bone and hemopoietic tissue alterations are observed. Because of the role of bone marrow mesenchymal stromal cells (BM-MSCs) in bone turnover and hematopoiesis, iron effects on primary BM-MSCs cultures were evaluated.Methods: Primary human BM-MSCs cultures were prepared and the effects of iron on their proliferation and differentiation were characterized by biochemical analyses and functional approaches.Results: Addition of iron to the culture medium strongly increased BM-MSCs proliferation and induced their accelerated S phase entry. Iron enters BM-MSCs through both transferrin-dependent and transferrin-independent mechanisms, inducing the accumulation of cyclins E and A, the decrease of p27(Kip1), and the activation of MAPK pathway. Conversely, neither apoptotic signs nor up-regulation of reactive oxygen species were observed. Iron inhibited both differentiation of BM-MSCs into osteoblasts and in vitro matrix calcification. These effects result from the merging of inhibitory activities on BM-MSCs osteoblastic commitment and on the ordered matrix calcification process.Conclusions: We demonstrated that BM-MSCs are a target of iron overload. Iron accelerates BM-MSCs proliferation and affects BM-MSCs osteoblastic commitment, hampering matrix calcification.General Significance: Our study reports, for the first time, that iron, at concentration found in overloaded patient sera, stimulates the growth of BM-MSCs, the BM multipotent stromal cell component. Moreover, iron modulates the physiological differentiation of these cells, affecting bone turnover and remodeling. (C) 2016 Elsevier B.V. All rights reserved.

OBJECTIVE:Idiopathic early-onset central diabetes insipidus (CDI) might be due to mutations of arginine vasopressin-neurophysin II (AVP-NPII (AVP)) or wolframin (WFS1) genes.DESIGN AND METHODS:Sequencing of AVP and WFS1 genes was performed in nine children with CDI, aged between 9 and 68 months, and negative family history for polyuria and polydipsia.RESULTS:Two patients carried a mutation in the AVP gene: a heterozygous G-to-T transition at nucleotide position 322 of exon 2 (c.322G>T) resulting in a stop codon at position 108 (p.Glu108X), and a novel deletion from nucleotide 52 to 54 (c.52_54delTCC) producing a deletion of a serine at position 18 (p.Ser18del) of the AVP pre-prohormone signal peptide. A third patient carried two heterozygous mutations in the WFS1 gene localized on different alleles. The first change was A-to-G transition at nucleotide 997 in exon 8 (c.997A>G), resulting in a valine residue at position 333 in place of isoleucine (p.Ile333Val). The second novel mutation was a 3 bp insertion in exon 8, c.2392_2393insACG causing the addition of an aspartate residue at position 797 and the maintenance of the correct open reading frame (p. Asp797_Val798insAsp). While similar WFS1 protein levels were detected in fibroblasts from healthy subjects and from the patient and his parents, a major sensitivity to staurosporine-induced apoptosis was observed in the patient fibroblasts as well as in patients with Wolfram syndrome.CONCLUSIONS:Early-onset CDI is associated with de novo mutations of the AVP gene and with hereditary WFS1 gene changes. These findings have valuable implications for management and genetic counseling.

Diagnosis within RASopathies still represents a challenge. Nevertheless, many efforts have been made by clinicians to identify specific clinical features which might help in differentiating one disorder from another. Here, we describe a child initially diagnosed with Neurofibromatosis-Noonan syndrome. The follow-up of the proband, the clinical evaluation of his father together with a gene-by-gene testing approach led us to the proper diagnosis.

Hypoxia-inducible factor 2α (HIF-2α) plays a pivotal role in the balancing of oxygen requirements throughout the body. The protein is a transcription factor that modulates the expression of a wide array of genes and, in turn, controls several key processes including energy metabolism, erythropoiesis and angiogenesis. We describe here the identification of two cases of familial erythrocytosis associated with heterozygous HIF2A missense mutations, namely Ile533Val and Gly537Arg. Ile533Val is a novel mutation and represents the genetic HIF2A change nearest to Pro-531, the primary hydroxyl acceptor residue, so far identified. The Gly537Arg missense mutation has already been described in familial erythrocytosis. However, our patient is the only described case of a de novo HIF2A mutation associated with the development of congenital polycythemia. Functional in vivo studies, based on exogenous expression of hybrid HIF-2α transcription factors, indicated that these genetic alterations lead to the stabilization of HIF-2α protein. All the identified polycythemic subjects with HIF2A mutations show serum erythropoietin in the normal range, independently of the hematocrit values and phlebotomy frequency. The erythroid precursors obtained from the peripheral blood of patients showed an altered phenotype, including an increased rate of growth and a modified expression of some HIF-2α target genes. These results suggest the novel proposal that polycythemia observed in subjects with HIF2A mutations might also be due to primary changes in hematopoietic cells and not only secondary to increased erythropoietin levels.

BACKGROUNDMaturity onset diabetes of young (MODY) type 5 is a form of non-insulin-dependent diabetes mellitus associated with renal cysts. It is an autosomal dominant disorder caused by mutations in the gene encoding hepatocyte nuclear factor-1β (HNF-1β).METHODSWe performed molecular screening of HNF-1β in a 13-year-old patient and his affected father, and analyzed polycystic kidney disease 2 (PKD2) gene and suppressor of cytokine signaling 3 (SOCS3) expression in lymphoblastoid cell lines and lymphocytes from both patients.RESULTSWe found a novel HNF-1β frameshift mutation (c.C1304del) that results in a truncated protein (p.I434IfsX1). The genetic change is localized in the transactivated protein domain.CONCLUSIONSWe demonstrated that this novel HNF-1β mutation strongly influences the expression of both PKD2, responsible for the formation of the renal cysts, and SOCS3, which is associated with early diabetes onset.