Changing the perspective on early development of Rett syndrome

Shared Environment - Different Genes: Speech-Language Development in a Pair of Dizygotic Twins with and Without MECP2 Mutation

This retrospective study compared the speech-language development of a pair of dizygotic twin girls during the first 2 years of life: one with typical development (Twin A) and one with atypical development (Twin B), who was later diagnosed with Rett syndrome (RTT). Audio snippets were extracted from home videos, with nearly equal representation from each child. The audio analysis focused on articulatory complexity, voice characteristics, and linguistic variability. Despite sharing the same social-communicative environment, the twins' speech-language development diverged. From the first to second year of life, articulatory complexity and variability increased in the typically developing Twin A. In contrast, Twin B produced a high number of vocalizations in the 7th month, including canonical sounds with substantial variability. However, her vocalization quantity, complexity, and variability subsequently decreased, resulting in only sporadically discernable canonical vocalizations during her second year. This developmental trajectory points to very early stagnation and regression in Twin B, occurring earlier than typically observed. While Twin B displayed a range of typical vocalization features, deviations in the density and distribution of inspiratory and high-pitched vocalizations during the first year further suggest early speech-language abnormalities in RTT, preceding frank developmental stagnation and regression. As the study relied on limited retrospective data, the findings should be interpreted with caution, and further investigation is needed. Nevertheless, this twin study provides a unique perspective that deepens our understanding of early speech-language developmental profiles in RTT, especially in light of the intertwinement of genetic, individual, and contextual factors.

To speak may draw on epigenetic writing and reading: Unravelling the complexity of speech and language outcomes across chromatin-related neurodevelopmental disorders

Speech and language development are complex neurodevelopmental processes that are incompletely understood, yet current evidence suggests that speech and language disorders are prominent in those with disorders of chromatin regulation. This review aimed to unravel what is known about speech and language outcomes for individuals with chromatin-related neurodevelopmental disorders. A systematic literature search following PRISMA guidelines was conducted on 70 chromatin genes, to identify reports of speech/language outcomes across studies, including clinical reports, formal subjective measures, and standardised/objective measures. 3932 studies were identified and screened and 112 were systematically reviewed. Communication impairment was core across chromatin disorders, and specifically, chromatin writers and readers appear to play an important role in motor speech development. Identification of these relationships is important because chromatin disorders show promise as therapeutic targets due to the capacity for epigenetic modification. Further research is required using standardised and formal assessments to understand the nuanced speech/language profiles associated with variants in each gene, and the influence of chromatin dysregulation on the neurobiology of speech and language development.

Learning about neurodiversity from parents - Auditory gestalt perception of prelinguistic vocalisations

BACKGROUND

Infants with Rett syndrome (RTT) may have subtle anomalies in their prelinguistic vocalisations but the detection of these is difficult, since their conspicuous vocalisations are often interspersed with inconspicuous ones.

AIMS AND METHODS

Extending a previous study with predominantly non-parents, the present study sampled parents of children with RTT and aimed to examine their gestalt perception of prelinguistic vocalisations.

METHODS AND PROCEDURE

Parents (n = 76) of female children with RTT listened to vocalisation recordings from RTT and typically developing (TD) infants, including an inconspicuous vocalisation from a RTT girl. For each recording, parents indicated if the vocalisation was produced by a RTT or a TD child.

RESULTS

Overall correct to incorrect identification rate was 2:1, which was comparable to that of the previous study. Intriguingly, parents of RTT children seemed to be sensitive to features characterising the vocalisations of RTT infants, which has especially influenced their perception of the inconspicuous vocalisation from a RTT girl.

CONCLUSIONS AND IMPLICATIONS

These results invite further research on the potential characterising differences between vocalisations from TD infants and infants with divergent neurodevelopment.

Psychometric Values of a New Scale: The Rett Syndrome Fear of Movement Scale (RSFMS)

(1) Background: One of the characteristics associated with Rett syndrome (RTT) is a fear of movement (FOM). Despite the grave consequences on health, function, and the caregiver's burden associated with bradykinesia accompanying FOM, there is no specific FOM assessment tool for RTT. (2) Objective: To construct and assess the psychometric values of a scale evaluating FOM in RTT (Rett syndrome fear of movement scale-RSFMS). (3) Methods: Twenty-five girls aged 5-33, including a research group (N = 12 individuals with RTT) and control group (N = 13 typically developing girls at equivalent ages). The Pain and Discomfort Scale (PADS) and Facial Action Coding System (FACS) assessed the participants' behavior and facial expressions in rest and movement situations. (4) Results: Significant behavioral differences were recorded in these rest and movement situations within the research groups using the RSFMS (p = 0.003), FACS (p = 0.002) and PADS (p = 0.002). No differences in reactions were found within the control group. The new scale, RSFMS, was found to show a high inter- and intra-rater reliability (r = 0.993, p < 0.001; r = 0.958, p < 0.001; respectively), good internal consistency (α = 0.77), and high accuracy (94.4%). (5) Conclusions: The new scale for measuring FOM in RTT, the RSFMS, was validated using the FACS and PADS. The RSFMS was found to be a tool that holds excellent psychometric values. The new scale can help clinicians working with individuals with RTT to plan appropriate management strategies for this population.

A comprehensive longitudinal study of magnetic resonance imaging identifies novel features of the Mecp2 deficient mouse brain

Rett syndrome (RTT) is a X-linked neurodevelopmental disorder which represents the leading cause of severe incurable intellectual disability in females worldwide. The vast majority of RTT cases are caused by mutations in the X-linked MECP2 gene, and preclinical studies on RTT largely benefit from the use of mouse models of Mecp2, which present a broad spectrum of symptoms phenocopying those manifested by RTT patients. Neurons represent the core targets of the pathology; however, neuroanatomical abnormalities that regionally characterize the Mecp2 deficient mammalian brain remain ill-defined. Neuroimaging techniques, such as MRI and MRS, represent a key approach for assessing in vivo anatomic and metabolic changes in brain. Being non-invasive, these analyses also permit to investigate how the disease progresses over time through longitudinal studies. To foster the biological comprehension of RTT and identify useful biomarkers, we have performed a thorough in vivo longitudinal study of MRI and MRS in Mecp2 deficient mouse brains. Analyses were performed on both genders of two different mouse models of RTT, using an automatic atlas-based segmentation tool that permitted to obtain a detailed and unbiased description of the whole RTT mouse brain. We found that the most robust alteration of the RTT brain consists in an overall reduction of the brain volume. Accordingly, Mecp2 deficiency generally delays brain growth, eventually leading, in heterozygous older animals, to stagnation and/or contraction. Most but not all brain regions participate in the observed deficiency in brain size; similarly, the volumetric defect progresses diversely in different brain areas also depending on the specific Mecp2 genetic lesion and gender. Interestingly, in some regions volumetric defects anticipate overt symptoms, possibly revealing where the pathology originates and providing a useful biomarker for assessing drug efficacy in pre-clinical studies.

Inter-rater reliability in classification of canonical babbling status based on canonical babbling ratio in infants with isolated cleft palate randomised to Timing of Primary Surgery for Cleft Palate (TOPS)

Canonical babbling (CB) is commonly defined as present when at least 15% of all syllables produced are canonical, in other words a canonical babbling ratio (CBR) ≥0.15. However, there is limited knowledge about inter-rater reliability in classification of CB status based on CBR and inter-rater differences in assessment of CBR. We investigated inter-rater reliability of experienced Speech Language Therapists (SLTs) on: classification of CB status based on CBR ≥ 0.15, CBRs and the total number of syllables per infant used to calculate CBR.Each infant (n = 484) was video-recorded at a clinical site in play interaction with their parent as part of the randomised controlled trial Timing of Primary Surgery for Cleft Palate. Each recording was subsequently assessed by three independent SLTs, from a pool of 29 SLTs. They assessed the recordings in real time.The three assessing SLTs agreed in classification of CB status in 423 (87.4%) infants, with higher complete agreement for canonical (91%; 326/358) than non-canonical (77%; 97/126). The average difference in CBR and total number of syllables identified between the SLT assessments of each infant was 0.12 and 95, respectively.This study provided new evidence that one trained SLT can reliably classify CB status (CBR ≥ 0.15) in real time when there is clear distinction between the observed CBR and the boundary (0.15); however, when the observed CBR approaches the boundary multiple SLT assessments are beneficial. Thus, we recommend to include assessment of inter-rater reliability, if the purpose is to compare CBR and total syllable count across infants or studies.Trial registration number here: www.clinicaltrials.gov, identifier NCT00993551.

Emerging Verbal Functions in Early Infancy: Lessons from Observational and Computational Approaches on Typical Development and Neurodevelopmental Disorders

OBJECTIVES

Research on typically developing (TD) children and those with neurodevelopmental disorders and genetic syndromes was targeted. Specifically, studies on autism spectrum disorder, Down syndrome, Rett syndrome, fragile X syndrome, cerebral palsy, Angelman syndrome, tuberous sclerosis complex, Williams-Beuren syndrome, Cri-du-chat syndrome, Prader-Willi syndrome, and West syndrome were searched. The objectives are to review observational and computational studies on the emergence of (pre-)babbling vocalisations and outline findings on acoustic characteristics of early verbal functions.

METHODS

A comprehensive review of the literature was performed including observational and computational studies focusing on spontaneous infant vocalisations at the pre-babbling age of TD children, individuals with genetic or neurodevelopmental disorders.

RESULTS

While there is substantial knowledge about early vocal development in TD infants, the pre-babbling phase in infants with neurodevelopmental and genetic syndromes is scarcely scrutinised. Related approaches, paradigms, and definitions vary substantially and insights into the onset and characteristics of early verbal functions in most above-mentioned disorders are missing. Most studies focused on acoustic low-level descriptors (e.g. fundamental frequency) which bore limited clinical relevance. This calls for computational approaches to analyse features of infant typical and atypical verbal development.

CONCLUSIONS

Pre-babbling vocalisations as precursor for future speech-language functions may reveal valuable signs for identifying infants at risk for atypical development. Observational studies should be complemented by computational approaches to enable in-depth understanding of the developing speech-language functions. By disentangling features of typical and atypical early verbal development, computational approaches may support clinical screening and evaluation.

Automatic vocalisation-based detection of fragile X syndrome and Rett syndrome

Fragile X syndrome (FXS) and Rett syndrome (RTT) are developmental disorders currently not diagnosed before toddlerhood. Even though speech-language deficits are among the key symptoms of both conditions, little is known about infant vocalisation acoustics for an automatic earlier identification of affected individuals. To bridge this gap, we applied intelligent audio analysis methodology to a compact dataset of 4454 home-recorded vocalisations of 3 individuals with FXS and 3 individuals with RTT aged 6 to 11 months, as well as 6 age- and gender-matched typically developing controls (TD). On the basis of a standardised set of 88 acoustic features, we trained linear kernel support vector machines to evaluate the feasibility of automatic classification of (a) FXS vs TD, (b) RTT vs TD, (c) atypical development (FXS+RTT) vs TD, and (d) FXS vs RTT vs TD. In paradigms (a)-(c), all infants were correctly classified; in paradigm (d), 9 of 12 were so. Spectral/cepstral and energy-related features were most relevant for classification across all paradigms. Despite the small sample size, this study reveals new insights into early vocalisation characteristics in FXS and RTT, and provides technical underpinnings for a future earlier identification of affected individuals, enabling earlier intervention and family counselling.

Infants later diagnosed with autism have lower canonical babbling ratios in the first year of life

BACKGROUND

Canonical babbling-producing syllables with a mature consonant, full vowel, and smooth transition-is an important developmental milestone that typically occurs in the first year of life. Some studies indicate delayed or reduced canonical babbling in infants at high familial likelihood for autism spectrum disorder (ASD) or who later receive an ASD diagnosis, but evidence is mixed. More refined characterization of babbling in the first year of life in infants with high likelihood for ASD is needed.

METHODS

Vocalizations produced at 6 and 12 months by infants (n = 267) taking part in a longitudinal study were coded for canonical and non-canonical syllables. Infants were categorized as low familial likelihood (LL), high familial likelihood diagnosed with ASD at 24 months (HL-ASD) or not diagnosed (HL-Neg). Language delay was assessed based on 24-month expressive and receptive language scores. Canonical babble ratio (CBR) was calculated by dividing the number of canonical syllables by the number of total syllables. Generalized linear (mixed) models were used to assess the relationship between group membership and CBR, controlling for site, sex, and maternal education. Logistic regression was used to assess whether canonical babbling ratios at 6 and 12 months predict 24-month diagnostic outcome.

RESULTS

No diagnostic group differences in CBR were detected at 6 months, but HL-ASD infants produced significantly lower CBR than both the HL-Neg and LL groups at 12 months. HL-Neg infants with language delay also showed reduced CBR at 12 months. Neither 6- nor 12-month CBR was significant predictors of 24-month diagnostic outcome (ASD versus no ASD) in logistic regression.

LIMITATIONS

Small numbers of vocalizations produced by infants at 6 months may limit the reliability of CBR estimates. It is not known if results generalize to infants who are not at high familial likelihood, or infants from more diverse racial and socioeconomic backgrounds.

CONCLUSIONS

Lower canonical babbling ratios are apparent by the end of the first year of life in ASD regardless of later language delay, but are also observed for infants with later language delay without ASD. Canonical babbling may lack specificity as an early marker when used on its own.

Vocalisation Repertoire at the End of the First Year of Life: An Exploratory Comparison of Rett Syndrome and Typical Development

Rett syndrome (RTT) is a rare, late detected developmental disorder associated with severe deficits in the speech-language domain. Despite a few reports about atypicalities in the speech-language development of infants and toddlers with RTT, a detailed analysis of the pre-linguistic vocalisation repertoire of infants with RTT is yet missing. Based on home video recordings, we analysed the vocalisations between 9 and 11 months of age of three female infants with typical RTT and compared them to three age-matched typically developing (TD) female controls. The video material of the infants had a total duration of 424 min with 1655 infant vocalisations. For each month, we (1) calculated the infants' canonical babbling ratios with CBRUTTER, i.e., the ratio of number of utterances containing canonical syllables to total number of utterances, and (2) classified their pre-linguistic vocalisations in three non-canonical and four canonical vocalisation subtypes. All infants achieved the milestone of canonical babbling at 9 months of age according to their canonical babbling ratios, i.e. CBRUTTER ≥ 0.15. We revealed overall lower CBRsUTTER and a lower proportion of canonical pre-linguistic vocalisations consisting of well-formed sounds that could serve as parts of target-language words for the RTT group compared to the TD group. Further studies with more data from individuals with RTT are needed to study the atypicalities in the pre-linguistic vocalisation repertoire which may portend the later deficits in spoken language that are characteristic features of RTT.

Excitation and Inhibition Imbalance in Rett Syndrome

A loss of the excitation/inhibition (E/I) balance in the neural circuit has emerged as a common neuropathological feature in many neurodevelopmental disorders. Rett syndrome (RTT), a prevalent neurodevelopmental disorder that affects 1:10,000-15,000 women globally, is caused by loss-of-function mutations in the Methyl-CpG-binding Protein-2 (Mecp2) gene. E/I imbalance is recognized as the leading cellular and synaptic hallmark that is fundamental to diverse RTT neurological symptoms, including stereotypic hand movements, impaired motor coordination, breathing irregularities, seizures, and learning/memory dysfunctions. E/I balance in RTT is not homogeneously altered but demonstrates brain region and cell type specificity instead. In this review, I elaborate on the current understanding of the loss of E/I balance in a range of brain areas at molecular and cellular levels. I further describe how the underlying cellular mechanisms contribute to the disturbance of the proper E/I ratio. Last, I discuss current pharmacologic innervations for RTT and their role in modifying the E/I balance.

Design and outcome measures of LAVENDER, a phase 3 study of trofinetide for Rett syndrome

INTRODUCTION

Rett syndrome (RTT) is a debilitating neurodevelopmental disorder with no approved treatments. Trofinetide is a synthetic analog of glycine-proline-glutamate, the N-terminal tripeptide of insulin-like growth factor 1. In a phase 2, placebo-controlled trial in 82 females with RTT aged 5-15 years, a significant (p ≤ 0.042) improvement over placebo was observed with the highest trofinetide dose (200 mg/kg twice daily [BID]) on three measures: Rett Syndrome Behavior Questionnaire (RSBQ), Clinical Global Impression-Improvement (CGI-I), and RTT-Clinician Domain Specific Concerns-Visual Analog Scale (RTT-DSC-VAS). Trofinetide was well tolerated at all doses (50, 100, and 200 mg/kg BID). A phase 3 trial utilizing disease-specific and novel scales was designed to investigate the efficacy and safety of trofinetide in girls and women with RTT.

METHODS

This 12-week, double-blind, randomized, placebo-controlled study (LAVENDER; NCT04181723) will evaluate trofinetide in 187 females, aged 5-20 years, with RTT. Co-primary endpoints are the RSBQ and CGI-I scales. Clinical domains of the CGI-I include communication, ambulation, hand use, seizures, attentiveness, and social (eye contact) and autonomic (breathing) aspects. Secondary endpoints will leverage four novel RTT-specific clinician ratings (derived from the RTT-DSC-VAS) of hand function, ambulation, ability to communicate, and verbal communication, and existing scales, to evaluate other core symptoms of RTT, quality of life and caregiver burden. A 40-week, open-label extension study will follow.

DISCUSSION

This study was designed using disease-specific scales optimized to demonstrate changes in core symptoms of RTT and may provide the first phase 3 data demonstrating drug efficacy in individuals with RTT.

TRIAL REGISTRATION

Clinicaltrials.govNCT04181723.

The enhancement of activity rescues the establishment of Mecp2 null neuronal phenotypes

MECP2 mutations cause Rett syndrome (RTT), a severe and progressive neurodevelopmental disorder mainly affecting females. Although RTT patients exhibit delayed onset of symptoms, several evidences demonstrate that MeCP2 deficiency alters early development of the brain. Indeed, during early maturation, Mecp2 null cortical neurons display widespread transcriptional changes, reduced activity, and defective morphology. It has been proposed that during brain development these elements are linked in a feed-forward cycle where neuronal activity drives transcriptional and morphological changes that further increase network maturity. We hypothesized that the enhancement of neuronal activity during early maturation might prevent the onset of RTT-typical molecular and cellular phenotypes. Accordingly, we show that the enhancement of excitability, obtained by adding to neuronal cultures Ampakine CX546, rescues transcription of several genes, neuronal morphology, and responsiveness to stimuli. Greater effects are achieved in response to earlier treatments. In vivo, short and early administration of CX546 to Mecp2 null mice prolongs lifespan, delays the disease progression, and rescues motor abilities and spatial memory, thus confirming the value for RTT of an early restoration of neuronal activity.

Früherkennung von Entwicklungsstörungen: Kanonisches Lallen (k)‌ein diagnostischer Marker‍(!)?

Zusammenfassung. Theoretischer Hintergrund: Forschungsergebnisse zum frühen Spracherwerb bei Kindern mit spät erkannten Entwicklungsstörungen sind inkonsistent und angesichts unterschiedlicher Forschungsparadigmen und Definitionen nur bedingt vergleichbar. Fragestellung: Ziel dieser Übersichtsarbeit ist es, das Potenzial früher verbaler Fähigkeiten, vor allem des kanonischen Lallens, als Marker zur Früherkennung von Autismus-Spektrum-Störung, Rett-Syndrom und Fragilem-X-Syndrom zu beschreiben. Methode: Übersichtsarbeit über retrospektive und prospektive Studien zu frühen verbalen Fähigkeiten in der Prodromalphase dieser Störungsbilder. Ergebnisse: Einige Kinder mit spät erkannten Entwicklungsstörungen erwerben das kanonische Lallen nach dem kritischen Zeitfenster von 6 bis 10 Monaten und/oder haben oft qualitative Veränderungen in ihren Lautäußerungen. Diskussion und Schlussfolgerung: Eine abweichende Entwicklung des kanonischen Lallens kann auf spätere atypische Entwicklung hinweisen. Als funktioneller Marker für die spezifische Früherkennung von Entwicklungsstörungen scheint dieser Erwerbsmeilenstein jedoch nicht geeignet. Linguistische und signalbasierte Detailanalysen frühkindlicher Vokalisationen könnten zukünftig einen entscheidenden Beitrag hierzu leisten.

Die Bedeutung fötaler und neonataler Motorik für die kindliche Entwicklung und die Früherkennung von Entwicklungsstörungen

Zusammenfassung. Theoretischer Hintergrund: Die von Central Pattern Generators (CPGs) generierten Bewegungen des Neugeborenen und jungen Säuglings haben eine lange pränatale Vorgeschichte. Fragestellung: Welche Bedeutung hat die Analyse der CPG-Aktivität, besonders der General Movements (GMs) in der entwicklungsneurologischen Diagnostik? Methode: Unsere Übersichtsarbeit bezieht sich auf Prechtl’s General Movement Assessment (GMA), das ab dem Frühgeborenenalter bis zum Ende des 5. Monats nach einer Termingeburt anwendbar ist. Ergebnisse: Das GMA ermöglicht die Vorhersage einer Zerebralparese mit einer Sensitivität von 98 % und einer Spezifität von 91 %. Abnormale cramped-synchronized GMs sind ein früher Marker für spastische Zerebralparesen. Das Fehlen von Fidgety Movements (im 3.–5. Monat) weist auf alle Formen der Zerebralparese hin und kann auch bei bestimmten genetischen Erkrankungen auftreten. Zwei von drei Säuglingen mit einer späteren Diagnose Autismus haben atypische GMs und fallen vor allem durch ihre Monotonie in den Bewegungen auf. Diskussion und Schlussfolgerung: Mittels GMA lassen sich mit großer Treffsicherheit typische Entwicklungsverläufe vorhersagen oder aber ein Risiko für einen atypischen Verlauf erkennen und somit frühzeitige Interventionen einleiten.

Overshooting Subcellular Redox-Responses in Rett-Mouse Hippocampus during Neurotransmitter Stimulation

Rett syndrome (RTT) is a neurodevelopmental disorder associated with disturbed neuronal responsiveness and impaired neuronal network function. Furthermore, mitochondrial alterations and a weakened cellular redox-homeostasis are considered part of the complex pathogenesis. So far, overshooting redox-responses of MeCP2-deficient neurons were observed during oxidant-mediated stress, hypoxia and mitochondrial inhibition. To further clarify the relevance of the fragile redox-balance for the neuronal (dys)function in RTT, we addressed more physiological stimuli and quantified the subcellular redox responses to neurotransmitter-stimulation. The roGFP redox sensor was expressed in either the cytosol or the mitochondrial matrix of cultured mouse hippocampal neurons, and the responses to transient stimulation by glutamate, serotonin, dopamine and norepinephrine were characterized. Each neurotransmitter evoked more intense oxidizing responses in the cytosol of MeCP2-deficient than in wildtype neurons. In the mitochondrial matrix the neurotransmitter-evoked oxidizing changes were more moderate and more uniform among genotypes. This identifies the cytosol as an important reactive oxygen species (ROS) source and as less stably redox buffered. Fura-2 imaging and extracellular Ca²⁺ withdrawal confirmed cytosolic Ca²⁺ transients as a contributing factor of neurotransmitter-induced redox responses and their potentiation in the cytosol of MeCP2-deficient neurons. Chemical uncoupling demonstrated the involvement of mitochondria. Nevertheless, cytosolic NADPH- and xanthine oxidases interact to play the leading role in the neurotransmitter-mediated oxidizing responses. As exaggerated redox-responses were already evident in neonatal MeCP2-deficient neurons, they may contribute remarkably to the altered neuronal network performance and the disturbed neuronal signaling, which are among the hallmarks of RTT.

Efficient Collection and Representation of Preverbal Data in Typical and Atypical Development

Human preverbal development refers to the period of steadily increasing vocal capacities until the emergence of a child's first meaningful words. Over the last decades, research has intensively focused on preverbal behavior in typical development. Preverbal vocal patterns have been phonetically classified and acoustically characterized. More recently, specific preverbal phenomena were discussed to play a role as early indicators of atypical development. Recent advancements in audio signal processing and machine learning have allowed for novel approaches in preverbal behavior analysis including automatic vocalization-based differentiation of typically and atypically developing individuals. In this paper, we give a methodological overview of current strategies for collecting and acoustically representing preverbal data for intelligent audio analysis paradigms. Efficiency in the context of data collection and data representation is discussed. Following current research trends, we set a special focus on challenges that arise when dealing with preverbal data of individuals with late detected developmental disorders, such as autism spectrum disorder or Rett syndrome.

Efficient Collection and Representation of Preverbal Data in Typical and Atypical Development

Human preverbal development refers to the period of steadily increasing vocal capacities until the emergence of a child's first meaningful words. Over the last decades, research has intensively focused on preverbal behavior in typical development. Preverbal vocal patterns have been phonetically classified and acoustically characterized. More recently, specific preverbal phenomena were discussed to play a role as early indicators of atypical development. Recent advancements in audio signal processing and machine learning have allowed for novel approaches in preverbal behavior analysis including automatic vocalization-based differentiation of typically and atypically developing individuals. In this paper, we give a methodological overview of current strategies for collecting and acoustically representing preverbal data for intelligent audio analysis paradigms. Efficiency in the context of data collection and data representation is discussed. Following current research trends, we set a special focus on challenges that arise when dealing with preverbal data of individuals with late detected developmental disorders, such as autism spectrum disorder or Rett syndrome.

Non-medical interventions for individuals with Rett syndrome: A systematic review

BACKGROUND

Research into Rett syndrome has included various medical interventions. Non-medical interventions are relatively under-researched. Recent technological communication intervention advances have contributed to the evidence base in Rett syndrome.

METHOD

The Embase, PsycINFO and MEDLINE were systematically searched for peer-reviewed papers describing non-medical interventions for Rett syndrome. All identified papers were evaluated for methodological quality.

RESULTS

Thirteen studies of adequate methodological quality were reviewed (across N = 60 participants). Interventions were primarily communication interventions including music, assistive technology, augmentative and alternative communication strategies, attentional training and cognitive rehabilitation training. All studies reported positive outcomes across communication, quality of life, brain stem activity, physical fitness and a reduction in stereotyped behaviour. However, methodological challenges to generalizability, standardization, lack of follow-up and/or small-N samples were common.

CONCLUSIONS

The review highlights the paucity of high-quality research. Future research is needed to build on current research and improve validity and generalizability of interventions.

Experimental Examination and Social Validation of a Microswitch Intervention to Improve Choice-Making and Activity Engagement for Six Girls with Rett Syndrome

Background: The use of assistive technology, specifically microswitches, with children with RTT has been shown to effectively moderate the impact of their disability on their quality of life^- by facilitating access to meaningful leisure and other activities. Objectives: This study aimed to evaluate the effectiveness of a microswitch intervention on increased choice making, engagement in a targeted sorting activity, and indices of happiness, and decreased stereotypic behaviors for six girls with Rett syndrome. Targeted dependent variables were also assessed at six months post-intervention. Following the intervention study, 90 external raters completed a social validation procedure. Method: An ABABAB experimental sequence was implemented for each participant with a cross-over effect. A social validation assessment involving 90 external raters was carried out. Results: Data emphasized an improved performance for each participants involved (i.e., adaptive responses). Five participants showed a capacity of independent choice. One participant seemed to be closely linked to the position of the container. Social raters favorably endorsed the use of the program since they positively evaluated the use of the technology on all the dimensions investigated. Conclusion: A microswitch intervention may improve choice making and activity engagement for children with Rett syndrome. Further research is needed on the development of more sophisticated forms of individualized technological options to improve opportunities for enhanced engagement and choice-making for individuals with RTT.

MeCP2: A Critical Regulator of Chromatin in Neurodevelopment and Adult Brain Function

Methyl CpG binding protein 2 (MeCP2) was first identified as a nuclear protein with a transcriptional repressor role that recognizes DNA methylation marks. MeCP2 has a well-established function in neurodevelopment, as evidenced by the severe neurological impairments characteristic of the Rett syndrome (RTT) pathology and the MeCP2 duplication syndrome (MDS), caused by loss or gain of MeCP2 function, respectively. Research aimed at the underlying pathophysiological mechanisms of RTT and MDS has significantly advanced our understanding of MeCP2 functions in the nervous system. It has revealed, however, that MeCP2 has more varied and complex roles than previously thought. Here we review recent insights into the functions of MeCP2 in neurodevelopment and the less explored requirement for MeCP2 in adult brain function. We focus on the emerging view that MeCP2 is a global chromatin organizer. Finally, we discuss how the individual functions of MeCP2 in neurodevelopment and adulthood are linked to its role as a chromatin regulator.

Sensory Integration and Functional Reaching in Children With Rett Syndrome/Rett-Related Disorders

Background

The loss of functional hand skills is a primary characteristic of Rett syndrome. Stereotypies, dyspraxia, and other sensory processing issues severely limit the individual's ability to reach toward and sustain grasp on objects. This loss of functional reach and grasp severely limits their ability to participate in self-help, play, and school-related activities. We proposed that Ayres Sensory Integration (ASI) treatment would improve sensory processing and motor planning, which would lay the sensory-motor groundwork for improving grasp of objects, an important first step in developing functional hand use.

Objective

We examined effects of ASI treatment on rate of reaching and grasping for children with Rett syndrome/Rett-related disorders.

Methods

We used an interrupted time series design to measure changes in outcome variables occurring after intervention initiation and cessation. We analyzed daily video observations during baseline, intervention, and post-intervention periods, over a span of 7 months.

Results

During baseline, rate of grasping declined moderately. There was a 15% increase in grasping from the end of baseline to end of the post-intervention period. There was no significant change in rate of reaching.

Conclusions

This study provides preliminary data showing very small improvements in hand grasp of children with Rett syndrome following ASI treatment; larger studies in diverse settings are needed to establish the effectiveness of this approach. This study shows that an interrupted time series research design provides a valid template for evaluating interventions for children with rare disorders.

Identifying Atypical Development: A Role of Day-Care Workers?

Identifying the early signs of developmental disability is important for ensuring timely diagnosis and early intervention. Day-care workers may be in a prime position to notice potential developmental deviations, but it is unclear if they can accurately recognize subtle early signs of atypical development. Sixty day-care workers examined home-videos of very young children with fragile X syndrome and typically developing children. Results indicated that most day-care workers can distinguish typical and atypical development in general and might therefore have an important role in early identification. Special work experience and advanced pedagogical training appeared to boost day-care workers' sensitivity to detect atypical features in early development and to provide effective daily surveillance.

Rett syndrome: insights into genetic, molecular and circuit mechanisms

Rett syndrome (RTT) is a severe neurological disorder caused by mutations in the gene encoding methyl-CpG-binding protein 2 (MeCP2). Almost two decades of research into RTT have greatly advanced our understanding of the function and regulation of the multifunctional protein MeCP2. Here, we review recent advances in understanding how loss of MeCP2 impacts different stages of brain development, discuss recent findings demonstrating the molecular role of MeCP2 as a transcriptional repressor, assess primary and secondary effects of MeCP2 loss and examine how loss of MeCP2 can result in an imbalance of neuronal excitation and inhibition at the circuit level along with dysregulation of activity-dependent mechanisms. These factors present challenges to the search for mechanism-based therapeutics for RTT and suggest specific approaches that may be more effective than others.

Rett Syndrome and Other Neurodevelopmental Disorders Share Common Changes in Gut Microbial Community: A Descriptive Review

In this narrative review, we summarize recent pieces of evidence of the role of microbiota alterations in Rett syndrome (RTT). Neurological problems are prominent features of the syndrome, but the pathogenic mechanisms modulating its severity are still poorly understood. Gut microbiota was recently demonstrated to be altered both in animal models and humans with different neurodevelopmental disorders and/or epilepsy. By investigating gut microbiota in RTT cohorts, a less rich microbial community was identified which was associated with alterations of fecal microbial short-chain fatty acids. These changes were positively correlated with severe clinical outcomes. Indeed, microbial metabolites can play a crucial role both locally and systemically, having dynamic effects on host metabolism and gene expression in many organs. Similar alterations were found in patients with autism and down syndrome as well, suggesting a potential common pathway of gut microbiota involvement in neurodevelopmental disorders.

Early alterations in a mouse model of Rett syndrome: the GABA developmental shift is abolished at birth

Genetic mutations of the Methyl-CpG-binding protein-2 (MECP2) gene underlie Rett syndrome (RTT). Developmental processes are often considered to be irrelevant in RTT pathogenesis but neuronal activity at birth has not been recorded. We report that the GABA developmental shift at birth is abolished in CA3 pyramidal neurons of Mecp2^-/y mice and the glutamatergic/GABAergic postsynaptic currents (PSCs) ratio is increased. Two weeks later, GABA exerts strong excitatory actions, the glutamatergic/GABAergic PSCs ratio is enhanced, hyper-synchronized activity is present and metabotropic long-term depression (LTD) is impacted. One day before delivery, maternal administration of the NKCC1 chloride importer antagonist bumetanide restored these parameters but not respiratory or weight deficits, nor the onset of mortality. Results suggest that birth is a critical period in RTT with important alterations that can be attenuated by bumetanide raising the possibility of early treatment of the disorder.

Canonical Babbling: A Marker for Earlier Identification of Late Detected Developmental Disorders?

PURPOSE OF REVIEW

To summarize findings about the emergence and characteristics of canonical babbling in children with late detected developmental disorders (LDDDs), such as autism spectrum disorder, Rett syndrome, and fragile X syndrome. In particular, we ask whether infants' vocal development in the first year of life contains any markers that may contribute to earlier detection of these disorders.

RECENT FINDINGS

Only a handful studies have investigated canonical babbling in infants with LDDDs. With divergent research paradigms and definitions applied, findings on the onset and characteristics of canonical babbling are inconsistent and difficult to compare. Infants with LDDDs showed reduced likelihood to produce canonical babbling vocalizations. If achieved, this milestone was more likely to be reached beyond the critical time window of 5-10 months.

SUMMARY

Canonical babbling appears promising as a potential marker for early detection of infants at risk for developmental disorders. In-depth studies on babbling characteristics in LDDDs are warranted.

Rett syndrome before regression: A time window of overlooked opportunities for diagnosis and intervention

Rett syndrome (RTT) is a rare neurological disorder primarily affecting females, causing severe cognitive, social, motor and physiological impairments for which no cure currently exists. RTT clinical diagnosis is based on the peculiar progression of the disease, since patients show an apparently normal initial development with a subsequent sudden regression at around 2 years of age. Accumulating evidences are rising doubts regarding the absence of early impairments, hence questioning the concept of regression. We reviewed the published literature addressing the pre-symptomatic stage of the disease in both patients and animal models with a particular focus on behavioral, physiological and brain abnormalities. The emerging picture delineates subtle, but reliable impairments that precede the onset of overt symptoms whose bases are likely set up already during embryogenesis. Some of the outlined alterations appear transient, suggesting compensatory mechanisms to occur in the course of development. There is urgent need for more systematic developmental analyses able to detect early pathological markers to be used as diagnostic tools and precocious targets of time-specific interventions.

Early motor and pre-linguistic verbal development in Prader-Willi syndrome - A case report

BACKGROUND

Prader-Willi syndrome (PWS) is a rare genetic disorder. Infants with PWS show a neurodevelopmental dysfunction which entails a delayed motor and language development, but studies on their spontaneous movements (i.e. general movements) or pre-linguistic speech-language development before 6 months of age are missing so far.

AIM

To describe early motor and pre-linguistic verbal development in an infant with PWS.

METHODS AND PROCEDURES

Prospective case report; in addition to the assessment of general movements and the concurrent movement repertoire, we report on early verbal forms, applying the Stark Assessment of Early Vocal Development-Revised.

OUTCOMES AND RESULTS

General movements were abnormal on days 8 and 15. No fidgety movements were observed at 11 weeks; they only emerged at 17 weeks and lasted until at least 27 weeks post-term. The movement character was monotonous, and early motor milestones were only achieved with a delay. At 27 weeks the infant produced age-adequate types of vocalisations. However, none of the canonical-syllable vocalisations that typically emerge at that age were observed. Early vocalisations appeared monotonous and with a peculiarly harmonic structure.

CONCLUSIONS AND IMPLICATIONS

Early motor and pre-linguistic verbal behaviours were monotonous in an infant with PWS throughout his first 6 months of life. This suggests that early signs of neurodevelopmental dysfunction (i.e. abnormal general movements) might already be diagnosed in infants with PWS during their first weeks of life, potentially enabling us to diagnose and intervene at an early stage.

Regression in autism spectrum disorder: A critical overview of retrospective findings and recommendations for future research

Historically, two onset patterns in autism spectrum disorder (ASD) were described: early onset of symptoms and regression in which one-third appear to show a loss of previously established skills in the second year of life. Since this phenomenon could represent a distinct ASD subtype and provide more insight into the etiology, diagnosis, and prognosis, many studies have compared these two groups. The present review discusses definitions, etiology, and methods used in research with a retrospective design and provides an overview of the results on early development and outcomes. However, retrospective research has not provided clear answers on regression as a distinct subtype of ASD and the historic division between early onset and regression does not seem to fit the empirical findings. Based on inconsistent results, future research on onset patterns in ASD needs to be more systematic on the definitions and methods used. Several recommendations to enhance the reliability of future retrospective results are discussed. The combination of a categorical and dimensional approach provides a new interesting framework.

Disturbed redox homeostasis and oxidative stress: Potential players in the developmental regression in Rett syndrome

Rett syndrome (RTT) is a neurodevelopmental disorder affecting mostly girls. A seemingly normal initial development is followed by developmental stagnation and regression, leading to severe mental impairment with autistic features, motor dysfunction, irregular breathing and epilepsy. Currently, a cure does not exist. Due to the close association of RTT with mitochondrial alterations, cellular redox-impairment and oxidative stress, compounds stabilizing mitochondrial function, cellular redox-homeostasis, and oxidant detoxification are increasingly considered as treatment concepts. Indeed, antioxidants and free-radical scavengers ameliorate certain aspects of the complex and severe clinical presentation of RTT. To further evaluate these strategies, reliable biosensors are needed to quantify redox-conditions in brain and peripheral organs of mouse models or in patient-derived cells. Genetically-encoded redox-sensors meet these requirements. Expressed in transgenic mouse-models such as our unique Rett-redox indicator mice, they will report for any cell type desired the severity of oxidant stress throughout the various disease stages of RTT. Furthermore, these sensors will be crucial to evaluate in vitro and in vivo the outcome of mitochondria- and redox-balance targeted treatments.

Typical vs. atypical: Combining auditory Gestalt perception and acoustic analysis of early vocalisations in Rett syndrome

BACKGROUND

Early speech-language development of individuals with Rett syndrome (RTT) has been repeatedly characterised by a co-occurrence of apparently typical and atypical vocalisations.

AIMS

To describe specific features of this intermittent character of typical versus atypical early RTT-associated vocalisations by combining auditory Gestalt perception and acoustic vocalisation analysis.

METHODS AND PROCEDURES

We extracted N = 363 (pre-)linguistic vocalisations from home video recordings of an infant later diagnosed with RTT. In a listening experiment, all vocalisations were assessed for (a)typicality by five experts on early human development. Listeners' auditory concepts of (a)typicality were investigated in context of a comprehensive set of acoustic time-, spectral- and/or energy-related higher-order features extracted from the vocalisations.

OUTCOMES AND RESULTS

More than half of the vocalisations were rated as 'atypical' by at least one listener. Atypicality was mainly related to the auditory attribute 'timbre', and to prosodic, spectral, and voice quality features in the acoustic domain.

CONCLUSIONS AND IMPLICATIONS

Knowledge gained in our study shall contribute to the generation of an objective model of early vocalisation atypicality. Such a model might be used for increasing caregivers' and healthcare professionals' sensitivity to identify atypical vocalisation patterns, or even for a probabilistic approach to automatically detect RTT based on early vocalisations.

The course of awake breathing disturbances across the lifespan in Rett syndrome

Rett syndrome (RTT), an X-linked dominant neurodevelopmental disorder caused by mutations in MECP2, is associated with a peculiar breathing disturbance exclusively during wakefulness that is distressing, and can even prompt emergency resuscitation. Through the RTT Natural History Study, we characterized cross sectional and longitudinal characteristics of awake breathing abnormalities in RTT and identified associated clinical features. Participants were recruited from 2006 to 2015, and cumulative lifetime prevalence of breathing dysfunction was determined using the Kaplan-Meier estimator. Risk factors were assessed using logistic regression. Of 1205 participants, 1185 had sufficient data for analysis, including 922 females with classic RTT, 778 of whom were followed longitudinally for up to 9.0 years, for a total of 3944 person-years. Participants with classic or atypical severe RTT were more likely to have breathing dysfunction (nearly 100% over the lifespan) compared to those with atypical mild RTT (60-70%). Remission was common, lasting 1 year on average, with 15% ending the study in terminal remission. Factors associated with higher odds of severe breathing dysfunction included poor gross and fine motor function, frequency of stereotypical hand movements, seizure frequency, prolonged corrected QT interval on EKG, and two quality of life metrics: caregiver concern about physical health and contracting illness. Factors associated with lower prevalence of severe breathing dysfunction included higher body mass index and head circumference Z-scores, advanced age, and severe scoliosis or contractures. Awake breathing dysfunction is common in RTT, more so than seizures, and is associated with function, quality of life and risk for cardiac dysrhythmia.

Early Vocal Development in Autism Spectrum Disorder, Rett Syndrome, and Fragile X Syndrome: Insights from Studies using Retrospective Video Analysis

This article provides an overview of studies assessing the early vocalisations of children with autism spectrum disorder (ASD), Rett syndrome (RTT), and fragile X syndrome (FXS) using retrospective video analysis (RVA) during the first two years of life. Electronic databases were systematically searched and a total of 23 studies were selected. These studies were then categorised according to whether children were later diagnosed with ASD (13 studies), RTT (8 studies), or FXS (2 studies), and then described in terms of (a) participant characteristics, (b) control group characteristics, (c) video footage, (d) behaviours analysed, and (e) main findings. This overview supports the use of RVA in analysing the early development of vocalisations in children later diagnosed with ASD, RTT or FXS, and provides an in-depth analysis of vocalisation presentation, complex vocalisation production, and the rate and/or frequency of vocalisation production across the three disorders. Implications are discussed in terms of extending crude vocal analyses to more precise methods that might provide more powerful means by which to discriminate between disorders during early development. A greater understanding of the early manifestation of these disorders may then lead to improvements in earlier detection.

Placebo-controlled crossover assessment of mecasermin for the treatment of Rett syndrome

Objective

To measure the efficacy of mecasermin (recombinant human insulin-like growth factor 1, rhIGF-1), for treating symptoms of Rett syndrome (RTT) in a pediatric population using a double-blind crossover study design.

Methods

Thirty girls with classic RTT in postregression stage were randomly assigned to placebo or rhIGF-1 in treatment period 1 and crossed over to the opposite assignment for period 2 (both 20 weeks), separated by a 28-week washout period. The primary endpoints were as follows: Anxiety Depression and Mood Scale (ADAMS) Social Avoidance subscale, Rett Syndrome Behaviour Questionnaire (RSBQ) Fear/Anxiety subscale, Parent Target Symptom Visual Analog Scale (PTSVAS) top three concerns, Clinical Global Impression (CGI), Parent Global Impression (PGI), and the Kerr severity scale. Cardiorespiratory- and electroencephalography (EEG)-based biomarkers were also analyzed.

Results

There were no significant differences between randomization groups. The majority of AEs were mild to moderate, although 12 episodes of serious AEs occurred. The Kerr severity scale, ADAMS Depressed Mood subscale, Visual Analog Scale Hyperventilation, and delta average power change scores significantly increased, implying worsening of symptoms. Electroencephalography (EEG) parameters also deteriorated. A secondary analysis of subjects who were not involved in a placebo recall confirmed most of these findings. However, it also revealed improvements on a measure of stereotypic behavior and another of social communication.

Interpretation

As in the phase 1 trial, rhIGF-1 was safe; however, the drug did not reveal significant improvement, and some parameters worsened.

Early development in Rett syndrome - the benefits and difficulties of a birth cohort approach

PURPOSES

Typically, early (pre-diagnostic) development in individuals later diagnosed with Rett syndrome (RTT) has been investigated retrospectively using parent reports, medical records and analysis of home videos. In recent years, prospective research designs have been increasingly applied to the investigation of early development in individuals with late phenotypical onset disorders, for example, autism spectrum disorder.

METHODS

In this study, data collected by the Danish National Birth Cohort lent itself to prospective exploration of the early development of RTT, in particular early motor-, speech-language, and socio-communicative behaviors, mood, and sleep.

RESULTS AND CONCLUSIONS

Despite limitations, this quasi prospective methodology proved promising. In order to add substantially to the body of knowledge, however, specific questions relating to peculiarites in early development could usefully be added to future cohort studies. As this involves considerable work, it may be more realistic to consider a set of indicators which point to a number of developmental disorders rather than to one.

Defining Hand Stereotypies in Rett Syndrome: A Movement Disorders Perspective

INTRODUCTION

Hand stereotypies (HS) are a primary diagnostic criterion for Rett syndrome (RTT) but are difficult to characterize and quantify systematically.

METHODS

We collected video on 27 girls (2-12 years of age) with classic RTT who participated in a mecasermin trial. The present study focused exclusively on video analyses, by reviewing two five-minute windows per subject to identify the two most common HS. Three raters with expertise in movement disorders independently rated the five-minute windows using standardized terminology to determine the level of agreement. We iteratively refined the protocol in three stages to improve descriptive accuracy, categorizing HS as "central" or "peripheral," "simple" or "complex," scoring each hand separately. Inter-rater agreement was analyzed using Kappa statistics.

RESULTS

In the initial protocol evaluating HS by video, inter-rater agreement was 20.7%. In the final protocol, inter-rater agreement for the two most frequent HS was higher than the initial protocol at 50%.

CONCLUSION

Phenotypic variability makes standardized evaluation of HS in RTT a challenge; we achieved only 50% level of agreement and only for the most frequent HS. Therefore, objective measures are needed to evaluate HS.

A Novel Way to Measure and Predict Development: A Heuristic Approach to Facilitate the Early Detection of Neurodevelopmental Disorders

PURPOSE OF REVIEW

Substantial research exists focusing on the various aspects and domains of early human development. However, there is a clear blind spot in early postnatal development when dealing with neurodevelopmental disorders, especially those that manifest themselves clinically only in late infancy or even in childhood.

RECENT FINDINGS

This early developmental period may represent an important timeframe to study these disorders but has historically received far less research attention. We believe that only a comprehensive interdisciplinary approach will enable us to detect and delineate specific parameters for specific neurodevelopmental disorders at a very early age to improve early detection/diagnosis, enable prospective studies and eventually facilitate randomised trials of early intervention. In this article, we propose a dynamic framework for characterising neurofunctional biomarkers associated with specific disorders in the development of infants and children. We have named this automated detection 'Fingerprint Model', suggesting one possible approach to accurately and early identify neurodevelopmental disorders.

A Novel Way to Measure and Predict Development: A Heuristic Approach to Facilitate the Early Detection of Neurodevelopmental Disorders

PURPOSE OF REVIEW

Substantial research exists focusing on the various aspects and domains of early human development. However, there is a clear blind spot in early postnatal development when dealing with neurodevelopmental disorders, especially those that manifest themselves clinically only in late infancy or even in childhood.

RECENT FINDINGS

This early developmental period may represent an important timeframe to study these disorders but has historically received far less research attention. We believe that only a comprehensive interdisciplinary approach will enable us to detect and delineate specific parameters for specific neurodevelopmental disorders at a very early age to improve early detection/diagnosis, enable prospective studies and eventually facilitate randomised trials of early intervention. In this article, we propose a dynamic framework for characterising neurofunctional biomarkers associated with specific disorders in the development of infants and children. We have named this automated detection 'Fingerprint Model', suggesting one possible approach to accurately and early identify neurodevelopmental disorders.

Rett Syndrome: A Focus on Gut Microbiota

Rett syndrome (RTT) is an X-linked neurodevelopmental disorder affecting 1 in 10,000 live female births. Changes in microbiota composition, as observed in other neurological disorders such as autism spectrum disorders, may account for several symptoms typically associated with RTT. We studied the relationship between disease phenotypes and microbiome by analyzing diet, gut microbiota, and short-chain fatty acid (SCFA) production. We enrolled eight RTT patients and 10 age- and sex-matched healthy women, all without dietary restrictions. The microbiota was characterized by 16S rRNA gene sequencing, and SCFAs concentration was determined by gas chromatographic analysis. The RTT microbiota showed a lower α diversity, an enrichment in Bacteroidaceae, Clostridium spp., and Sutterella spp., and a slight depletion in Ruminococcaceae. Fecal SCFA concentrations were similar, but RTT samples showed slightly higher concentrations of butyrate and propionate, and significant higher levels in branched-chain fatty acids. Daily caloric intake was similar in the two groups, but macronutrient analysis showed a higher protein content in RTT diets. Microbial function prediction suggested in RTT subjects an increased number of microbial genes encoding for propionate and butyrate, and amino acid metabolism. A full understanding of these critical features could offer new, specific strategies for managing RTT-associated symptoms, such as dietary intervention or pre/probiotic supplementation.

The roles of motor activity and environmental enrichment in intellectual disability

In people with intellectual disabilities, an enriched environment can stimulate the acquisition of motor skills and could partially repair neuronal impairment thanks to exploration and motor activity. A deficit in environmental and motor stimulation leads to low scores in intelligence tests and can cause serious motor skill problems. Although studies in humans do not give much evidence for explaining basic mechanisms of intellectual disability and for highlighting improvements due to enriched environmental stimulation, animal models have been valuable in the investigation of these conditions. Here, we discuss the role of environmental enrichment in four intellectual disabilities: Foetal Alcohol Spectrum Disorder (FASD), Down, Rett, and Fragile X syndromes.

Rett syndrome: a wide clinical and autonomic picture

Background

Rett Syndrome is a neurodevelopmental disorder almost exclusively affecting females, characterized by a broad clinical spectrum of signs and symptoms and a peculiar course. The disease affects different body systems: nervous, muscolo-skeletal, gastro-enteric. Moreover, part of the symptoms are related to the involvement of the autonomic nervous system.

In the Tuscany Rett Center at Versilia Hospital, we collected data from 151 subjects with a clinical diagnosis of classical or variant RTT syndrome. For each subject, we assessed the severity of the condition with clinical-rating scales (ISS, PBZ), we quantified the performance of the autonomic nervous system, and we performed genetic analysis. We used multivariate statistical analysis of the data to evaluate the relation between the different clinical RTT forms, the cardiorespiratory phenotype, the different genetic mutations and the severity of the clinical picture. Individuals were classified according to existing forms: Classical RTT and three atypical RTT: Z-RTT, Hanefeld, Congenital. A correlation between C-Terminal deletions and lower severity of the clinical manifestations was evident, in the previous literature, but, considering the analysis of autonomic behaviour, the original classification can be enriched with a more accurate subdivision of Rett subgroups, which may be useful for early diagnosis.

Results

Present data emphasize some differences, not entirely described in the literature, among RTT variants. In our cohort the Z-RTT variant cases show clinical features (communication, growth, epilepsy and development), well documented by specific ISS items, less severe, if compared to classical RTT and show autonomic disorders, previously not reported in the literature. In this form epilepsy is rarely present. In contrast, Hanefeld variant shows the constant presence of epilepsy which has an earlier onset In Hanefeld variant the frequency of apneas was rare and, among the cardiorespiratory phenotypes, the feeble type is lacking.

Conclusion

A quantitative analysis of the different autonomic components reveals differences across typical and atypical forms of RTT that leads to a more accurate classification of the groups. In our cohort of RTT individuals, the inclusion of autonomic parameter in the classification leads to an improved diagnosis at earlier stages of development.

Behavioural biomarkers of typical Rett syndrome: moving towards early identification

The dynamic course of Rett syndrome (RTT) is still said to begin with a period of apparently normal development although there is mounting evidence that individuals with RTT show behavioural peculiarities and abnormalities during their infancy. Their spontaneous general movements are abnormal from birth onwards. Normal cooing vocalisation and canonical babbling (if at all required) are interspersed with abnormalities such as proto-vowel and proto-consonant alternations produced on ingressive airstream, breathy voice characteristics, and pressed or high-pitched vocalisations. The gestural repertoire is limited. Certain developmental motor and speech-language milestones are not at all acquired or show a significant delay. Besides abnormal blinking, repetitive and/or long lasting tongue protrusion, and bizarre smiling, there are already the first body and/or hand stereotypies during the first year of life. We are currently on a promising way to define a specific set of behavioural biomarkers pinpointing RTT.

Progress in Rett Syndrome: from discovery to clinical trials

Fifty years ago, Andreas Rett described a disorder in 22 females featuring prominent regression of fine motor and communication skills, cognitive impairment, stereotypic movements, periodic breathing, and gait abnormalities. This disorder became known as Rett syndrome (RTT) following the report of Hagberg et al. in 1983. Although RTT was scarcely recognized at that time in the United States, here the efforts of Rett and Hagberg led to rapid progress in recognition and diagnosis, a clearer understanding of its clinical and pathological underpinnings, and, ultimately, identification of mutations in the methyl-CpG-binding protein 2 (MECP2) gene as the primary cause of this unique and challenging neurodevelopmental disorder. Thereafter, a natural history study and critical translational research in animal models paved the way for potential disease-modifying agents to be assessed in human clinical trials. To be successful, the energies of the international community at all levels, including researchers in clinical and basic science, funding agencies, pharmaceutical companies, patient advocates, and, above all, parents and their children are essential. Otherwise, hopes for effective treatment, if not, a cure, will remain unfulfilled.

Quantitative and qualitative insights into the experiences of children with Rett syndrome and their families

Rett syndrome is a rare neurodevelopmental disorder caused by a mutation in the MECP2 gene. It is associated with severe functional impairments and medical comorbidities such as scoliosis and poor growth. The population-based and longitudinal Australian Rett Syndrome Database was established in 1993 and has supported investigations of the natural history of Rett syndrome and effectiveness of treatments, as well as a suite of qualitative studies to identify deeper meanings. This paper describes the early presentation of Rett syndrome, including regression and challenges for families seeking a diagnosis. We discuss the importance of implementing strategies to enhance daily communication and movement, describe difficulties interpreting the presence of pain and discomfort, and argue for a stronger evidence base in relation to management. Finally, we outline a framework for understanding quality of life in Rett syndrome and suggest areas of life to which we can direct efforts in order to improve quality of life. Each of these descriptions is illustrated with vignettes of child and family experiences. Clinicians and researchers must continue to build this framework of knowledge and understanding with efforts committed to providing more effective treatments and supporting the best quality of life for those affected.

Spinal Fusion for Scoliosis in Rett Syndrome With an Emphasis on Respiratory Failure and Opioid Usage

Our objective was to characterize our experience with 8 patients with Rett syndrome undergoing scoliosis surgery in regard to rates of respiratory failure and rates of ventilator-acquired pneumonia in comparison to patients with neurologic scoliosis and adolescent idiopathic scoliosis. This study was a retrospective chart review of patients undergoing scoliosis surgery at a tertiary children's hospital. Patients were divided into 3 groups: (1) adolescent idiopathic scoliosis, (2) neurologic scoliosis, and (3) Rett syndrome. There were 133 patients with adolescent idiopathic scoliosis, 48 patients with neurologic scoliosis, and 8 patients with Rett syndrome. We found that patients with Rett syndrome undergoing scoliosis surgery have higher rates of respiratory failure and longer ventilation times in the postoperative period when compared with both adolescent idiopathic scoliosis and neurologic scoliosis patients. There is insufficient evidence to suggest a difference in the incidence of ventilator-acquired pneumonia between the Rett syndrome and the neurologic scoliosis group. We believe our findings are the first in the literature to show a statistically significant difference between these 3 groups in regard to incidence of respiratory failure.