Diagnosis Of RTT Research Articles

Genomic analysis in Chilean patients with suspected Rett syndrome: keep a broad differential diagnosis.

Introduction: Rett syndrome (RTT, MIM #312750) is a rare genetic disorder that leads to developmental regression and severe disability and is caused by pathogenic variants in the MECP2 gene. The diagnosis of RTT is based on clinical features and, depending on resources and access, on molecular confirmation. There is scarce information on molecular diagnosis from patients in Latin America, mostly due to limited availability and coverage of genomic testing. This pilot study aimed to implement genomic testing and characterize clinical and molecular findings in a group of Chilean patients with a clinical diagnosis of RTT. Methods: Twenty-eight patients with suspected RTT underwent characterization of phenotypic manifestations and molecular testing using Clinical Exome SolutionTM CES_V2 by SOPHiA Genetics. Data was analyzed using the commercial bioinformatics platform, SOPHiA DDMTM. A virtual panel of 34 genes, including MECP2 and other genes that are in the differential diagnosis of RTT, was used to prioritize initial analyses, followed by evaluation of the complete exome sequence data. Results: Twelve patients (42.8% of participants) had variants in MECP2, of which 11 (39.2%) were interpreted as pathogenic/likely pathogenic (P/LP), thus confirming the diagnosis of RTT in them. Eight additional patients (28.5%) harbored ten variants in nine other genes. Four of these variants were interpreted as P/LP (14.2%) (GRIN2B, MADD, TRPM3 and ZEB2) resulting in alternative neurodevelopmental diagnoses, and six were considered of uncertain significance. No evident candidate variant was found for eight patients. Discussion: This study allowed to reach a diagnosis in half of the participants. The diagnosis of RTT was confirmed in over a third of them, while others were found to have alternative neurodevelopmental disorders. Further evaluation is needed to identify the cause in those with negative or uncertain results. This information is useful for the patients, families, and clinicians to guide clinical management, even more so since the development of novel therapies for RTT. We also show the feasibility of implementing a step-wide approach to genomic testing in a setting with limited resources.

Prevalence of Endocrinopathies in a Cohort of Patients with Rett Syndrome: A Two-Center Observational Study.

Systematic data on endocrinopathies in Rett syndrome (RTT) patients remain limited and inconclusive. The aim of this retrospective observational two-center study was to assess the prevalence of endocrinopathies in a pediatric population of RTT patients. A total of 51 Caucasian patients (47 girls, 4 boys) with a genetically confirmed diagnosis of RTT were enrolled (mean age 9.65 ± 5.9 years). The patients were referred from the Rett Center of two Italian Hospitals for endocrinological evaluation. All the study population underwent clinical and auxological assessments and hormonal workups. MeCP2 mutations were detected in 38 cases (74.5%), CDKL5 deletions in 11 (21.6%), and FOXG1 mutations in 2 (3.9%). Overall, 40 patients were treated with anti-seizure medications. The most frequent endocrinological finding was short stature (47%), followed by menstrual cycle abnormalities (46.2%), weight disorders (45.1%), low bone mineral density (19.6%), hyperprolactinemia (13.7%) and thyroid disorders (9.8%). In the entire study population, endocrinopathies were significantly more frequent in patients with MeCP2 mutations (p = 0.0005), and epilepsy was more frequent in CDKL5 deletions (p = 0.02). In conclusion, our data highlighted that endocrinopathies are not rare in RTT, especially in patients with MeCP2 deletions. Therefore, in the context of a multidisciplinary approach, endocrinological evaluation should be recommended for RTT patients.

Sleep and the Social Profiles of Individuals With Rett Syndrome

BackgroundThis study investigates the distinctive social behaviors observed in individuals with Rett syndrome (RTT), characterized by the loss of spoken language, impaired eye gaze communication, gait abnormalities, and sleep issues. The research aims to identify social profiles in RTT and explore their correlation with sleep, sleep-disordered breathing (SDB), and daytime sleepiness. MethodsStandard overnight sleep macrostructure and respiratory parameters were assessed. Extracting 25 social-related items and one for daytime sleepiness from the Rett Syndrome Behavioral Questionnaire, factor analysis was applied to establish latent social profiles. These profiles were then correlated with sleep parameters. The nonparametric Mann-Whitney U test compared social profiles based on the presence of SDB (defined by an apnea-hypopnea index greater than one per hour) and daytime sleepiness. ResultsThe study involved 12 female subjects with confirmed RTT diagnoses and MECP2 mutations, aged 8.54 ± 5.30 years. The Rett Syndrome Behavioral Questionnaire revealed a total average score of 25.83 ± 12.34, indicating varying degrees of social impairments. Comprising 25 social-related items, factor analysis yielded four social profiles: “interactive motricity,” “mood change,” “anxiety/agitation,” and “gazing.” Longer sleep onset latency correlated with increased socio-behavioral impairments, particularly in interactive motricity reduction. Conversely, higher rapid eye movement sleep was associated with fewer interactive socio-motor behaviors. No significant differences in social profiles were found concerning the presence of SDB or daytime sleepiness. ConclusionsThe findings suggest four distinct social profiles in RTT individuals, hinting at shared disrupted circuits between sensorimotor functioning and sleep-related neuronal pathways. Despite the absence of differences in SDB or daytime sleepiness, the study highlights the relationship between sleep parameters, such as sleep onset latency and rapid eye movement sleep, and socio-behavioral outcomes in RTT with MECP2 mutations.

Genetic Instability and Disease Progression of Indian Rett Syndrome Patients.

Rett syndrome (RTT) is the rare neurodevelopmental disorder caused by mutations in methyl CpG binding protein 2 (MECP2) gene with a prevalence of 1:10,000 worldwide. The hallmark clinical features of RTT are developmental delay, microcephaly, repetitive behaviours, gait abnormalities, respiratory abnormalities and seizures. Still, the understanding on the diagnosis of RTT among clinicians are less. The aim of our work was to study various clinical manifestations and a spectrum of MECP2 genetic heterogeneity in RTT patients from South Indian population. We screened 208 autistic patients and diagnosed 20 RTT patients, who were further divided into classical RTT (group I; N = 11) and variant RTT (group II; N = 9). The clinical severity of RTT was measured using RSSS, RSBQ, SSI, SSS and RTT gross motor scale. The biochemical analysis showed that thyroid-stimulating hormone (TSH), plasma dopamine and cholesterol levels were higher in group I when compared to group II, whereas the level of blood pressure, calcium, ferritin and high-density lipoprotein levels were significantly decreased in both RTT groups, when compared to the control group. The genetic mutational spectrum of MECP2 mutations were found in 12/20 of RTT patients, which revealed the occurrence of 60% pathogenic mutation and 20% unknown mutation and it was correlated with the clinical finding of respiratory dysfunction, scoliosis and sleeping problems. The significant results of this study provided clinical and genetic aspects of RTT diagnosis and proposed the clinicians to screen abnormal cholesterol, calcium and TSH levels tailed with MECP2 gene mutations for early prognosis of disease severity.

Rett Syndrome-Associated Scoliosis: Analysis of National Trends and Treatment Patterns of a Rare Indication for Posterior Instrumented Fusion.

Retrospective database cohort study. To evaluate U.S. treatment trends and inpatient outcomes for children undergoing posterior spinal fusion (PSF) for Rett syndrome (RTT)-associated scoliosis (RAS). RTT is a rare, sporadic neurodevelopmental disorder presenting in childhood with developmental regression, ataxia, and seizures. RAS occurs in 50% to 80% of cases of RTT, but little is known about the case volume and perioperative experience for children undergoing PSF. Using the International Classification of Diseases Ninth and 10th revision codes in the national Kids' Inpatient Database, we identified children with RTT who underwent PSF from 2000 to 2019. Annual case volumes were analyzed. Clinical characteristics and outcomes were compared with those of a cohort of patients with neuromuscular scoliosis (NMS). Among 220 patients with RAS, 216 (98.2%) were females (mean age at surgery: 12.3±3.3yr). Surgical case incidence steadily increased over 19 years, with more RAS admissions in the South (31.4%). Overall, patients with RAS demonstrated a higher mean Elixhauser Comorbidity Index score (2 vs . 1, P < 0.001) and had more perioperative complications (41.4% vs . 18%, P < 0.001) than patients with NMS. RTT diagnosis independently predicted higher odds of any complications (odds ratio: 1.98, P < 0.001) and increased length of stay (odds ratio: 1.18, P = 0.009) for admissions for PSF. Surgical treatment for RAS is rare but increased over a 19-year period. Cases appear to be clustering by region, with the highest proportion in the South. The higher Elixhauser Comorbidity Index in RAS patients predicted higher costs, longer hospital stays, more complications (particularly respiratory), and more nonroutine discharge disposition than in other patients with NMS. RTT was independently associated with higher odds of complications and longer length of stay. Because RAS cases appear to be increasing in number, future studies should emphasize methods to reduce morbidity and investigate deformity-specific metrics to help better understand this population.

Rett-like Phenotypes in HNRNPH2-Related Neurodevelopmental Disorder.

Rett Syndrome (RTT) is a neurodevelopmental disorder with a prevalence of 1:10,000 to 15,000 females worldwide. Classic Rett Syndrome presents in early childhood with a period of developmental regression, loss of purposeful hand skills along with hand stereotypies, gait abnormalities, and loss of acquired speech. Atypical RTT is diagnosed when a child shows some but not all the phenotypes of classic RTT, along with additional supporting criteria. Over 95% of classic RTT cases are attributed to pathogenic variants in Methyl-CpG Binding Protein 2 (MECP2), though additional genes have been implicated in other RTT cases, particularly those with the atypical RTT clinical picture. Other genetic etiologies have emerged with similar clinical characteristics to RTT Syndrome. Our team has characterized HNRNPH2-related neurodevelopmental disorder (HNRNPH2-RNDD) in 33 individuals associated with de novo pathogenic missense variants in the X-linked HNRNPH2 gene, characterized by developmental delay, intellectual disability, seizures, autistic-like features, and motor abnormalities. We sought to further characterize RTT clinical features in this group of individuals by using caregiver report. Twenty-six caregivers completed electronic surveys, with only 3 individuals having previously received an atypical RTT diagnosis, and no individuals with a typical RTT diagnosis. Caregivers reported a high number of behaviors and/or phenotypes consistent with RTT, including the major criteria of the syndrome, such as regression of developmental skills and abnormal gait. Based on the survey results, 12 individuals could meet the diagnostic clinical criteria for atypical RTT Syndrome. In summary, individuals with HNRNPH2-RNDD exhibit clinical characteristics that overlap with those of RTT, and therefore, HNRNPH2-RNDD, should be considered on the differential diagnosis list with this clinical picture.

Clinical and genetic correlations of scoliosis in Rett syndrome

AimTo identify the clinical features correlating with the presence and severity of scoliosis in girls with Rett syndrome (RTT).MethodSeventy-five girls with a clinical and genetically determined diagnosis of RTT participated in this cross-sectional study. Clinical scales administered included the Rett assessment rating scale, the modified Ashworth scale, the Rett syndrome motor evaluation scale, the PainAD, and the scale of evaluation of purposeful hand function. Multivariable analyses, such as ordinal logistic regression and ANCOVA, were used to assess the correlation between these scales and a clinical score of scoliosis.ResultsAbout 60% of patients had scoliosis, in general mild or moderate. The severity of scoliosis correlated with age and important neurological factors such as muscular hypertonus and hyperreflexia, standing, walking (level walking and on stairs), and postural transitions. No association was found with global disease severity, hand function, pain, or type of genetic mutation.InterpretationScoliosis is a relevant problem in RTT. It should be carefully monitored along the life span, especially in conjunction with (loco-)motor impairment in these patients.

Comparing Advanced with Basic Telerehabilitation Technologies for Patients with Rett Syndrome-A Pilot Study on Behavioral Parameters.

The aim of this study is to compare the performances of patients with Rett syndrome that were undergoing advanced telerehabilitation (ATR) and patients that were undergoing basic telerehabilitation (BTR). It was hypothesized that patients that were undergoing ATR training would have better improvement in nearly all the motor and cognitive scale scoring activities that were administered, thus showing reduced disability. A total of 20 young girls and women with a diagnosis of RTT, ranging from age 4 to 31 years old (Median: 12.50; IQR: 9.50–17.25) underwent a pre-test, treatment post-test 1, treatment, and post-test 2 procedure. The treatment consisted of either ATR or BTR, lasting 10 weeks with three sessions a week of about an hour. The results showed that the group with advanced telerehabilitation improved their performance better than the control group only in some neuropsychological measurements. The results are discussed in the light of critical factors of telerehabilitation.

Skype Supervised, Individualized, Home-Based Rehabilitation Programs for Individuals With Rett Syndrome and Their Families - Parental Satisfaction and Point of View.

Individuals with Rett syndrome (RTT) experience impaired gross motor skills limiting their capacity. Therefore, they need support to participate in physical activities, and it is crucial to work with primary caregivers when developing appropriate strategies, thereby leading to an active lifestyle. There is limited evidence supporting the effectiveness of remotely supported physical activity interventions. This project aimed to evaluate the effects of a skype-based, telehealth-delivered physical activity program carried out by participants’ parents at home. This article will focus on parental points of view. A mixed-methods design evaluating parental satisfaction was conducted. Forty participants with a confirmed genetic diagnosis of RTT and their families were recruited. The intervention included a 12-week individualized daily physical activity program carried out by participants’ parents and bi-weekly supervised by expert therapists. Parents’ impressions and feelings related to the program implementation were collected throughout semi-structured interviews, and an ad hoc developed questionnaire and discussed. The current project results suggest that a remote physical rehabilitation program, supported fortnightly by video calls, represents an effective way of conducting a remote physical therapy intervention for this population and that it can be easily carried out at home by primary caregivers, promoting positive functional changes, without bringing feelings of frustration due to the required workload. The strategies that families have learned during the program to support the motor activities of their daughters represent an easily performed set of tools that they can maintain and use in everyday life even after the cessation of the program.

Methyl-CpG-binding protein 2 gene mutations and its association with epilepsy: a single centre study from the Indian subcontinent

Rett syndrome (RTT) is an X-linked disorder caused by mutations in MECP2 in majority of cases. It is characterized by arrested development between 6 and 18 months of age, regression of acquired hand skills and speech, stereotypic hand movements, gait abnormalities and seizures. There are a very few studies in India which illustrates mutation spectrum in RTT. None of the studies have correlated seizures with the genotype. This study describes the phenotype and genotype spectrum in children with RTT syndrome and analyses the association of epilepsy with various clinical features and molecular findings. All children with RTT in our cohort had global developmental delay. Genetic diagnosis identified mutations of the MECP2 in all 25 children where RTT was suspected. We have identified point mutations in 20 patients, one insertion and four deletions by Sanger sequencing, namely c.1164_1207 (44 bp), c.1165_1207 (43 bp), c.1157_1197 (41 bp) del and c.1157_1188 (32 bp). Clinically, none of the patients with deletion had seizures. We identified one novel insertion variant c.337_338 (p.S113Ffs*9). All the deletions were located in the C-terminal region. Majority of the mutations (22/25) were identified in exon 4 which comprised of nonsense and missense types. Screening of hotspot mutations in exon 4 should be the first line evaluation in diagnosis of RTT. Molecular testing could help in specific management of seizures in RTT.

Genetic and clinical variations in a Norwegian sample diagnosed with Rett syndrome

Background and purposeRett syndrome (RTT) is a neurodevelopmental disorder mainly caused by mutations in MECP2. The diagnostic criteria of RTT are clinical; mutations in MECP2 are neither diagnostic nor necessary, and a mutation in another gene does not exclude RTT. We attempted to correlate genotype and phenotype to see if there are significant clinical associations. MethodsAll available females diagnosed with RTT in Norway were invited to the study. Parents were interviewed, the girl or woman with RTT examined and medical records reviewed. All diagnoses were revisited according to the current diagnostic criteria and exome-based sequencing analyses were performed in individuals without an identified causative mutation. Participants were categorized according to genotypes and RTT diagnosis. Individuals with RTT with and without mutations in MECP2 were compared. ResultsNinety-one individuals were included. A presumed causative mutation was identified in 86 individuals, of these, mutations in MECP2 in 77 individuals and mutations in SMC1A, SYNGAP1, SCN1A, CDKL5, FOXG1 or chromosome 13q in nine. Seventy-two individuals fulfilled the diagnostic criteria for classic and 12 for atypical RTT. Significant differences in early development, loss of hand use and language, intense eye gaze and the presence of early onset epilepsy were revealed in individuals with RTT according to their MECP2 genotypic status. ConclusionUsing the current diagnostic criteria, genetic and clinical variation in RTT is considerable. Significant differences between individuals with RTT with and without MECP2 mutations indicate that MECP2 is a major determinant for the clinical phenotype in individuals with RTT.

Rett Syndrome: MECP2 gene molecular analysis in Chilean patients

Rett syndrome (RTT) is a progressive neurological disorder characterized by regres sion of psychomotor development in previously healthy girls. Most cases are due to pathogenic va riants in the MECP2 gene which encodes for the methyl CpG-binding protein 2. To des cribe the frequency and type of pathogenic variants in the MECP2 gene in Chilean female patients with clinical diagnosis of RTT. Chilean women with clinical suspicion of RTT were invited to participate in the study. Clinical data were collected through a questionnaire. MECP2 pathogenic variants were analyzed by Sanger sequencing method and Multiplex Ligation-dependent Probe Amplification (MLPA) was used to detect duplications or deletions. The study in cluded 14 patients with suspected RTT, of which eight (57%) patients had pathogenic variants. The other patients remain without molecular diagnosis. Pathogenic variants in MECP2 are present in Chilean patients with RTT. It is likely that there are other genes or diagnoses involved in patients without MECP2 findings. As of this study, molecular diagnosis is available in Chile.

Updates on pathogenesis-related genes and diagnosis and treatment of Rett syndrome

Rett syndrome (RTT) is a devastating neurological disorder that is caused largely by mutations in the X-linked gene MECP2, other two genes associated with RTT are CDKL5 and FOXG1.RTT is one of the most common causes of mental retardation in girls, male cases are rare.Classical features of typical RTT include losing acquired spoken language and hand skills, hand stereotypies, epilepsy and respiratory disorders.The diagnosis of RTT mainly depends on the clinical characteristics.Atpresent, it still lacks atargeted treatment.In this review, we summarize both the gene research, diagnosis and treatmentprogresses of RTT so as to improve the understanding of RTT. Key words: Rett syndrome; Female; Mecp2; Diagnosis; Treatment

Spectrum of MECP2 mutations in Vietnamese patients with RETT syndrome

BackgroundRett syndrome (RTT) is a severe neurodevelopmental disorder in children characterized by a normal neurodevelopmental process in the first 6–18 months followed by a period of motor and vocal deterioration with stereotypic hand movements. Incidence of RTT is mostly due to de novo mutation in the MECP2 gene (methyl-CpG-binding protein 2).MethodsThe study assessed 27 female patients presented with classical RTT phenotype age range from 18 months to 48 months. Specialist carried out the clinical evaluation and diagnosis according to RTT diagnosis criteria. Blood samples from patients were then collected for genomic DNA extraction. We next performed MECP2 gene amplification and sequencing of the whole coding region to screen for mutations.ResultMECP2 mutation was found in 20 patients (74%) including: 2 missense, 4 nonsense, 6 frameshift and 2 deletion mutation. The study identified 14 pathogenic mutations which we found 4 mutation, to our knowledge and extensive search, not priory reported in any mutation database or publication: c.1384-1385DelGT, c.1205insT, c.717delC and c.1132_1207del77. High percentage of C > T (70%) in CpG sites mutation was found.ConclusionOur result reveals a high percentage of C > T mutation in CpG hot spot, which is more prone to modification and more likely to be detected in RTT as a disorder is strictly due to de novo mutations. The study is the first to identify the mutation spectrum of MECP2 gene in Vietnamese patients and also an important step toward better diagnosis and care for RTT patients in Vietnam.

Identification of autism-related MECP2 mutations by whole-exome sequencing and functional validation

BackgroundMethyl-CpG-binding protein-2 (MeCP2) is a critical regulator for neural development. Either loss- or gain-of-function leads to severe neurodevelopmental disorders, such as Rett syndrome (RTT) and autism spectrum disorder (ASD). We set out to screen for MECP2 mutations in patients of ASD and determine whether these autism-related mutations may compromise the proper function of MeCP2.MethodsWhole-exome sequencing was performed to screen MECP2 and other ASD candidate genes for 120 patients diagnosed with ASD. The parents of patients who were identified with MECP2 mutation were selected for further Sanger sequencing. Each patient accomplished the case report form including general information and clinical scales applied to assess their clinical features. Mouse cortical neurons and HEK-293 cells were cultured and transfected with MeCP2 wild-type (WT) or mutant to examine the function of autism-associated MeCP2 mutants. HEK-293 cells were used to examine the expression of MeCP2 mutant constructs with Western blot. Mouse cortical neurons were used to analyze neurites and axon outgrowth by immunofluorescence experiments.ResultsWe identified three missense mutations of MECP2 from three autism patients by whole-exome sequencing: p.P152L (c.455C>T), p.P376S (c.1162C>T), and p.R294X (c.880C>T). Among these mutations, p.P152L and p.R294X were de novo mutations, whereas p.P376S was inherited maternally. The diagnosis of RTT was excluded in all three autism patients. Abnormalities of dendritic and axonal growth were found after autism-related MeCP2 mutants were expressed in mouse cortical neurons; suggesting that autism-related MECP2 mutations impair the proper development of neurons.ConclusionsOur study identified genetic mutations of the MECP2 gene in autism patients, which were previously considered to be associated primarily with RTT. This finding suggests that loss-of-function mutations of MECP2 may also lead to autism spectrum disorders.

The Epilepsies of Rett Syndrome in Indonesia

Objective This study aimed to evaluate various types of sei-zures, EEG findings, and last evolution of epileptic seizures foundin children with Rett Syndrome (RTT).Methods A case series of ten female subjects from Sardjito Hos-pital, Yogyakarta; Cipto Mangunkusumo Hospital, Jakarta; andHasan Sadikin Hospital, Bandung from February 2001-April 2004.Diagnosis of RTT was established using necessary and support-ive criteria by the RTT Diagnostic Criteria Work Group and epi-lepsy was diagnosed according to clinical and EEG findings.Results The age during initial diagnosis of RTT ranged from 2years 6 months - 10 years 2 months (average: 4 years 6 months).The diagnosis of epilepsy, on the other hand, was establishedfrom 2 years - 5 years 10 months (average: 3 years 8 months).All subjects (10/10) had abnormal EEG results. Eight out of tenhad epileptiform discharge; the remaining had slowing backgroundactivity. The average age of initial seizure onset was 18 months.Five were diagnosed as epileptic subjects. Febrile convulsionswere the most common initial seizure. General tonic clonic sei-zure was major type of seizure which manifested in 2 subjects.Conclusion All EEG results showed abnormality, although sei-zure did not appear. Five out of ten subjects experienced epi-lepsy

Neurophysiology versus clinical genetics in Rett syndrome: A multicenter study.

Many studies have attempted to establish the genotype–phenotype correlation in Rett syndrome (RTT). Cardiorespiratory measurements provide robust objective data, to correlate with each of the different clinical phenotypes. It has important implications for the management and treatment of this syndrome. The aim of this study was to correlate the genotype with the quantitative cardiorespiratory data obtained by neurophysiological measurement combined with a clinical severity score. This international multicenter study was conducted in four European countries from 1999 to 2012. The study cohort consisted of a group of 132 well‐defined RTT females aged between 2 and 43 years with extended clinical, molecular, and neurophysiological assessments. Diagnosis of RTT was based on the consensus criteria for RTT and molecular confirmation. Genotype–phenotype analyses of clinical features and cardiorespiratory data were performed after grouping mutations by the same type and localization or having the same putative biological effect on the MeCP2 protein, and subsequently on eight single recurrent mutations. A less severe phenotype was seen in females with CTS, p.R133C, and p.R294X mutations. Autonomic disturbances were present in all females, and not restricted to nor influenced by one specific group or any single recurrent mutation. The objective information from non‐invasive neurophysiological evaluation of the disturbed central autonomic control is of great importance in helping to organize the lifelong care for females with RTT. Further research is needed to provide insights into the pathogenesis of autonomic dysfunction, and to develop evidence‐based management in RTT. © 2016 The Authors. American Journal of Medical Genetics Part A published by Wiley Periodicals, Inc.

Is it possible to diagnose Rett syndrome before classical symptoms become obvious? Review of 24 Danish cases born between 2003 and 2012.

Rett syndrome (RTT) is a neurodevelopmental disorder that affects mainly females; it results in multiple disabilities and carries a risk of medical comorbidities. Early diagnosis is important to help establish the best treatment opportunities and preventive care in order to slow down the progression of symptoms. We wanted to test our hypothesis that it is possible to diagnose RTT before the classical symptoms become obvious. We analysed development and symptoms before and at the time of the RTT diagnosis, as well as the symptoms that triggered MECP2 mutation analysis, in a cohort of girls with RTT born in Denmark between 2003 and 2012. Twenty-four girls were included, and 87.5% of these girls were diagnosed when the classical RTT symptoms were recognized. However, parents were concerned about their daughters between 3 and 58 months prior to the RTT diagnosis, and they felt that the professionals did not share their concern in the beginning. When reviewing medical files and questionnaires, we noted that the majority of girls did have combinations of concerning symptoms such as developmental delay and a collection of subtle signs such as autistic traits, placidity, floppiness with suspicion of muscular or mitochondrial diseases, hair pulling, teeth grinding, development of incontinence and problems with initiating movements. We conclude that many individuals with MECP2 mutation exhibit characteristics that should raise suspicion for RTT, prior to evolution of the core clinical criteria. As RTT is a rare disease, it is of importance to constantly educate clinicians for heightened awareness of RTT.

The Utility of Next-Generation Sequencing in Gene Discovery for Mutation-Negative Patients with Rett Syndrome.

Rett syndrome (RTT) is a rare, severe disorder of neuronal plasticity that predominantly affects girls. Girls with RTT usually appear asymptomatic in the first 6–18 months of life, but gradually develop severe motor, cognitive, and behavioral abnormalities that persist for life. A predominance of neuronal and synaptic dysfunction, with altered excitatory–inhibitory neuronal synaptic transmission and synaptic plasticity, are overarching features of RTT in children and in mouse models. Over 90% of patients with classical RTT have mutations in the X-linked methyl-CpG-binding (MECP2) gene, while other genes, including cyclin-dependent kinase-like 5 (CDKL5), Forkhead box protein G1 (FOXG1), myocyte-specific enhancer factor 2C (MEF2C), and transcription factor 4 (TCF4), have been associated with phenotypes overlapping with RTT. However, there remain a proportion of patients who carry a clinical diagnosis of RTT, but who are mutation negative. In recent years, next-generation sequencing technologies have revolutionized approaches to genetic studies, making whole-exome and even whole-genome sequencing possible strategies for the detection of rare and de novo mutations, aiding the discovery of novel disease genes. Here, we review the recent progress that is emerging in identifying pathogenic variations, specifically from exome sequencing in RTT patients, and emphasize the need for the use of this technology to identify known and new disease genes in RTT patients.

P189 – 2279: Is the regression period in Rett syndrome well defined and easy to recognize?

Objective In order to increase knowledge of regression as a clue to diagnose Rett syndrome (RTT), we want to investigate if the regression period (RP) is well defined and easy to recognize. Methods Medical records (including questionnaires and interviews) were reviewed concerning the RP in children with clinical Rett syndrome and a MECP2 mutation referred to the nation-wide Centre for Rett syndrome in Denmark in the years 2012–2014. Results Ten girls with RTT (8 typical/2 atypical) and a MECP2 mutation aged 1.7–5.3 years (mean 3.3 years; median 2.8 years) were referred to the centre and evaluated within 13–152 days (mean 58.3 days; median 41.5 days). Seven of the girls were post regression at this first evaluation. In the other 3 cases it was difficult to conclude but time showed that 2 girls were still in regression at the first visit. The girls were in RP in the range of about 4–35 months (mean 14.8 mo; median 12 mo). Before the RTT diagnosis 5 of the girls were referred to psychiatric evaluation at a time that turned out to be in the RP. One of these girls and 3 others had a muscular biopsy before (2), under (1) or after (1) an unrecognized RP. One girl had severe symptoms of epilepsy and adverse reactions to medication in RP. In 6 cases the RP along with other symptoms as handstereotypies led to suspicion of RTT. Five of the girls were diagnosed in the RP and the other 5 after the RP. Conclusion In most of our cases, RP was not well defined or easily recognized. It might be overlooked because of its long and slow progression as well as co-morbidities like hypotonia or epilepsy. We conclude that more information regarding regression in RTT is needed to facilitate early diagnosis, counselling and treatment.