Low-grade parental gonosomal mosaicism in CHD2 siblings with Smith-Magenis-like syndrome.

Loss-of-function CHD2 (chromodomain helicase DNA-binding protein 2) mutations are associated with a spectrum of neurodevelopmental disorders often including early-onset generalized seizures, photosensitivity, and epileptic encephalopathies. Patients show psychomotor delay/intellectual disability (ID), autistic features, and behavior disorders, such as aggression and impulsivity. Most reported cases are sporadic with description of germline mosaicism only in two families. We detect the first case of parental gonosomal CHD2 mosaicism disclosed by two brothers showing mild ID, born to healthy parents. The eldest brother has a history of drug-controlled generalized tonic-clonic seizures and displays sleep disorder and aggressive behavior suggestive of Smith-Magenis syndrome (SMS). Analysis of brothers' DNAs by next-generation sequencing (NGS) custom gene panel for pediatric epilepsy and/or ID disclosed in both the same pathogenic CHD2 variant. Additional NGS experiment on genomic DNA from parents' peripheral blood and from buccal swab raised the suspicion of low-grade gonosomal mosaicism in the unaffected mother subsequently confirmed by digital polymerase chain reaction (dPCR). This report underlines as worthwhile CHD2 screening in individuals presenting ID/developmental delay, with/without epilepsy, and behavior and sleep disorders suggestive of SMS. Detecting a CHD2 variant should prime testing probands' parents by NGS coupled to dPCR on different tissues to exclude/confirm gonosomal mosaicism and define the recurrence risk.

Modeling RTT Syndrome by iPSC-Derived Neurons from Male and Female Patients with Heterogeneously Severe Hot-Spot MECP2 Variants.

Rett syndrome caused by MECP2 variants is characterized by a heterogenous clinical spectrum accounted for in 60% of cases by hot-spot variants. Focusing on the most frequent variants, we generated in vitro iPSC-neurons from the blood of RTT girls with p.Arg133Cys and p.Arg255*, associated to mild and severe phenotype, respectively, and of an RTT male harboring the close to p.Arg255*, p.Gly252Argfs*7 variant. Truncated MeCP2 proteins were revealed by Western blot and immunofluorescence analysis. We compared the mutant versus control neurons at 42 days for morphological parameters and at 120 days for electrophysiology recordings, including girls' isogenic clones. A precocious reduced morphological complexity was evident in neurons with truncating variants, while in p.Arg133Cys neurons any significant differences were observed in comparison with the isogenic wild-type clones. Reduced nuclear size and branch number show up as the most robust biomarkers. Patch clamp recordings on mature neurons allowed the assessment of cell biophysical properties, V-gated currents, and spiking pattern in the mutant and control cells. Immature spiking, altered cell capacitance, and membrane resistance of RTT neurons, were particularly pronounced in the Arg255* and Gly252Argfs*7 mutants. The overall results indicate that the specific markers of in vitro cellular phenotype mirror the clinical severity and may be amenable to drug testing for translational purposes.

Histone Deacetylase Inhibitors Ameliorate Morphological Defects and Hypoexcitability of iPSC-Neurons from Rubinstein-Taybi Patients.

Rubinstein-Taybi syndrome (RSTS) is a rare neurodevelopmental disorder caused by mutations in CREBBP or EP300 genes encoding CBP/p300 lysine acetyltransferases. We investigated the efficacy of the histone deacetylase inhibitor (HDACi) Trichostatin A (TSA) in ameliorating morphological abnormalities of iPSC-derived young neurons from P149 and P34 CREBBP-mutated patients and hypoexcitability of mature neurons from P149. Neural progenitors from both patients' iPSC lines were cultured one week with TSA 20 nM and, only P149, for 6 weeks with TSA 0.2 nM, in parallel to neural progenitors from controls. Immunofluorescence of MAP2/TUJ1 positive cells using the Skeletonize Image J plugin evidenced that TSA partially rescued reduced nuclear area, and decreased branch length and abnormal end points number of both 45 days patients' neurons, but did not influence the diminished percentage of their neurons with respect to controls. Patch clamp recordings of TSA-treated post-mitotic P149 neurons showed complete/partial rescue of sodium/potassium currents and significant enhancement of neuron excitability compared to untreated replicas. Correction of abnormalities of P149 young neurons was also affected by valproic acid 1 mM for 72 h, with some variation, with respect to TSA, on the morphological parameter. These findings hold promise for development of an epigenetic therapy to attenuate RSTS patients cognitive impairment.

Temperature-dependent regulation of the Escherichia coli lpxT gene.

The Lipid A moiety of the lipopolysaccharide can be covalently modified during its transport to the outer membrane by different enzymes, among which the LpxT inner membrane protein. LpxT transfers a phosphate group from the undecaprenyl pyrophosphate to the Lipid A, a modification affecting the stability of the outer membrane and its recognition by the host immune system in Enterobacteria. We previously found that the expression of the Pseudomonas aeruginosa lpxT gene, encoding LpxT, is induced in response to a temperature upshift and we proposed that an RNA thermometer was responsible for such regulation. Here we show that the Escherichia coli lpxT orthologous gene is down-regulated upon a temperature upshift and investigated the mechanism of this regulation. We found that the LpxT protein stability is not affected by the temperature change. Conversely, the lpxT mRNA levels strongly decrease upon a shift from 28 to 42 °C. The lack of MicA sRNA, which was previously implicated in lpxT regulation, does not affect lpxT thermal regulation. We identified the lpxTp promoter and demonstrated that lpxTp has temperature-sensitive activity depending on its peculiar -10 region. Moreover, we found that RNase E-dependent degradation of the lpxT mRNA is also modulated by temperature causing a strong destabilization of the lpxT mRNA at 42 °C. In vitro data argue against the involvement of factors differentially expressed at 28 and 42 °C in the temperature-dependent modulation of lpxT mRNA stability.

Adolescent nonsuicidal self-injury: the effects of personality traits, family relationships and maltreatment on the presence and severity of behaviours.

Personality traits, family environment and maltreatment episodes are often associated with nonsuicidal self-injury (NSSI); however, research on these associations has shown mixed results. The aim of the present study was to clarify the effects of these factors on the presence and the severity of NSSI among a sample of Italian students who attended secondary schools (N = 267, mean age = 17.03 SD = 0.866). The results showed that personality traits, family environment and maltreatment differently predicted the presence and the severity of NSSI. Self-injurers were more impulsive and aggressive than non-self-injurers and reported poorer relationship quality with their mothers and more sexual and physical abuse episodes than non-self-injurers. Conversely, the frequency of NSSI behaviours was predicted by the presence of less impulsiveness, more anxiety and aggressiveness, poorer relationship quality with both parents and a lower degree of identification with the father. Finally, more frequent self-injurers also reported more sexual abuses and neglect episodes than less frequent self-injurers.