International workshop: what is needed to ensure outcome measures for Rett syndrome are fit-for-purpose for clinical trials? June 7, 2023, Nashville, USA.

Introduction: The clinical, research and advocacy communities for Rett syndrome are striving to achieve clinical trial readiness, including having fit-for-purpose clinical outcome assessments. This study aimed to (1) describe psychometric properties of clinical outcome assessment for Rett syndrome and (2) identify what is needed to ensure that fit-for-purpose clinical outcome assessments are available for clinical trials.

Methods: Clinical outcome assessments for the top 10 priority domains identified in the Voice of the Patient Report for Rett syndrome were compiled and available psychometric data were extracted.

Structural variant allelic heterogeneity in MECP2 duplication syndrome provides insight into clinical severity and variability of disease expression.

Background: MECP2 Duplication Syndrome, also known as X-linked intellectual developmental disorder Lubs type (MRXSL; MIM: 300260), is a neurodevelopmental disorder caused by copy number gains spanning MECP2. Despite varying genomic rearrangement structures, including duplications and triplications, and a wide range of duplication sizes, no clear correlation exists between DNA rearrangement and clinical features. We had previously demonstrated that up to 38% of MRXSL families are characterized by complex genomic rearrangements (CGRs) of intermediate complexity (2 ≤ copy number variant breakpoints < 5), yet the impact of these genomic structures on regulation of gene expression and phenotypic manifestations have not been investigated.

Efficient non-viral immune cell engineering using circular single-stranded DNA-mediated genomic integration.

The use of adeno-associated viruses (AAVs) as donors for homology-directed repair (HDR)-mediated genome engineering is limited by safety issues, manufacturing constraints and restricted packaging limits. Non-viral targeted genetic knock-ins rely primarily on double-stranded DNA (dsDNA) and linear single-stranded DNA (lssDNA) donors. dsDNA is known to have low efficiency and high cytotoxicity, while lssDNA is challenging for scaled manufacture.

Modeling antisense oligonucleotide therapy in MECP2 duplication syndrome human iPSC-derived neurons reveals gene expression programs responsive to MeCP2 levels.

Genomic copy-number variations (CNVs) that can cause neurodevelopmental disorders often encompass many genes, which complicates our understanding of how individual genes within a CNV contribute to pathology. MECP2 duplication syndrome (MDS or MRXSL in OMIM; OMIM#300260) is one such CNV disorder caused by duplications spanning methyl CpG-binding protein 2 (MECP2) and other genes on Xq28. Using an antisense oligonucleotide (ASO) to normalize MECP2 dosage is sufficient to rescue abnormal neurological phenotypes in mouse models overexpressing MECP2 alone, implicating the importance of increased MECP2 dosage within CNVs of Xq28.

Deletions in the CDKL5 5' untranslated region lead to CDKL5 deficiency disorder.

Pathogenic variants in the cyclin-dependent kinase-like 5 (CDKL5) gene are associated with CDKL5 deficiency disorder (CDD), a severe X-linked developmental and epileptic encephalopathy. Deletions affecting the 5' untranslated region (UTR) of CDKL5, which involve the noncoding exon 1 and/or alternatively spliced first exons (exons 1a-e), are uncommonly reported. We describe genetic and phenotypic characteristics for 15 individuals with CDKL5 partial gene deletions affecting the 5' UTR.

Clinical Features and Disease Progression in Older Individuals with Rett Syndrome.

Although long-term survival in Rett syndrome (RTT) has been observed, limited information on older people with RTT exists. We hypothesized that increased longevity in RTT would be associated with genetic variants in associated with milder severity, and that clinical features would not be static in older individuals. To address these hypotheses, we compared the distribution of variants and clinical severity between younger individuals with Classic RTT (under 30 years old) and older individuals (over 30 years old).

Psychometric evaluation of clinician- and caregiver-reported clinical severity assessments for individuals with CDKL5 deficiency disorder.

Objective: The CDKL5 Clinical Severity Assessment (CCSA) is a comprehensive, content-validated measurement tool capturing the diverse challenges of cyclin-dependent kinase-like 5 (CDKL5) deficiency disorder (CDD), a genetically caused developmental epileptic encephalopathy (DEE). The CCSA is divided into clinician-reported (CCSA-Clinician) and caregiver-reported (CCSA-Caregiver) assessments. The aim of this study was to evaluate the factor structure of these measures through confirmatory factor analysis (CFA) and evaluate their validity and reliability.

Modification of a parent-report sleep scale for individuals with CDKL5 deficiency disorder: a psychometric study.

Study Objectives: Sleep difficulties are common in CDKL5 deficiency disorder, a developmental and epileptic encephalopathy. This study evaluated the factor structure of the Disorders of Initiating and Maintaining Sleep (DIMS), Disorders of Excessive Somnolence (DOES), and Sleep Breathing Disorders domains of the Sleep Disturbance Scale for Children for CDKL5 deficiency disorder.

Methods: A cross-sectional psychometric study design was used.

Sensory experiences questionnaire unravels differences in sensory profiles between MECP2-related disorders.

The methyl CpG-binding protein-2 (MECP2) gene is located on the Xq28 region. Loss of function mutations or increased copies of MECP2 result in Rett syndrome (RTT) and MECP2 duplication syndrome (MDS), respectively. Individuals with both disorders exhibit overlapping autism symptoms, yet few studies have dissected the differences between these gene dosage sensitive disorders.

Development and validation of parent-reported gastrointestinal health scale in MECP2 duplication syndrome.

Background/aims: We aimed to develop a validated patient-reported Gastrointestinal Health Scale (GHS) specific to MECP2 Duplication Syndrome (MDS) to be used in clinical trials.

Methods: MDS parents completed a Gastrointestinal Health Questionnaire (GHQ) to investigate the most relevant and important items associated with gastrointestinal problems in MECP2-related disorders. Item reduction was executed according to EORTC guidelines.

Generation of five induced pluripotent stem cell lines from patients with MECP2 Duplication Syndrome.

MECP2 Duplication Syndrome (MDS) is a rare, severe neurodevelopmental disorder arising from duplications in the Xq28 region containing the MECP2 gene that predominantly affects males. We generated five human induced pluripotent stem cell (iPSC) lines from the fibroblasts of individuals carrying between 0.355 and 11.

Top caregiver concerns in Rett syndrome and related disorders: data from the US natural history study.

Objective: Recent advances in the understanding of neurodevelopmental disorders such as Rett syndrome (RTT) have enabled the discovery of novel therapeutic approaches that require formal clinical evaluation of efficacy. Clinical trial success depends on outcome measures that assess clinical features that are most impactful for affected individuals. To determine the top concerns in RTT and RTT-related disorders we asked caregivers to list the top caregiver concerns to guide the development and selection of appropriate clinical trial outcome measures for these disorders.

The development, content and response process validation of a caregiver-reported severity measure for CDKL5 deficiency disorder.

Background: CDKL5 Deficiency Disorder (CDD) is a severe X-linked developmental and epileptic encephalopathy. Existing developmental outcome measures have floor effects and cannot capture incremental changes in symptoms. We modified the caregiver portion of a CDD clinical severity assessment (CCSA) and assessed content and response-process validity.

Exploring gastrointestinal health in MECP2 duplication syndrome.

Background: MECP2 duplication syndrome (MDS) is a rare neurogenetic syndrome caused by duplications of MECP2 at the Xq28 region. Although constipation and gastrointestinal reflux are reported in MDS, a comprehensive characterization of gastrointestinal health has not been fully explored.

Methods: We conducted a parent survey to explore the characteristics of gastrointestinal health in individuals with MDS using a secure online registry and compared differences in gastrointestinal symptoms between individuals with MDS and those with Rett syndrome (RTT).

Epileptic spasms in CDKL5 deficiency disorder: Delayed treatment and poor response to first-line therapies.

Objective: We aimed to assess the treatment response of infantile-onset epileptic spasms (ES) in CDKL5 deficiency disorder (CDD) vs other etiologies.

Methods: We evaluated patients with ES from the CDKL5 Centers of Excellence and the National Infantile Spasms Consortium (NISC), with onset from 2 months to 2 years, treated with adrenocorticotropic hormone (ACTH), oral corticosteroids, vigabatrin, and/or the ketogenic diet. We excluded children with tuberous sclerosis complex, trisomy 21, or unknown etiology with normal development because of known differential treatment responses.

Top Caregiver Concerns in Rett syndrome and related disorders: data from the US Natural History Study.

Objective: Recent advances in the understanding of neurodevelopmental disorders such as Rett syndrome (RTT) has enabled development of novel therapeutic approaches that are currently undergoing clinical evaluation or are proposed to move into clinical development. Clinical trial success depends on outcome measures that assess clinical features that are most impactful for affected individuals. To determine the top concerns in RTT and RTT-related disorders we asked caregivers to list the top clinical concerns in order to gain information to guide the development and selection of outcome measures for future clinical trials.

Resilience, and positive parenting in parents of children with syndromic autism and intellectual disability. Evidence from the impact of the COVID-19 pandemic on family's quality of life and parent-child relationships.

Family quality of life (FQoL) outcomes collected during the first year of COVID-19 has been combined with 2018 data to estimate the outbreak's impact on parental outcomes on a sample of 230 families with syndromic autistic children and those with intellectual disabilities (IDs). Despite challenges imposed by the COVID-19 outbreak, our study found that FQoL outcomes reported by participating parents during the first year of COVID-19 appears to be similar to ratings from a prepandemic study of families with the same conditions. Parents of children in our sample generally displayed a stable functioning trajectory as measured by the validated FQoL instrument.

Assessing the Burden on Caregivers of MECP2 Duplication Syndrome.

Background: MECP2 duplication syndrome (MDS) is a rare neurogenetic disorder characterized by severe neurodevelopmental disorder, refractory epilepsy, recurrent infections, and functional gastrointestinal problems. Because of the significant clinical problems and lifelong disability of children with this disorder we hypothesized that the burden on parents/caregivers of these children is significant. However, there are no reports of the impact on caregivers of individuals with MDS.

Exploring the characteristics and most bothersome symptoms in MECP2 duplication syndrome to pave the path toward developing parent-oriented outcome measures.

Background: MECP2 Duplication Syndrome (MDS), resulting from the duplication of Xq28 region, including MECP2, is a rare disorder with a nascent understanding in clinical features and severity. Studies using antisense oligonucleotides revealed a broad phenotypic rescue in transgenic mice. With human clinical trials on the horizon, there is a need to develop clinical outcome measures for MDS.

COVID-19 Induced Environments, Health-Related Quality of Life Outcomes and Problematic Behaviors: Evidence from Children with Syndromic Autism Spectrum Disorders.

Between July 2020 and January 2021, 230 principal caregivers completed a questionnaire to measure proxy-assessed health-related quality of life outcomes (HRQoL), behavioral outcomes in children with syndromic autism spectrum disorders and COVID-19 induced changes to lifestyle and environments. HRQoL and behavioral outcomes reported earlier during the pandemic were generally worse compared to those reported later. COVID-19 induced reduction to a caregiver's mental health appointments, and hours spent watching TV were associated with decreases in HRQoL and increased the likelihood of problematic behaviors.

Current neurologic treatment and emerging therapies in CDKL5 deficiency disorder.

Background: CDKL5 deficiency disorder (CDD) is associated with refractory infantile onset epilepsy, global developmental delay, and variable features that include sleep, behavioral disturbances, and movement disorders. Current treatment is primarily symptom-based and informed by experience in caring for this population.

Methods: We describe medication and non-medication approaches to treatment of epilepsy and additional key neurologic symptoms (sleep disturbances, behavioral issues, movement disorders, and swallowing dysfunction) in a cohort of 177 individuals meeting criteria for CDD, 154 evaluated at 4 CDKL5 Centers of Excellence in the USA and 40 identified through the NIH Natural History Study of Rett and Related Disorders.

Content Validation of Clinician-Reported Items for a Severity Measure for CDKL5 Deficiency Disorder.

CDKL5 deficiency disorder (CDD) results in early-onset seizures and severe developmental impairments. A CDD clinical severity assessment (CCSA) was previously developed with clinician and parent-report items to capture information on a range of domains. Consistent with US Food and Drug Administration (FDA) guidelines, content validation is the first step in evaluating the psychometric properties of an outcome measure.

Inhibition of Elevated Ras-MAPK Signaling Normalizes Enhanced Motor Learning and Excessive Clustered Dendritic Spine Stabilization in the MECP2-Duplication Syndrome Mouse Model of Autism.

The inflexible repetitive behaviors and "insistence on sameness" seen in autism imply a defect in neural processes controlling the balance between stability and plasticity of synaptic connections in the brain. It has been proposed that abnormalities in the Ras-ERK/MAPK pathway, a key plasticity-related cell signaling pathway known to drive consolidation of clustered synaptic connections, underlie altered learning phenotypes in autism. However, a link between altered Ras-ERK signaling and clustered dendritic spine plasticity has yet to be explored in an autism animal model The formation and stabilization of dendritic spine clusters is abnormally increased in the MECP2-duplication syndrome mouse model of syndromic autism, suggesting that ERK signaling may be increased.