MECP2 Mutations Research Articles

Spectrum of MECP2 mutations in Iranian Azeri Turkish Rett syndrome patients

Rett syndrome is an X-linked dominant neurodevelopmental disorder that occurs mostly in females. De novo mutations in the MECP2 gene have an important role in the appearance of the features of this syndrome. We planned to study spectrum of MECP2 mutations in Rett syndrome patients and their clinical symptoms. A cohort of 29 patients referred by neurologists from Iranian Azeri Turks was screened. Then direct sequencing was utilized to characterize the spectrum of mutations in the MECP2 gene in Rett syndrome patients. A total of 10 different mutations on MECP2 gene were detected in 22 patients. We identified 2 (9%) frameshift, 10 (45.64%) nonsense, 8 (36.4%) missense mutations, and 2(9%) large deletions. In this cohort, one of the detected deletions was novel, namely 1023-1096del74nt. Random X chromosome inactivation in females’ cells and different MECP2 mutations can cause a phenotypic variability between patients. This is the first report regarding the spectrum of MECP2 mutation and phenotypic spectrum in Iranian Azeri Turks with Rett syndrome. Our finding confirms a high mutation frequency (75.8%) of MECP2 gene in Iranian Rett syndrome patients.

1028 Congenital Central Hypoventilation in a patient with MCEP2 duplication syndrome

Abstract Introduction Congenital central hypoventilation (CCHS) is a rare disorder due to impairment of autonomic nervous system clinically defined by a significantly reduced or abolished ventilatory response to hypercapnia and hypoxemia in the absence of pulmonary, neuromuscular, or cardiac disease. There is limited knowledge on associated respiratory manifestations and sleep-disordered breathing in children with the MECP2 duplication syndrome. Although sleep-disordered breathing and nocturnal hypoventilation are currently not well recognized in these children, we present a case of a patient with MECP2 mutation and congenital hypoventilation syndrome. Report of case(s) 24-week-old male born full-term via c-section presented with recurrent respiratory problems, laryngeal cleft, dysphagia, snoring and apneic episodes. Previous genetic work up showed chromosome 15q11.2 microdeletion. Past medical history was significant for neonatal ICU stay for respiratory distress immediately following birth. Tonsils are 1+ on exam. PSG showed profound central sleep apnea (CAI 300/h) with average apneic episodes lasted for 7 seconds and very significant periodic breathing (88%) and mild obstructive apnea. Mild hypoxemia was also seen with SpO2 in low 90s without any significant hypercapnia. Bradypnea with resp rate 10-20/m was seen. PHOX2B gene testing was negative. Genetic testing with SNP array showed MECP2 duplication syndrome. His development is delayed, currently at the age of 20 months, including cognitive, speech and motor function for which he is on therapy. Tracheostomy was recommended, however family preferred to continue with non-invasive ventilation while awaiting diaphragmatic pacing. Conclusion Respiratory manifestations in MECP2 duplication syndrome patients are common, with important impact and even a possible fatal outcome. Although sleep-disordered breathing and nocturnal hypoventilation is currently not cited as an important symptom in these children, there have been several case reports of CCHS associated with this. PSG should be considered in patients with MCEP2 duplication syndrome for timely diagnosis. Different treatment modalities (ENT surgery, CPAP and NIV) can be applied successfully to treat respiratory conditions associated with MECP2 duplication syndrome. Support (if any)

A Comprehensive and Integrative Approach to MeCP2 Disease Transcriptomics

Mutations in MeCP2 result in a crippling neurological disease, but we lack a lucid picture of MeCP2's molecular role. Individual transcriptomic studies yield inconsistent differentially expressed genes. To overcome these issues, we demonstrate a methodology to analyze all modern public data. We obtained relevant raw public transcriptomic data from GEO and ENA, then homogeneously processed it (QC, alignment to reference, differential expression analysis). We present a web portal to interactively access the mouse data, and we discovered a commonly perturbed core set of genes that transcends the limitations of any individual study. We then found functionally distinct, consistently up- and downregulated subsets within these genes and some bias to their location. We present this common core of genes as well as focused cores for up, down, cell fraction models, and some tissues. We observed enrichment for this mouse core in other species MeCP2 models and observed overlap with ASD models. By integrating and examining transcriptomic data at scale, we have uncovered the true picture of this dysregulation. The vast scale of these data enables us to analyze signal-to-noise, evaluate a molecular signature in an unbiased manner, and demonstrate a framework for future disease focused informatics work.

Mutations in the transcriptional regulator MeCP2 severely impact key cellular and molecular signatures of human astrocytes during maturation

Mutations in the MECP2 gene underlie a spectrum of neurodevelopmental disorders, most commonly Rett syndrome (RTT). We ask whether MECP2 mutations interfere with human astrocyte developmental maturation, thereby affecting their ability to support neurons. Using human-based models, we show that RTT-causing MECP2 mutations greatly impact the key role of astrocytes in regulating overall brain bioenergetics and that these metabolic aberrations are likely mediated by dysfunctional mitochondria. During post-natal maturation, astrocytes rely on neurons to induce their complex stellate morphology and transcriptional changes. While MECP2 mutations cause cell-intrinsic aberrations in the astrocyte transcriptional landscape, surprisingly, they do not affect the neuron-induced astrocyte gene expression. Notably, however, astrocytes are unable to develop complex mature morphology due to cell- and non-cell-autonomous aberrations caused by MECP2 mutations. Thus, MECP2 mutations critically impact key cellular and molecular features of human astrocytes and, hence, their ability to interact and support the structural and functional maturation of neurons.

Isogenic Human-Induced Pluripotent Stem-Cell-Derived Cardiomyocytes Reveal Activation of Wnt Signaling Pathways Underlying Intrinsic Cardiac Abnormalities in Rett Syndrome

Rett syndrome (RTT) is a severe neurodevelopmental disorder caused by MeCP2 mutations. Nonetheless, the pathophysiological roles of MeCP2 mutations in the etiology of intrinsic cardiac abnormality and sudden death remain unclear. In this study, we performed a detailed functional studies (calcium and electrophysiological analysis) and RNA-sequencing-based transcriptome analysis of a pair of isogenic RTT female patient-specific induced pluripotent stem-cell-derived cardiomyocytes (iPSC-CMs) that expressed either MeCP2wildtype or MeCP2mutant allele and iPSC-CMs from a non-affected female control. The observations were further confirmed by additional experiments, including Wnt signaling inhibitor treatment, siRNA-based gene silencing, and ion channel blockade. Compared with MeCP2wildtype and control iPSC-CMs, MeCP2mutant iPSC-CMs exhibited prolonged action potential and increased frequency of spontaneous early after polarization. RNA sequencing analysis revealed up-regulation of various Wnt family genes in MeCP2mutant iPSC-CMs. Treatment of MeCP2mutant iPSC-CMs with a Wnt inhibitor XAV939 significantly decreased the β-catenin protein level and CACN1AC expression and ameliorated their abnormal electrophysiological properties. In summary, our data provide novel insight into the contribution of activation of the Wnt/β-catenin signaling cascade to the cardiac abnormalities associated with MeCP2 mutations in RTT.

Genetic analysis of neurodevelopmental disorders in children

PurposeTo explore the genetic cause of children with unidentified etiology of neurodevelopmental disorders, thus providing references for the diagnosis, treatment and genetic counseling.Design and methodsChildren with neurodevelopmental disorders but unidentified etiology in the Child Healthcare Department, Children's Hospital of Nanjing Medical University from November 2018 to December 2021 were retrospectively analyzed. A total of 2 ml of peripheral venous blood was collected from the child and their parents for the whole exome sequencing (WES) and copy number variation (CNV) detection. Male children were subjected to fragile X syndrome testing to determine the genetic mutations. For those with positive results, Sanger sequencing was performed to explore the mutations in the gene sites and pedigrees.ResultsA total of 488 (33.5%) pathogenic variations were detected among 1,457 global developmental/intellectual disabilities (GDD/ID) children, including 362 (24.9%) cases of monogenic mutations, and 111 (7.6%) cases of chromosomal microdeletions or microduplications. There were 15/780 (1.92%) male children with fragile X syndrome. Single point mutations were detected in 277/362 (76.5%) and 85/362 (23.5%) male and female GDD/ID children, respectively, including 295 (81.5%) cases of missense mutations, 32 (8.8%) cases of frameshift mutations, 5 (2.2%) cases of non-sense mutations and 30 (8.3%) cases of splice site mutations. In addition, there were 166 (45.8%) cases of autosomal inheritance and 196 (54.2%) cases of X-linked inheritance. The X chromosome abnormalities were mostly observed in 362 GDD/ID children with monogenic mutations, including 15 cases of the AFF2 gene mutation, 13 cases of the MECP2 gene mutation and 12 cases of the HUWEI gene mutation. The CREBBP gene mutation was the most common autosome abnormality in GDD/ID children with monogenic mutations, which was detected in five cases. There were 74 cases of chromosomal microdeletions, 31 cases of chromosomal microduplications and six cases of both. A total of 114 novel pathogenic mutations responsible for GDD/ID were found, including four novel mutations in MECP2 and TRAPPC9 genes.ConclusionThe incidence of genetic abnormalities remains high in NDD children. Abundant novel mutations are responsible for GDD/ID in children, and can be used as references in the diagnosis of neurogenetic diseases.

RF14 | PSAT120 X-Linked Central Precocious Puberty Associated with MECP2 Defects

Abstract Methyl-CpG-binding protein 2 (MECP2) is a chromatin-associated protein that can both activate and repress transcription, playing an essential role in neuronal maturation. MECP2 is encoded by an X-linked gene (chromosome Xq28) with high expression in the brain, including the hypothalamic region. Loss-of-function mutations in MECP2 are usually associated with Rett syndrome, a rare genetic disorder characterized by normal early development followed by regression of acquired skills, such as purposeful hand movements and the ability to communicate, repetitive hand stereotypies, slowed brain growth, seizures, and intellectual disability with female predominance. Notably, early pubertal development (early thelarche, pubarche and, less often, menarche) has been demonstrated in girls with Rett syndrome. In this original study, a total of 329 CPP patients (308 girls and 21 boys) were investigated for MECP2 defects. Familial cases were identified in 38% of this CPP cohort. First, 129 CPP patients were enrolled for multigene sequencing studies (whole-exome sequencing n=58; targeted gene sequencing n=71) as part of genetic investigations based on large-scale approaches. Three rare heterozygous sequence variants predicted to be deleterious in MECP2 gene were identified in 5 girls from 4 unrelated families with CPP: the p.Arg97Cys de novo missense variant in two monozygotic twin sisters with CPP and microcephaly; the p.Ser176Arg de novo missense variant in one girl with sporadic CPP, obesity and autism; and the p.Ala6_Ala8dup insertion in two unrelated girls with sporadic CPP (one with a maternally inherited variant). To expand the investigation for potentially damaging sequence variants of MECP2, a larger multiethnic cohort of 200 CPP patients was further analyzed through Sanger sequencing. One rare heterozygous 3'UTR insertion in MECP2 (c.*36_*37insT) was identified in two unrelated girls with sporadic CPP (one with a maternally inherited variant and other with a de novo variant). None of these MECP2 variants have been previously reported in Rett syndrome cases. The girls with CPP associated with MECP2 defects did not manifest typical Rett syndrome. The three patients with more deleterious MECP2 variants, according to in silico prediction tools, had neurobehavioral phenotypes, likely corresponding to a genotype-phenotype correlation. Immunohistochemistry and immunofluorescence studies were performed in pubertal female mice. Abundant staining for Mecp2 was demonstrated in multiple hypothalamic nuclei (arcuate, suprachiasmatic, and paraventricular) and in the median eminence. Co-localization of Mecp2 and GnRH within GnRH neurons was suggested in double labelling experiments. Hence, Mecp2 expression was demonstrated in key hypothalamic nuclei responsible for GnRH regulation in female mice. In conclusion, we have identified rare dominant MECP2 defects in multiple unrelated girls with CPP with or without mild neurodevelopmental abnormalities, revealing a new X-linked form of premature reactivation of the hypothalamic-pituitary-gonadal axis. Presentation: Saturday, June 11, 2022 1:00 p.m. - 3:00 p.m., Sunday, June 12, 2022 12:30 p.m. - 12:35 p.m.

An investigation of the sleep macrostructure of girls with Rett syndrome

Objective/backgroundMethyl-CpG-binding protein 2 (MeCP2) is of utmost importance in neuronal function. We aim to characterize phenotypic traits in the sleep of individuals with Rett Syndrome (RTT, OMIM # 312750), a rare disorder predominantly caused by mutations of the MECP2 gene. Patients/methodsAn overnight polysomnographic recording was performed. Outcomes investigated were parameters of nocturnal sleep macrostructure, and sample stratification per genetic and clinical characteristics, and six key features of clinical severity was applied. ResultsThe sleep of our 21 RTT female subjects with a mutant MECP2 gene, aged 8.8 ± 5.4 years, showed no significant differences within strata. However, compared to a normative dataset, we found longer duration of wake time after sleep onset and total sleep time (TST) but shorter sleep onset latency, in RTT. Regarding the proportion of sleep stages per TST, higher stage N3 (%) with lower stage N2 (%) and REM (%) were generally seen. Such abnormalities became more uniformly expressed at the severe level of clinical features, particularly for hand functioning and walking. ConclusionsRTT girls with MECP2 mutations in our study demonstrated an increased deep sleep and reduced rapid eye movement sleep proportion, which is mostly allied with their hand dysfunction severity. Poor sleep-on/off switching in RTT since embryogenesis is possibly linked to (psycho)motor impairment in the cases with MECP2 mutations.

Wide spectrum of neuronal and network phenotypes in human stem cell-derived excitatory neurons with Rett syndrome-associated MECP2 mutations

Rett syndrome (RTT) is a severe neurodevelopmental disorder primarily caused by heterozygous loss-of-function mutations in the X-linked gene MECP2 that is a global transcriptional regulator. Mutations in the methyl-CpG binding domain (MBD) of MECP2 disrupt its interaction with methylated DNA. Here, we investigate the effect of a novel MECP2 L124W missense mutation in the MBD of an atypical RTT patient with preserved speech in comparison to severe MECP2 null mutations. L124W protein had a limited ability to disrupt heterochromatic chromocenters due to decreased binding dynamics. We isolated two pairs of isogenic WT and L124W induced pluripotent stem cells. L124W induced excitatory neurons expressed stable protein, exhibited increased input resistance and decreased voltage-gated Na+ and K+ currents, and their neuronal dysmorphology was limited to decreased dendritic complexity. Three isogenic pairs of MECP2 null neurons had the expected more extreme morphological and electrophysiological phenotypes. We examined development and maturation of L124W and MECP2 null excitatory neural network activity using micro-electrode arrays. Relative to isogenic controls, L124W neurons had an increase in synchronous network burst frequency, in contrast to MECP2 null neurons that suffered a significant decrease in synchronous network burst frequency and a transient extension of network burst duration. A biologically motivated computational neural network model shows the observed changes in network dynamics are explained by changes in intrinsic Na+ and K+ currents in individual neurons. Our multilevel results demonstrate that RTT excitatory neurons show a wide spectrum of morphological, electrophysiological and circuitry phenotypes that are dependent on the severity of the MECP2 mutation.

Sleep Respiratory Disturbances in Girls with Rett Syndrome.

Individuals with Rett Syndrome (RTT), a rare neurodevelopmental disorder, present disordered breathing during wakefulness. Whilst findings on breathing during sleep are contradictory, the relation between sleep breathing and their clinical features, genetic characteristics, age, and sleep phase is rarely investigated, which is the objective of this study. Overnight polysomnography (PSG) was performed. Sleep macrostructure parameters were compared between the RTT subjects with and without sleep-disordered breathing (SDB). The association between the apnea–hypopnea index (AHI) with age at PSG was tested. Particularly for RTT subjects with SDB, the respiratory indexes in REM and NREM sleep were compared. Stratified analyses per clinical characteristics, genetic characteristics, and clinical features’ severity were performed. Non-parametric statistics were applied. A sample of 11 female RTT subjects, aged 8.69 ± 5.29 years with ten confirmed with MECP2 mutations, were studied. The average AHI was 3.94 ± 1.19/h TST, of which eight (72.73%) had obstructive sleep apnea, i.e., six in 1/h TST ≤ AHI ≤ 5/h TST, and two in AHI > 5/h TST. The mean SpO2% was 81.00 ± 35.15%. The AHI was not significantly correlated with their age at PSG (rs = −0.15, p = 0.67). Sleep macrostructure in SDB-absent and SDB-present groups was not different. Respiratory indexes in those with obstructive sleep apnea showed no difference between REM and NREM sleep nor any of the strata. In our clinical sample, more than half of the RTT subjects with MECP2 mutations had obstructive sleep apnea in both NREM and REM sleep which was unrelated to their clinical features. Our results also indicated hypoxemia throughout nocturnal sleep in RTT. To conclude, our results suggest that disordered breathing during sleep is prevalently present in RTT as an independent clinical feature.

Meta-Analysis Identifies BDNF and Novel Common Genes Differently Altered in Cross-Species Models of Rett Syndrome.

Rett syndrome (RTT) is a rare disorder and one of the most abundant causes of intellectual disabilities in females. Single mutations in the gene coding for methyl-CpG-binding protein 2 (MeCP2) are responsible for the disorder. MeCP2 regulates gene expression as a transcriptional regulator as well as through epigenetic imprinting and chromatin condensation. Consequently, numerous biological pathways on multiple levels are influenced. However, the exact molecular pathways from genotype to phenotype are currently not fully elucidated. Treatment of RTT is purely symptomatic as no curative options for RTT have yet to reach the clinic. The paucity of this is mainly due to an incomplete understanding of the underlying pathophysiology of the disorder with no clinically useful common disease drivers, biomarkers, or therapeutic targets being identified. With the premise of identifying universal and robust disease drivers and therapeutic targets, here, we interrogated a range of RTT transcriptomic studies spanning different species, models, and MECP2 mutations. A meta-analysis using RNA sequencing data from brains of RTT mouse models, human post-mortem brain tissue, and patient-derived induced pluripotent stem cell (iPSC) neurons was performed using weighted gene correlation network analysis (WGCNA). This study identified a module of genes common to all datasets with the following ten hub genes driving the expression: ATRX, ADCY7, ADCY9, SOD1, CACNA1A, PLCG1, CCT5, RPS9, BDNF, and MECP2. Here, we discuss the potential benefits of these genes as therapeutic targets.

Aberrant brain functional and structural developments in MECP2 duplication rats

Transgenic animal models with homologous etiology provide a promising way to pursue the neurobiological substrates of the behavioral deficits in autism spectrum disorder (ASD). Gain-of-function mutations of MECP2 cause MECP2 duplication syndrome, a severe neurological disorder with core symptoms of ASD. However, abnormal brain developments underlying the autistic-like behavioral deficits of MECP2 duplication syndrome are rarely investigated. To this end, a human MECP2 duplication (MECP2-DP) rat model was created by the bacterial artificial chromosome transgenic method. Functional and structural magnetic resonance imaging (MRI) with high-field were performed on 16 male MECP2-DP rats and 15 male wildtype rats at postnatal 28 days, 42 days, and 56 days old. Multimodal fusion analyses guided by locomotor-relevant metrics and social novelty time separately were applied to identify abnormal brain networks associated with diverse behavioral deficits induced by MECP2 duplication. Aberrant functional developments of a core network primarily composed of the dorsal medial prefrontal cortex (dmPFC) and retrosplenial cortex (RSP) were detected to associate with diverse behavioral phenotypes in MECP2-DP rats. Altered developments of gray matter volume were detected in the hippocampus and thalamus. We conclude that gain-of-function mutations of MECP2 induce aberrant functional activities in the default-mode-like network and aberrant volumetric changes in the brain, resulting in autistic-like behavioral deficits. Our results gain critical insights into the biomarker of MECP2 duplication syndrome and the neurobiological underpinnings of the behavioral deficits in ASD.

Neuronal Ceroid Lipofuscinoses Presenting as Rett-like Phenotype: A Two-Case Report From Thailand

BackgroundNeuronal ceroid lipofuscinoses (NCLs) (hereafter described as CLN disease) comprise a rare and life-limiting set of genetically inherited neurodegenerative disorders that are characterized by abnormal lysosomal storage. The NCL disorders are, collectively, the most common group of degenerative brain disorders in children. Patient DescriptionsWe report two cases of CLN disease that were diagnosed and treated at the Department of Pediatrics, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand. Both cases of CLN disease (CLN1 and CLN6 diagnosed in 2016 and 2017, respectively) profiled in this report presented with clinical features of Rett syndrome. In the first case, a 2-year-old girl presented with Rett-like clinical features, including global developmental regression and hand-wringing action. Single-gene analysis of the MECP2 gene was negative. However, PPT1 gene sequencing revealed a novel homozygous frameshift mutation, c.629_630dupGT (p.Ile211Valfs∗10). In the second case, a 7.5-year-old girl presented with ataxia, progressive myoclonic epilepsy, and Rett-like hand-wringing. A c.794_796delCCT variant in the CLN6 gene was identified by whole-exome sequencing. Fingerprint bodies from electron microscopy of the skin also supported a diagnosis of CLN disease in our second case. DiscussionPresentation with clinical features of Rett syndrome has only been reported in patients diagnosed with CLN1 and CLN7 disease, and never in those with CLN6. ConclusionsPhysicians should suspect and investigate for CLN disease in patients with Rett-like phenotype who are negative for MECP2 mutation, especially in patients with visual impairment and early prominent brain atrophy.

Cell type-specific DNA methylome signatures reveal epigenetic mechanisms for neuronal diversity and neurodevelopmental disorder.

DNA methylation plays a critical function in establishing and maintaining cell identity in brain. Disruption of DNA methylation-related processes leads to diverse neurological disorders. However, the role of DNA methylation characteristics in neuronal diversity remains underexplored. Here, we report detailed context-specific DNA methylation maps for GABAergic, glutamatergic (Glu) and Purkinje neurons, together with matched transcriptome profiles. Genome-wide mCH levels are distinguishable, while the mCG levels are similar among the three cell types. Substantial CG-differentially methylated regions (DMRs) are also seen, with Glu neurons experiencing substantial hypomethylation events. The relationship between mCG levels and gene expression displays cell type-specific patterns, while genic CH methylation exhibits a negative effect on transcriptional abundance. We found that cell type-specific CG-DMRs are informative in terms of represented neuronal function. Furthermore, we observed that the identified Glu-specific hypo-DMRs have a high level of consistency with the chromatin accessibility of excitatory neurons and the regions enriched for histone modifications (H3K27ac and H3K4me1) of active enhancers, suggesting their regulatory potential. Hypomethylation regions specific to each cell type are predicted to bind neuron type-specific transcription factors. Finally, we show that the DNA methylation changes in a mouse model of Rett syndrome, a neurodevelopmental disorder caused by the de novo mutations in MECP2, are cell type- and brain region-specific. Our results suggest that cell type-specific DNA methylation signatures are associated with the functional characteristics of the neuronal subtypes. The presented results emphasize the importance of DNA methylation-mediated epigenetic regulation in neuronal diversity and disease.

MeCP2 loss-of-function dysregulates microRNAs regionally and disrupts excitatory/inhibitory synaptic transmission balance.

Rett syndrome is a leading cause of intellectual disability in females primarily caused by loss of function mutations in the transcriptional regulator MeCP2. Loss of MeCP2 leads to a host of synaptic phenotypes that are believed to underlie Rett syndrome pathophysiology. Synaptic deficits vary by brain region upon MeCP2 loss, suggesting distinct molecular alterations leading to disparate synaptic outcomes. In this study, we examined the contribution of MeCP2's newly described role in miRNA regulation to regional molecular and synaptic impairments. Two miRNAs, miR-101a and miR-203, were identified and confirmed as upregulated in MeCP2 KO mice in the hippocampus and cortex, respectively. miR-101a overexpression in hippocampal cultures led to opposing effects at excitatory and inhibitory synapses and in spontaneous and evoked neurotransmission, revealing the potential for a single miRNA to broadly regulate synapse function in the hippocampus. These results highlight the importance of regional alterations in miRNA expression and the specific impact on synaptic function with potential implications for Rett syndrome.

Pattern decorrelation in the mouse medial prefrontal cortex enables social preference and requires MeCP2

Sociability is crucial for survival, whereas social avoidance is a feature of disorders such as Rett syndrome, which is caused by loss-of-function mutations in MECP2. To understand how a preference for social interactions is encoded, we used in vivo calcium imaging to compare medial prefrontal cortex (mPFC) activity in female wild-type and Mecp2-heterozygous mice during three-chamber tests. We found that mPFC pyramidal neurons in Mecp2-deficient mice are hypo-responsive to both social and nonsocial stimuli. Hypothesizing that this limited dynamic range restricts the circuit’s ability to disambiguate coactivity patterns for different stimuli, we suppressed the mPFC in wild-type mice and found that this eliminated both pattern decorrelation and social preference. Conversely, stimulating the mPFC in MeCP2-deficient mice restored social preference, but only if it was sufficient to restore pattern decorrelation. A loss of social preference could thus indicate impaired pattern decorrelation rather than true social avoidance.

MECP2 Dysautonomia Phenotypes in Boys

BackgroundRecognizing and identifying dysautonomia would facilitate the diagnosis and management of MECP2 mutations in boys. We aimed to explore the prevalence of dysautonomia symptoms in boys with MECP2 mutations. MethodWe conducted a national, retrospective study (2000-2020) of medical records from boys who were aged less than 18 years when diagnosed with a pathogenic, or likely pathogenic, variant in the MECP2 gene. We systematically looked for dysautonomic signs in the cardiovascular, respiratory, gastrointestinal, and thermoregulatory systems. ResultsNine of the 13 cases had at least one system affected by dysautonomia. Two patient subgroups were identified: (1) patients who were ambulatory with intellectual or learning disabilities (n = 6/13 cases) and (2) patients who were unable to walk normally with severe encephalopathy (n = 7/13 cases). Dysautonomic signs were found in both subgroups: 7 of seven patients in the severe array subgroup and 2 of six in the mild array subgroup. ConclusionsThese results support MECP2 testing and dysautonomia investigations in both young males who present with encephalopathy and those with intellectual disabilities.

253 Economic burden of care and treatment options for Rett syndrome: two systematic literature reviews

Rett syndrome, a rare disorder caused by MECP2 mutation, causes severe developmental impairment in afflicted girls. We performed two literature reviews in June 2018 to assess Rett syndrome clinical trials (MEDLINE/Embase/ClinicalTrials.gov/Cochrane Library) and the economic burden of care (Medline/Embase/Cochrane Library/Database of Abstracts of Reviews and Effects). The economic burden search yielded 133 articles; intervention type/costs were extracted from 9, representing 4 studies. Enteral feeding/assisted walking increased the risk of respiratory-related hospital admissions, while length-of-stay was lower in younger patients. Mean recovery-stay after scoliosis-correcting surgery was 18.2/12.3 days in each of two studies. Care integration improved outcomes and reduced costs. The clinical trials search yielded 652 articles; efficacy/safety were extracted from 28, representing 20 studies (15 randomized controlled trials, 5 single-arm; N=8–82; follow-up 1–26 months). Nineteen focused on pharmacological symptom treatment; 1 examined environmental enrichment effects; most common primary endpoints: Rett syndrome Gross Motor Scale, Clinical Severity Score, Motor and Behavioral Assessment, and the Anxiety Depression and Mood Scale. Naltrexone, trofinetide, and mecasermin demonstrated clinical benefits, but most treat- ments yielded no significant improvement. Clinical practice guidelines and treatment patterns data were limited. There is demand for treatments targeting the underlying cause, such as gene therapy. Previously presented after 08/2019.jloukes879@avexis.com158

Clinical and genetic analysis of two rare male patients with Rett syndrome

To conduct clinical and genetic analysis of two male patients with atypical Rett syndrome. Collection of clinical data in the two patients and these parents; whole exome sequencing (WES) was used to detect the potential variants, which were verified by Sanger sequencing. X chromosome inactivation (XCI) detection is performed in the Patient 1's mother to detect the allelic expression difference of the MECP2 gene. Patient 1, a 5-year and 10-month-old boy, had mental disorders and mild intellectual disability (ID) (IQ: 54), whose mother had ID. Patient 2 was a 9-month and 18-day-old male presented with recurrent infections, respiratory insufficiency, hypotonia and global developmental delay. WES indentified a hemizygous mutation, c.499C>T (p.R167W), in the MECP2 gene in patient 1, which was inherited from his mother. The inactivation of X chromosome is skewed, and the expression ratio of wild-type and mutant MECP2 is 100%:0. Patient 2 was found a de novo splicing mutation, c.62+2_62+3del in the MECP2 gene. They were both reported pathogenic variant related to Rett syndrome. c.499C>T (p.R167W) was defined as likely pathogenic (PS1+PM2+PP3) and c.62+2_62+3del was pathogenic (PVS1+PM2+PM6) based on American College of Medical Genetics and Genomics standards and guidelines. Both the two patients were diagnosed with rare male Rett syndrome, which had atypical clinical manifestations and large difference. Above foundings have revealed novel phenotypes in Chinese male patients with Rett syndrome.

Developing a novel DNA methylation risk score for survival and identification of prognostic gene mutations in endometrial cancer: a study based on TCGA data.

Few studies have focused on DNA methylation in endometrial cancer. The aim of our study is identify its role in endometrial cancer prognosis. A publicly available dataset was retrieved from The Cancer Genome Atlas. For validation of expression alteration due to methylation, RNA sequencing data were obtained from other independent cohorts. MethSurv was used to search for candidate CpG probes, which were then filtered by least absolute shrinkage and selection operator Cox regression and multivariate Cox regression analyses to identify final set of CpG probes for overall survival. A methylation-based risk model was developed and receiver operating characteristic analysis with area under curve was used for evaluation. Patients were divided into high- and low-risk groups using an optimal cut-off point. Comprehensive bioinformatic analyses were conducted to identify hub genes, key transcription factors, and enriched cancer-related pathways. Kaplan-Meier curve was used for survival analysis. A 5-CpG signature score was established. Its predictive value for 5-year overall survival was high, with area under curve of 0.828, 0.835 and 0.816 for the training, testing and entire cohorts. cg27487839 and cg12885678 had strong correlation with their gene expression, XKR6 and PTPRN2, and lower PTPRN2 expression was associated with poorer survival in both The Cancer Genome Atlas and the validation datasets. Low-risk group was associated with significantly better survival. Low-risk group harboured more mutations in hub genes and key transcription factors, and mutations in SP1 and MECP2 represented favourable outcome. We developed a methylation-based prognostic stratification system for endometrial cancer. Low-risk group was associated with better survival and harboured more mutations in the key regulatory genes.