MYT1L mutations cause intellectual disability and variable obesity by dysregulating gene expression and development of the neuroendocrine hypothalamus

Deletions at chromosome 2p25.3 are associated with a syndrome consisting of intellectual disability and obesity. The smallest region of overlap for deletions at 2p25.3 contains PXDN and MYT1L. MYT1L is expressed only within the brain in humans. We hypothesized that single nucleotide variants (SNVs) in MYT1L would cause a phenotype resembling deletion at 2p25.3. To examine this we sought MYT1L SNVs in exome sequencing data from 4, 296 parent-child trios. Further variants were identified through a genematcher-facilitated collaboration. We report 9 patients with MYT1L SNVs (4 loss of function and 5 missense). The phenotype of SNV carriers overlapped with that of 2p25.3 deletion carriers. To identify the transcriptomic consequences of MYT1L loss of function we used CRISPR-Cas9 to create a knockout cell line. Gene Ontology analysis in knockout cells demonstrated altered expression of genes that regulate gene expression and that are localized to the nucleus. These differentially expressed genes were enriched for OMIM disease ontology terms “mental retardation”. To study the developmental effects of MYT1L loss of function we created a zebrafish knockdown using morpholinos. Knockdown zebrafish manifested loss of oxytocin expression in the preoptic neuroendocrine area. This study demonstrates that MYT1L variants are associated with syndromic obesity in humans. The mechanism is related to dysregulated expression of neurodevelopmental genes and altered development of the neuroendocrine hypothalamus

High Flow Nasal Cannula (HFNC) versus Continuous Positive Airway Pressure (CPAP) for primary respiratory support in preterm infants: a meta-analysis

Introduction : L’efficacité et la tolérance de l’oxygénothérapie aux lunettes haut débit (OLHD) chez le nouveau-né prématuré ont été démontrées en relais post extubation, mais les données concernant l’OLHD en primo-thérapie dans le syndrome de détresse respiratoire du nouveau-né prématuré sont insuffisantes et discordantes. Nous avons mené une revue systématique et méta-analyse d’études contrôlées randomisées pour évaluer l’efficacité et la tolérance de l’OLHD comparée à la ventilation spontanée en pression expiratoire positive (CPAP) en primothérapie du syndrome de détresse respiratoire du nouveau-né prématuré dans les 24 premières heures de vie, ainsi qu’une analyse en sous-groupe par âge gestationnel et étudier l’impact des paramètres cliniques. Méthode : Les études contrôlées randomisées ont été recherchées dans les bases de données PubMed, Cochrane Library, Embase, et CINHAL jusqu’au 25 aout 2020, avec comme critère de jugement principal l’échec du traitement. Nous avons calculé les risques relatifs en intention de traiter et effectué des méta-analyses en utilisant un modèle à effet aléatoire (modèle de DerSimonian-Laird). L’hétérogénéité a été évaluée à partir d’une analyse des funnel-plots et du test d’hétérogénéité de I2. Résultats : 10 études ont été incluses, pour un total de 1830 patients. L’âge gestationnel de naissance des patients inclus allait de 28 à 37 semaines de gestation. Les débits d’OLHD allaient de 2-5L/min à 5-8 L/min. Les modes de CPAP utilisés étaient sur ventilateur, à bulle ou les deux, pour des pressions allant de 2 à 8 mmHg. Le traitement par surfactant était autorisé dans 7 études sur 10. Notre méta-analyse montre une multiplication de 1.42 du risque d’échec de traitement avec l’OLHD comparée à la CPAP (95CI 1.07 to 1.79, I2=25.4%) sans différence en fonction des groupes d’âge gestationnel. Les méta-régressions n’ont pas démontré d’impact des paramètres cliniques sur les résultats: l’âge gestationnel, le poids de naissance, le débit de l’OLHD, le mode de CPAP ou l’utilisation de surfactant. Conclusion : Nous proposons que l’OLHD ne soit pas utilisée à la place de la CPAP en primo-thérapie dans le syndrome de détresse respiratoire du nouveau-né prématuré, et ce quel que soit l’âge gestationnel de naissance

Systematic review of high-flow nasal cannula versus continuous positive airway pressure for primary support in preterm infants

International audienceIntroduction We conducted a meta-analysis of trials that compared efficacy and safety of high-flow nasal cannula (HFNC) with continuous positive airway pressure (CPAP) as primary respiratory support in preterm infants and a study of the impact of clinical relevant parameters. Methods Databases were searched for randomised controlled trials comparing HFNC with CPAP as primary respiratory support in preterm infants. Treatment failure was considered as primary outcome and adverse events as secondary outcomes. We calculated risk ratios (RRs) in intention-to-treat analysis and random-effects meta-analyses of risks were conducted. Results We included 10 studies for a total of 1830 patients. Meta-analysis demonstrated an RR of treatment failure multiplied by 1.34 using HFNC compared with CPAP (RR=1.34, 95% CI 1.01 to 1.68, I 2 =16.2%). Secondary outcome meta-analysis showed no difference in intubation rates (RR=0.90, 95% CI 0.66 to 1.15) and a lower rate of nasal trauma using HFNC compared with CPAP (RR=0.48, 95% CI 0.31 to 0.65, I²=0.0%). Meta-regressions did not show any influence of gestational age and weight at birth, HFNC flow rate, type of CPAP generator or use of surfactant. Conclusions Despite a higher risk of treatment failure, considering no difference in intubation rates and a lower rate of nasal trauma using HFNC compared with CPAP, we suggest that HFNC should be used as primary respiratory support in preterm infants

Characterization of RAGE and CK2 Expressions in Human Fetal Membranes

At the feto-maternal interface, fetal membranes (FM) play a crucial role throughout pregnancy. FM rupture at term implicates different sterile inflammation mechanisms including pathways activated by the transmembrane glycoprotein receptor for advanced glycation end-products (RAGE) belonging to the immunoglobulin superfamily. As the protein kinase CK2 is also implicated in the inflammation process, we aimed to characterize the expressions of RAGE and the protein kinase CK2 as a candidate regulator of RAGE expression. The amnion and choriodecidua were collected from FM explants and/or primary amniotic epithelial cells throughout pregnancy and at term in spontaneous labor (TIL) or term without labor (TNL). The mRNA and protein expressions of RAGE and the CK2α, CK2α′, and CK2β subunits were investigated using reverse transcription quantitative polymerase chain reaction and Western blot assays. Their cellular localizations were determined with microscopic analyses, and the CK2 activity level was measured. RAGE and the CK2α, CK2α′, and CK2β subunits were expressed in both FM layers throughout pregnancy. At term, RAGE was overexpressed in the amnion from the TNL samples, whereas the CK2 subunits were expressed at the same level in the different groups (amnion/choriodecidua/amniocytes, TIL/TNL), without modification of the CK2 activity level and immunolocalization. This work paves the way for future experiments regarding the regulation of RAGE expression by CK2 phosphorylation

Hypothalamic peptide expression in zebrafish knockdown for <i>MYT1L</i> orthologues.

<p>(A)Whole mount in situ hybridization demonstrating that <i>MYT1L</i> orthologs <i>myt1la</i> and <i>myt1lb</i> are expressed throughout the zebrafish central nervous system. T = telencephalon, te = tectum, hy = hypothalamus, h = hindbrain. (B)Whole mount in situ hybridization demonstrating loss of <i>myt1la</i> expression in <i>arnt2</i> mutant zebrafish, top panel shows control fish and bottom panel <i>arnt2</i> mutant fish. The embryos are heavily over-stained to show the low-level expression of <i>myt1la</i> in the ventral diencephalon. The arrow indicates the region of the neuroendocrine preoptic area where oxytocin expressing neurons are located. (C)Whole mount in situ hybridization demonstrating that knockdown of <i>myt1la</i> and <i>myt1lb</i>, alone or in combination, results in loss of oxytocin expression in the neuroendocrine preoptic area. Arrows indicate neuroendocrine preoptic area. (D)Bar chart quantifying loss of oxytocin expression in neuroendocrine preoptic area. WISH for oxytocin was quantified as follows: ~30 cells = wild type expression, 5–15 cells = reduced, 1–4 = highly reduced, 0 = no expression (E)Whole mount in situ hybridization demonstrating that knockdown of <i>myt1la/b</i> results in loss of arginine vasopressin expression in the neuroendocrine preoptic region (indicated by arrow) but not the ventral hypothalamus (indicated by arrowhead). (F) Bar chart quantifying loss of arginine vasopression expression in <i>myt1la/b</i> morphants. WISH for arginine vasopressin was quantified as follows: ~30 cells = wild type expression, 5–15 cells = reduced, 1–4 = highly reduced, 0 = no expression.</p

Clinical characterization of <i>MYT1L</i> variant carriers.

<p>The heatmap depicts the frequency of various clinical features in <i>MYT1L</i> variant carriers.</p

Summary of demographic features, developmental milestones, medical complications and exome sequencing of cohort.

<p>Summary of demographic features, developmental milestones, medical complications and exome sequencing of cohort.</p

Gene expression profiling of <i>MYT1L</i> knockout cell line.

<p>(A)Enrichment analysis demonstrates enrichment for Gene Ontology Biological Process 2015 term gene expression (GO:0010467, adjusted p-value 0.00077, Z-score -2.34, combined score 16.77). (B)Enrichment analysis demonstrates enrichment for Gene Ontology Cellular Component 2015 terms nucleolus (GO: 0005730, adjusted p-value 0.0023, Z-score -2.21, combined score 13.43) and nucleoplasm (GO: 0005654, adjusted p-value 0.005853, Z-scre -2.08, combined score 11.4). (C)Enrichment analysis demonstrates enrichment for Reactome 2016 pathways Gene Expression_Homo Sapiens_R-HAS-74160 (adjusted p-value 2.2 x 10–7, Z-score -2.16, combined score 33) and Generic Transcription Pathway_Homo Sapiens_R-HAS-212436 (adjusted p-value 0.01586, Z-score -2.26, combined score 9.35). (D)Enrichment analysis demonstrates enrichment for OMIM disease term mental retardation (p-value 0.045, adjusted p-value 0.38, Z-score -1.32, combined score 1.27).</p

Structural effects of <i>MYT1L</i> missense variants.

<p>(A)Schematic diagram of MYT1L protein, the yellow boxes indicate zinc finger domains. The missense variants are indicated by arrows. (B)Model of the 2^nd and 3^rd zinc fingers of MYT1L bound to DNA. This is based upon the structure of the 4^th and 5^th zinc fingers of MYT1 (protein data bank file 2mf8), which have high sequence similarity to the 2^nd and 3^rd zinc fingers of MYT1L. The second zinc finger is in magenta, and the third finger in green. The beige spheres represent the zinc ions, with the CCHC zinc ligands shown in cyan. Replacement of L520 by proline is expected to disrupt the structure of the protein by preventing the formation of a tight turn. H524 and G527 are a zinc ligands, so replacement will also disrupt the structure. H560 and R569 are conserved residues directly involved in DNA binding. Image created using Pymol.</p