Recurrence and Familial Inheritance of Intronic NIPBL Pathogenic Variant Associated With Mild CdLS

Splicing pathogenic variants account for a notable fraction of NIPBL alterations underlying Cornelia de Lange syndrome but are likely underrepresented, due to overlooking of non-canonical intronic variants by traditional and contemporary sequencing methods. We describe five subjects, belonging to three families, displaying a mild Cornelia de Lange syndrome phenotype who carry the NIPBL pathogenic variant c.5329–15A>G, affecting the IVS27 branch site, yet reported in a single case. By RNA analysis we evidenced two alternative transcripts: the exon 28 in frame skipped transcript, described in the published case and an out-of-frame transcript retaining 14 nucleotides of IVS27 3′end. Even if both aberrant transcripts are at negligible levels, their presence justifies the CdLS phenotype shared by our patients consisting of borderline-mild cognitive impairment and slight but typical facial dysmorphisms. Transmission of the pathogenic variant from pauci-symptomatic mother to her siblings emphasizes the need of molecular diagnosis extended to deep intronic regions in patients with subtle but recognizable CdLS phenotype

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

Teaching to teach with a LMS: the experience at University of Perugia

[EN] A Learning Management System (LMS) is nowadays a pivotal element in the education environment of a modern university. However, though it generally has a beneficial and positive impact on the education, a part of the teachers is sometimes reluctant to adopt a LMS because of the perceived usage difficulty. Therefore, it is clear that a key step in order to spread the use of a LMS is to teach to the teachers how to use it and which benefits their teaching activities can gain. In this paper, we report and analyze the experience we had at University of Perugia. An e-learning course has been released to the (approximately) 1000 teachers of the university with the aim of introducing them to the basic tools provided by the LMS. Importantly, the course has been created and delivered by means of UniStudium, i.e., the Moodle-based LMS deployed in our university. This allowed us to collect interesting quantitative and qualitative data that have been elaborated and analyzed. The analysis shows that the activities carried out reached a prominent percentage of teachers, by also providing us important suggestions and hints to guide our future activities in this direction.http://ocs.editorial.upv.es/index.php/HEAD/HEAD18Filomia, M.; Santucic, V.; Vinti, G.; De Santis, GMP.; Falcinelli, F.; Frenguelli, G.; Lorenzi, C.... (2018). Teaching to teach with a LMS: the experience at University of Perugia. Editorial Universitat Politècnica de València. 1439-1447. https://doi.org/10.4995/HEAD18.2018.8221OCS1439144

DNA methylation episignature testing improves molecular diagnosis of Mendelian chromatinopathies

Purpose: Chromatinopathies include more than 50 disorders caused by disease-causing variants of various components of chromatin structure and function. Many of these disorders exhibit unique genome-wide DNA methylation profiles, known as episignatures. In this study, the methylation profile of a large cohort of individuals with chromatinopathies was analyzed for episignature detection. Methods: DNA methylation data was generated on extracted blood samples from 129 affected individuals with the Illumina Infinium EPIC arrays and analyzed using an established bioinformatic pipeline. Results: The DNA methylation profiles matched and confirmed the sequence findings in both the discovery and validation cohorts. Twenty-five affected individuals carrying a variant of uncertain significance, did not show a methylation profile matching any of the known episignatures. Three additional variant of uncertain significance cases with an identified KDM6A variant were re-classified as likely pathogenic (n = 2) or re-assigned as Wolf-Hirschhorn syndrome (n = 1). Thirty of the 33 Next Generation Sequencing negative cases did not match a defined episignature while three matched Kabuki syndrome, Rubinstein-Taybi syndrome and BAFopathy respectively. Conclusion: With the expanding clinical utility of the EpiSign assay, DNA methylation analysis should be considered part of the testing cascade for individuals presenting with clinical features of Mendelian chromatinopathy disorders

Clinical and molecular characterization of patients affected by Beckwith-Wiedemann spectrum conceived through assisted reproduction techniques

The prevalence of Beckwith-Wiedemann spectrum (BWSp) is tenfold increased in children conceived through assisted reproductive techniques (ART). More than 90% of ART-BWSp patients reported so far display imprinting center 2 loss-of-methylations (IC2-LoM), versus 50% of naturally conceived BWSp patients. We describe a cohort of 74 ART-BWSp patients comparing their features with a cohort of naturally conceived BWSp patients, with the ART-BWSp patients previously described in literature, and with the general population of children born from ART. We found that the distribution of UPD(11)pat was not significantly different in ART and naturally conceived patients. We observed 68.9% of IC2-LoM and 16.2% of mosaic UPD(11)pat in our ART cohort, that strongly differ from the figure reported in other cohorts so far. Since UPD(11)pat likely results from post-fertilization recombination events, our findings allows to hypothesize that more complex molecular mechanisms, besides methylation disturbances, may underlie BWSp increased risk in ART pregnancies. Moreover, comparing the clinical features of ART and non-ART BWSp patients, we found that ART-BWSp patients might have a milder phenotype. Finally, our data show a progressive increase in the prevalence of BWSp over time, paralleling that of ART usage in the last decades

MIR137 is the key gene mediator of the syndromic obesity phenotype of patients with 1p21.3 microdeletions.

BACKGROUND: Deletions in the long arm of chromosome 1 have been described in patients with a phenotype consisting primarily of obesity, intellectual disability and autism-spectrum disorder. The minimal region of overlap comprises two genes: DPYD and MIR137. CASE PRESENTATION: We describe a 10-year-old boy with syndromic obesity who carries a novel 1p21.3 deletion overlapping the critical region with the MIR137 gene only. CONCLUSIONS: This study suggests that MIR137 is the mediator of the obesity phenotype of patients carrying 1p21.3 microdeletions

Rubinstein-Taybi Syndrome: spectrum of CREBBP mutations in Italian patients

BACKGROUND: Rubinstein-Taybi Syndrome (RSTS, MIM 180849) is a rare congenital disorder characterized by mental and growth retardation, broad and duplicated distal phalanges of thumbs and halluces, facial dysmorphisms and increased risk of tumors. RSTS is caused by chromosomal rearrangements and point mutations in one copy of the CREB-binding protein gene (CREBBP or CBP) in 16p13.3. To date mutations in CREBBP have been reported in 56.6% of RSTS patients and an average figure of 10% has ascribed to deletions. METHODS: Our study is based on the mutation analysis of CREBBP in 31 Italian RSTS patients using segregation analysis of intragenic microsatellites, BAC FISH and direct sequencing of PCR and RT-PCR fragments. RESULTS: We identified a total of five deletions, two of the entire gene and three, all in a mosaic condition, involving either the 5' or the 3' region. By direct sequencing a total of 14 de novo mutations were identified: 10 truncating (5 frameshift and 5 nonsense), one splice site, and three novel missense mutations. Two of the latter affect the HAT domain, while one maps within the conserved nuclear receptor binding of (aa 1–170) and will probably destroy a Nuclear Localization Signal. Identification of the p.Asn1978Ser in the healthy mother of a patient also carrying a de novo frameshift mutation, questions the pathogenetic significance of the missense change reported as recurrent mutation. Thirteen additional polymorphisms, three as of yet unreported, were also detected. CONCLUSION: A high detection rate (61.3%) of mutations is confirmed by this Italian study which also attests one of the highest microdeletion rate (16%) documented so far

CUX1-related neurodevelopmental disorder: deep insights into phenotype-genotype spectrum and underlying pathology

Heterozygous, pathogenic CUX1 variants are associated with global developmental delay or intellectual disability. This study delineates the clinical presentation in an extended cohort and investigates the molecular mechanism underlying the disorder in a Cux1+/− mouse model. Through international collaboration, we assembled the phenotypic and molecular information for 34 individuals (23 unpublished individuals). We analyze brain CUX1 expression and susceptibility to epilepsy in Cux1+/− mice. We describe 34 individuals, from which 30 were unrelated, with 26 different null and four missense variants. The leading symptoms were mild to moderate delayed speech and motor development and borderline to moderate intellectual disability. Additional symptoms were muscular hypotonia, seizures, joint laxity, and abnormalities of the forehead. In Cux1+/− mice, we found delayed growth, histologically normal brains, and increased susceptibility to seizures. In Cux1+/− brains, the expression of Cux1 transcripts was half of WT animals. Expression of CUX1 proteins was reduced, although in early postnatal animals significantly more than in adults. In summary, disease-causing CUX1 variants result in a non-syndromic phenotype of developmental delay and intellectual disability. In some individuals, this phenotype ameliorates with age, resulting in a clinical catch-up and normal IQ in adulthood. The post-transcriptional balance of CUX1 expression in the heterozygous brain at late developmental stages appears important for this favorable clinical course.CAG was supported by the Eunice Kennedy Shriver National Institute Of Child Health & Human Development of the National Institutes of Health under Award Number P50 HD103525. This work was funded by PID2020-112831GB-I00 AEI /10.13039/501100011033 (MN). SS was supported by a grant from the NIH/NINDS (K23NS119666). SWS is supported by the Hospital for Sick Children Foundation, Autism Speaks, and the University of Toronto McLaughlin Center. EM-G was supported by a grant from MICIU FPU18/06240. EVS. was supported by a grant from the NIH (EY025718). CRF was supported by the fund to support clinical research careers in the Region of Southern Denmark (Region Syddanmarks pulje for kliniske forskerkarriereforløb).Peer reviewe