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Aicardi-Goutières syndrome (AGS) is an inflammatory disorder caused by mutations in any of six genes (TREX1, RNASEH2A, RNASEH2B, RNASEH2C, SAMHD1, and ADAR). The disease is severe and effective treatments are urgently needed. We investigated the status of interferon-related biomarkers in patients with AGS with a view to future use in diagnosis and clinical trials. In this case-control study, samples were collected prospectively from patients with mutation-proven AGS. The expression of six interferon-stimulated genes (ISGs) was measured by quantitative PCR, and the median fold change, when compared with the median of healthy controls, was used to create an interferon score for each patient. Scores higher than the mean of controls plus two SD (>2·466) were designated as positive. Additionally, we collated historical data for interferon activity, measured with a viral cytopathic assay, in CSF and serum from mutation-positive patients with AGS. We also undertook neutralisation assays of interferon activity in serum, and looked for the presence of autoantibodies against a panel of interferon proteins. 74 (90%) of 82 patients had a positive interferon score (median 12·90, IQR 6·14–20·41) compared with two (7%) of 29 controls (median 0·93, IQR 0·57–1·30). Of the eight patients with a negative interferon score, seven had mutations in RNASEH2B (seven [27%] of all 26 patients with mutations in this gene). Repeat sampling in 16 patients was consistent for the presence or absence of an interferon signature on 39 of 41 occasions. Interferon activity (tested in 147 patients) was negatively correlated with age (CSF, r=−0·604; serum, r=−0·289), and was higher in CSF than in serum in 104 of 136 paired samples. Neutralisation assays suggested that measurable antiviral activity was related to interferon α production. We did not record significantly increased concentrations of autoantibodies to interferon subtypes in patients with AGS, or an association between the presence of autoantibodies and interferon score or serum interferon activity. AGS is consistently associated with an interferon signature, which is apparently sustained over time and can thus be used to differentiate patients with AGS from controls. If future studies show that interferon status is a reactive biomarker, the measurement of an interferon score might prove useful in the assessment of treatment efficacy in clinical trials. European Union's Seventh Framework Programme; European Research Council.

Background Mesenchymal stem cells (MSCs)-based and MSCs-derived extracellular vesicle (EV) therapies, have garnered significant attention as potential treatments for severe Coronavirus disease 19 (Covid-19), leading to evaluation in numerous clinical trials. This interest stems from the observed ability of MSCs, and their EVs, to mitigate the hyper-inflammatory state that characterizes severe cases of the disease. However, despite the promising preclinical and early clinical results, the precise mechanisms of action remain unclear, hindering therapy optimization. Methods This study investigated the response of Wharton’s jelly-derived mesenchymal stem cells (WJ-MSCs) to a diverse panel of sera collected from multiple hospitalized Covid-19 patients, aiming to recapitulate in vitro the spectrum of inflammatory conditions MSCs encounter in vivo. Results Exposure to Covid-19 serum activated WJ-MSCs, increasing proliferation and RNA/protein synthesis. Transcriptomic analysis revealed an early and significant downregulation of the inflammation-related long non-coding RNAs (lncRNAs) NEAT1 and MALAT1 . This downregulation of NEAT1 and MALAT1 , triggered by Covid-19 serum, suggests a potential mechanism by which WJ-MSCs may limit excessive inflammation. Importantly, reducing MALAT1 (and to a lesser extent NEAT1 ) expression in WJ-MSCs enhanced the therapeutic potential of MSC-derived EVs. This suggests that targeting pro-inflammatory lncRNAs in parental cells could be a promising therapeutic strategy for managing Covid-19 and other inflammatory lung diseases.

Congenital central hypoventilation syndrome (CCHS or Ondine's curse; OMIM 209880) is a life-threatening disorder involving an impaired ventilatory response to hypercarbia and hypoxemia. This core phenotype is associated with lower-penetrance anomalies of the autonomic nervous system (ANS) including Hirschsprung disease and tumors of neural-crest derivatives such as ganglioneuromas and neuroblastomas. In mice, the development of ANS reflex circuits is dependent on the paired-like homeobox gene Phox2b . Thus, we regarded its human ortholog, PHOX2B , as a candidate gene in CCHS. We found heterozygous de novo mutations in PHOX2B in 18 of 29 individuals with CCHS. Most mutations consisted of 5–9 alanine expansions within a 20-residue polyalanine tract probably resulting from non-homologous recombination. We show that PHOX2B is expressed in both the central and the peripheral ANS during human embryonic development. Our data support an essential role of PHOX2B in the normal patterning of the autonomous ventilation system and, more generally, of the ANS in humans.

Osteogenesis Imperfecta (OI) is a rare genetic disease characterized by bone fragility, with a wide range in the severity of clinical manifestations. The majority of cases are due to mutations in COL1A1 or COL1A2 , which encode type I collagen. There is no cure for OI, and real concerns exist for current therapeutic approaches, mainly antiresorptive drugs, regarding their effectiveness and security. Safer and effective therapeutic approaches are demanded. Cell therapy with mesenchymal stem cells (MSCs), osteoprogenitors capable of secreting type I collagen, has been tested to treat pediatric OI with encouraging outcomes. Another therapeutic approach currently under clinical development focuses on the inhibition of TGF-β pathway, based on the excessive TGF-β signaling found in the skeleton of severe OI mice models, and the fact that TGF-β neutralizing antibody treatment rescued bone phenotypes in those OI murine models. An increased serum expression of TGF-β superfamily members has been described for a number of bone pathologies, but still it has not been addressed in OI patients. To delve into this unexplored question, in the present study we investigated serum TGF-β signalling pathway in two OI pediatric patients who participated in TERCELOI, a phase I clinical trial based on reiterative infusions of MSCs. We examined not only the expression and bioactivity of circulating TGF-β pathway in TERCELOI patients, but also the effects that MSCs therapy could elicit. Strikingly, basal serum from the most severe patient showed an enhanced expression of several TGF-β superfamily members and increased TGF-β bioactivity, which were modulated after MSCs therapy.

Tatton-Brown-Rahman syndrome (TBRS; OMIM 615879), also known as the DNMT3A-overgrowth syndrome, is an overgrowth intellectual disability syndrome first described in 2014 with a report of 13 individuals with constitutive heterozygous DNMT3A variants. Here we have undertaken a detailed clinical study of 55 individuals with de novo DNMT3A variants, including the 13 previously reported individuals. An intellectual disability and overgrowth were reported in >80% of individuals with TBRS and were designated major clinical associations. Additional frequent clinical associations (reported in 20-80% individuals) included an evolving facial appearance with low-set, heavy, horizontal eyebrows and prominent upper central incisors; joint hypermobility (74%); obesity (weight ³2SD, 67%); hypotonia (54%); behavioural/psychiatric issues (most frequently autistic spectrum disorder, 51%); kyphoscoliosis (33%) and afebrile seizures (22%). One individual was diagnosed with acute myeloid leukaemia in teenage years. Based upon the results from this study, we present our current management for individuals with TBRS

Background Osteogenesis imperfecta (OI) is a rare genetic disease characterized by bone fragility, with a wide range in the severity of clinical manifestations. The majority of cases are due to mutations in the COL1A1 or COL1A2 genes, which encode type I collagen. Mesenchymal stem cells (MSCs), as the progenitors of the osteoblasts, the main type I collagen secreting cell type in the bone, have been proposed and tested as an innovative therapy for OI with promising but transient outcomes. Methods To overcome the short‐term effect of MSCs therapy, we performed a phase I clinical trial based on reiterative infusions of histocompatible MSCs, administered in a 2.5‐year period, in two pediatric patients affected by severe and moderate OI. The aim of this study was to assess the safety and effectiveness of this cell therapy in nonimmunosuppressed OI patients. The host response to MSCs was studied by analyzing the sera from OI patients, collected before, during, and after the cell therapy. Results We first demonstrated that the sequential administration of MSCs was safe and improved the bone parameters and quality of life of OI patients along the cell treatment plus 2‐year follow‐up period. Moreover, the study of the mechanism of action indicated that MSCs therapy elicited a pro‐osteogenic paracrine response in patients, especially noticeable in the patient affected by severe OI. Conclusions Our results demonstrate the feasibility and potential of reiterative MSCs infusion for two pediatric OI and highlight the paracrine response shown by patients as a consequence of MSCs treatment. TERCELOI clinical trial addresses fundamental issues concerning the feasibility, security and potential of 5 MSCs infusions in two non immunosuppressed Osteogenesis Imperfecta pediatric patients. This trial allowed us to elucidate the mechanism of action of MSCs therapy, characterized by a pro‐osteogenic paracrine response. For that, we studied the protein and miRNA levels in sera from patients (collected before, along and after the cell treatment) besides unraveling the transcriptomic alterations due to those sera presence, and demonstrating their functional capabilities.

Background Deficient nucleotide excision repair (NER) activity causes a variety of autosomal recessive diseases including xeroderma pigmentosum (XP) a disorder which pre-disposes to skin cancer, and the severe multisystem condition known as Cockayne syndrome (CS). In view of the clinical overlap between NER-related disorders, as well as the existence of multiple phenotypes and the numerous genes involved, we developed a new diagnostic approach based on the enrichment of 16 NER-related genes by multiplex amplification coupled with next-generation sequencing (NGS). Methods Our test cohort consisted of 11 DNA samples, all with known mutations and/or non pathogenic SNPs in two of the tested genes. We then used the same technique to analyse samples from a prospective cohort of 40 patients. Multiplex amplification and sequencing were performed using AmpliSeq protocol on the Ion Torrent PGM (Life Technologies). Results We identified causative mutations in 17 out of the 40 patients (43 %). Four patients showed biallelic mutations in the ERCC6(CSB) gene, five in the ERCC8(CSA) gene: most of them had classical CS features but some had very mild and incomplete phenotypes. A small cohort of 4 unrelated classic XP patients from the Basque country (Northern Spain) revealed a common splicing mutation in POLH (XP-variant), demonstrating a new founder effect in this population. Interestingly, our results also found ERCC2(XPD), ERCC3(XPB) or ERCC5(XPG) mutations in two cases of UV-sensitive syndrome and in two cases with mixed XP/CS phenotypes. Conclusions Our study confirms that NGS is an efficient technique for the analysis of NER-related disorders on a molecular level. It is particularly useful for phenotypes with combined features or unusually mild symptoms. Targeted NGS used in conjunction with DNA repair functional tests and precise clinical evaluation permits rapid and cost-effective diagnosis in patients with NER-defects.

Brachydactyly (BD) refers to the shortening of the hands, feet or both. There are different types of BD; among them, type E (BDE) is a rare type that can present as an isolated feature or as part of more complex syndromes, such as: pseudohypopthyroidism (PHP), hypertension with BD or Bilginturan BD (HTNB), BD with mental retardation (BDMR) or BDE with short stature, PTHLH type. Each syndrome has characteristic patterns of skeletal involvement. However, brachydactyly is not a constant feature and shows a high degree of phenotypic variability. In addition, there are other syndromes that can be misdiagnosed as brachydactyly type E, some of which will also be discussed. The objective of this review is to describe some of the syndromes in which BDE is present, focusing on clinical, biochemical and genetic characteristics as features of differential diagnoses, with the aim of establishing an algorithm for their differential diagnosis. As in our experience many of these patients are recruited at Endocrinology and/or Pediatric Endocrinology Services due to their short stature, we have focused the algorithm in those steps that could mainly help these professionals.

Background Silver-Russell Syndrome (SRS) is a rare growth-related genetic disorder mainly characterized by prenatal and postnatal growth failure. Although molecular causes are not clear in all cases, the most common mechanisms involved in SRS are loss of methylation on chromosome 11p15 (≈50%) and maternal uniparental disomy for chromosome 7 (upd(7)mat) (≈10%). Case presentation We present a girl with clinical suspicion of SRS (intrauterine and postnatal growth retardation, prominent forehead, triangular face, mild psychomotor delay, transient neonatal hypoglycemia, mild hypotonia and single umbilical artery). Methylation and copy number variations at chromosomes 11 and 7 were studied by methylation-specific multiplex ligation-dependent probe amplification and as no alterations were found, molecular karyotyping was performed. A deletion at 5p15.33p15.2 was identified (arr[GRCh37] 5p15.33p15.2(25942–11644643)× 1), similar to those found in patients with Cri-du-chat Syndrome (CdCS). CdCS is a genetic disease resulting from a deletion of variable size occurring on the short arm of chromosome 5 (5p-), whose main feature is a high-pitched mewing cry in infancy, accompanied by multiple congenital anomalies, intellectual disability, microcephaly and facial dysmorphism. Conclusions The absence of some CdCS features in the current patient could be due to the fact that in her case the critical regions responsible do not lie within the identified deletion. In fact, a literature review revealed a high degree of concordance between the clinical manifestations of the two syndromes.

Nazneen Rahman, Katrina Tatton-Brown and colleagues identify de novo mutations in the DNA methyltransferase gene DNMT3A as the cause of a new overgrowth syndrome. Shared features of this syndrome include a distinctive facial appearance, intellectual disability and greater height. Overgrowth disorders are a heterogeneous group of conditions characterized by increased growth parameters and other variable clinical features such as intellectual disability and facial dysmorphism 1 . To identify new causes of human overgrowth, we performed exome sequencing in ten proband-parent trios and detected two de novo DNMT3A mutations. We identified 11 additional de novo mutations by sequencing DNMT3A in a further 142 individuals with overgrowth. The mutations alter residues in functional DNMT3A domains, and protein modeling suggests that they interfere with domain-domain interactions and histone binding. Similar mutations were not present in 1,000 UK population controls (13/152 cases versus 0/1,000 controls; P < 0.0001). Mutation carriers had a distinctive facial appearance, intellectual disability and greater height. DNMT3A encodes a DNA methyltransferase essential for establishing methylation during embryogenesis and is commonly somatically mutated in acute myeloid leukemia 2 , 3 , 4 . Thus, DNMT3A joins an emerging group of epigenetic DNA- and histone-modifying genes associated with both developmental growth disorders and hematological malignancies 5 .