Three different profiles: Early socio-communicative capacities in typical Rett syndrome,the preserved speech variant and normal development

Background and aims: This is the first study aiming to compare pre-diagnostic socio-communicative development of a female with typical Rett syndrome (RTT), a female with the preserved speech variant of RTT (PSV) and a control toddler.

Methods: We analysed 1275?min of family videos at the participants’ age between 9 and 24 months and used the Inventory of Potential Communicative Acts (IPCA) to delineate their repertoires of communicative forms and functions.

Results: The results revealed different profiles for the three different conditions. The repertoire of communicative gestures and (pre)linguistic vocalizations was most comprehensive in the control toddler, followed by the female with PSV and the female with RTT.

Conclusion: These findings contribute to the growing knowledge about early developmental abnormalities in RTT. In order to define distinctive profiles for typical and atypical RTT and evaluate their specificity, a larger body of evidence is needed.     

Cytogenetic and molecular-cytogenetic studies of Rett syndrome (RTT): a retrospective analysis of a Russian cohort of RTT patients (the investigation of 57 girls and three boys)

Rett syndrome (RTT) is a severe neurodevelopmental disorder with an incidence of 2.5% in mentally retarded girls in Russia. We have performed cytogenetic studies of 60 patients (57 girls and three boys) with a clinical picture of RTT, selected according to the criteria for diagnosis of RTT defined by B. Hagberg et al. in 1996. Collection of DNA samples and fixed cell suspensions of RTT patients (37 girls and two boys) and their parents (27 patients) was established for molecular studies, for example analysis of MECP2 mutations in a Russian cohort of RTT patients. Among 60 patients 57 girls with a clinical picture of RTT had normal female karyotype (46,XX), one boy had normal male karyotype in peripheral lymphocytes (46,XY) and two boys had a mosaic form of Kleinfelter's syndrome (47,XXY/46,XY) in peripheral lymphocytes or muscle cells (with MeCP2 mutation R270X). Twenty-four mothers and parents of RTT girls had normal karyotype, two mothers had mosaic forms of Turner syndrome (45,X/46,XX) and one had mosaic karyotype (47,XX,+mar/48,XXX,+mar). We analyzed chromosome X in lymphocytes of 57 affected girls with a clinical picture of RTT using the 5-bromo-2′-deoxyuridine+Giemsa staining technique. A specific type of inactive chromosome X (so-called type ‘C’) with unusual staining of chromatin in the long arm of chromosome X was found in 55 (from 57) girls with RTT. This technique was positively used for presymptomatic diagnosis of RTT in five girls in earlier stages of the disease. We believe that the phenomenon of altered chromatin conformation in inactive chromosome X could be used as a laboratory test for preclinical diagnosis of the RTT.     

Early socio-communicative forms and functions in typical Rett syndrome

Rett syndrome (RTT) is a severe neurological disorder characterized by a developmental regression in motor and speech-language domains. There is, however, limited research on socio-communicative development of affected children before the onset of regression. We analyzed audio–video recordings made by parents of six 9- to 12-month old girls later diagnosed with typical RTT, applying the Inventory of Potential Communicative Acts (IPCA) to identify early communicative forms and functions. Each girl used at least one communicative form (e.g., body movement, eye gaze, or vocalizations) to gain attention and answer, but none were observed to make choices or request information. Varying numbers of children were observed to perform other communicative functions according to the IPCA including social convention, rejecting or requesting an object. Non-verbal forms (e.g., reaching, moving closer, eye contact, smiling) were more common than non-linguistic verbal forms (e.g., unspecified vocalizations, pleasure vocalizations, crying). (Pre-)linguistic verbal forms (e.g., canonical or variegated babbling, proto-words) were not used for communicative purposes. These data suggest that atypical developmental patterns in the socio-communicative domain are evident prior to regression in young individuals later diagnosed with RTT.     

Early speech-language development in females with Rett syndrome: focusing on the preserved speech variant

Aim Our aim was to contribute new findings related to the pre‐regressional verbal development of females with a variant of Rett syndrome (RTT) as the loss of spoken language is one of the key clinical features of RTT, and it would be of particular interest to study the early speech–language development of females who are considered to have preserved some speech–language abilities. Method We analysed 461 minutes of audio–video recordings containing play situations and the daily routines of six females (aged 7 to 24 months; mean birthweight 3057g, SD 195g) with the preserved speech variant (PSV) of RTT. All videos were recorded by parents and analysed retrospectively after the diagnosis PSV was made. Results From the age of 7 months onwards, we observed two types of vocalizations, appearing intermittently: (1) apparently normal sequences; and (2) atypical (i.e. inhalatory, pressed, or high‐pitched crying‐like) vocalizations. Some participants failed to reach the milestone of canonical babbling. We observed a limited phonological and lexical complexity and a restricted compositional variability. Volubility was reduced during the whole period under observation. Hand stereotypies with simultaneous atypical vocalizations appeared only during the second year of life. Interpretation The intermittent character of normal versus abnormal verbal behaviours might contribute to an early identification of children with a possible genetic mutation, and provides evidence that speech–language functions are abnormal from the very beginning.     

Expression of global oxidative stress and matrix metalloproteinases is associated with rett syndrome

Rett syndrome (RTT) is characterized by microcephaly, cognitive impairment, abnormal muscle tone, epilepsy, and ataxia, yet misdiagnoses are not uncommon. Oxidative stress (OS) and matrix metalloproteinases (MMPs) has been implicated in a variety of neurological diseases and inflammatory conditions. The aims of the study were to investigate the serum values of global oxidative stress (OS) and levels of MMP-2 (gelatinase), MMP-9 and 13 (collagenase) in RTT girls, since we hypothesized that OS and MMPs play a role in the on-going pathological processes of RS leading to the progression and deterioration of their neurological functions. Total level of MMP-2, 9 and 13 were measured in serum of six RTT girls (average age of 14.2 ± 1.6) by ELISA, and global OS was measured by CR 3000 instrument, FORM system. The RTT girls had significant (p = 0.001) increased serum levels of MMP-2 (mean values) and MMP-9 (mean values), yet MMP-13 mean values were comparable to age-and-gender matched non RTT girls. OS values were significantly higher in RTT girls comparing control groups. The increased OS values and MMP-2 and 9 levels in RTT girls suggest their involvement in the chronic pathogenesis resulting in continuing neurological damage. Our findings can provide another aspect indicating certain MMPs and OS as possible biochemical markers and their potential application in future therapeutic strategies.     

Brain-directed autoantibodies levels in the serum of Rett syndrome patients

Increased titer of brain-directed autoantibodies (AAB) may represent a risk for brain development in children with Rett syndrome (RTT). The aims of this work were to study the levels of brain-directed AAB, mainly nerve growth factor (NGF) and S-100 protein AAB, to analyze morphological features of brain labeling by AAB produced in RTT patients, and to correlate with clinical manifestation. The increased titer of anti-NGF AAB, but not of anti-S100 AAB has been determined in the blood of RTT patients. The blood from five RTT girls was investigated repeatedly (two to four times) within 0.5–3 years. In these RTT patients the level of anti-NGF AAB was stable, not depending on the stage of illness, so individual stability of anti-NGF AAB levels have been detected. However, the negative correlation between the level of these AAB and severity of disease has been found: girls with the milder course of illness (with relative preservation of speech and locomotor functions, later disease onset, and later development of regressive symptoms) were characterized by the higher levels of AAB. The study also revealed immunohistochemical labeling of neuronal population with serum from RTT patients. Serum AAB from RTT cases labeled the cytoplasm and apical dendrites of pyramidal neurons in the neocortex and hippocampus, neurons in basal ganglia and brain stem, but not in the cerebellum of rats. Our results show the presence of brain-directed AAB in blood serum of RTT patients, which suggests an autoimmune component in pathogenesis of RTT.     

Choline Ameliorates Disease Phenotypes in Human iPSC Models of Rett Syndrome

Rett syndrome (RTT) is a postnatal neurodevelopmental disorder that primarily affects girls. Mutations in the methyl-CpG-binding protein 2 (MECP2) gene account for approximately 95 % of all RTT cases. To model RTT in vitro, we generated induced pluripotent stem cells (iPSCs) from fibroblasts of two RTT patients with different mutations (MECP2 ^R306C and MECP2 ^1155Δ32) in their MECP2 gene. We found that these iPSCs were capable of differentiating into functional neurons. Compared to control neurons, the RTT iPSC-derived cells had reduced soma size and a decreased amount of synaptic input, evident both as fewer Synapsin 1-positive puncta and a lower frequency of spontaneous excitatory postsynaptic currents. Supplementation of the culture media with choline rescued all of these defects. Choline supplementation may act through changes in the expression of choline acetyltransferase, an important enzyme in cholinergic signaling, and also through alterations in the lipid metabolite profiles of the RTT neurons. Our study elucidates the possible mechanistic pathways for the effect of choline on human RTT cell models, thereby illustrating the potential for using choline as a nutraceutical to treat RTT.     

Peculiarities in the gestural repertoire: An early marker for Rett syndrome?

We studied the gestures used by children with classic Rett syndrome (RTT) to provide evidence as to how this essential aspect of communicative functions develops. Seven participants with RTT were longitudinally observed between 9 and 18 months of life. The gestures used by these participants were transcribed and coded from a retrospective analysis of a video footage. Gestures were classified as deictic gestures, play schemes, and representational gestures. Results of the analysis showed that the majority of gestures observed were of deictic character. There were no gestures that could be classified as play schemes and only two (e.g., head nodding and waving bye bye) that were coded as representational or symbolic gestures. The overall repertoire of gestures, even though not necessarily delayed in it's onset, was characterized by little variability and a restricted pragmatic functionality. We conclude that the gestural abilities in girls with RTT appear to remain limited and do not constitute a compensatory mechanism for the verbal language modality.     

Change over a 16-month period in the psychological well-being of mothers of girls and women with Rett syndrome

Purpose: There is an emerging research literature on the experiences of family members of girls and women with Rett syndrome (RTT), but a lack of longitudinal data. Methods: Fifty mothers whose daughters had RTT were surveyed 16–17 months after an earlier cross-sectional study. Measures completed at both time points focused on maternal positive and negative psychological well-being and their daughters’ behavioral and emotional problems and RTT behavioral phenotype severity. Results: Maternal stress, anxiety, and depression demonstrated at least moderate levels of stability. Maternal positive perceptions were also moderately stable over 16–17 months. Longitudinal analyses suggested that their daughters’ behavioral and emotional problems rather than RTT behavioral phenotype severity predicted later maternal well-being. Conclusion: Mothers with RTT daughters experience chronic stress (persisting over time) but also ongoing positive perceptions. Practitioners should recognize positive perceptions and also consider targeted behavioral parent training to reduce behavior problems in individuals with RTT.     

Profiling early socio-communicative development in five young girls with the preserved speech variant of Rett syndrome

Rett syndrome (RTT) is a developmental disorder characterized by regression of purposeful hand skills and spoken language, although some affected children retain some ability to speech. We assessed the communicative abilities of five young girls, who were later diagnosed with the preserved speech variant of RTT, during the pre-regression period (aged 12-24 months). Videotapes, obtained by parents during routine family situations and celebrations, were analyzed to identify communicative forms and functions used by these toddlers. Non-verbal communicative forms dominated over verbal-communicative forms for six of the eight identified communication functions. Although the girls used various non-verbal forms to make requests, for example, none of the individuals were observed to make choices or request information. Early peculiarities in the speech-language domain during the first year of life became more prominent and evident during the second year of life as general differences between typical development and atypical development become more obvious in RTT. These findings highlight the importance of assessing socio-communicative forms and functions at early age in children with RTT. The results suggest that speech-language functions did not appear to play a major role in the children's communicative attempts. We conclude that, even among children with the preserved speech variant, socio-communicative deficits are present before regression and persist after this period.     

Molecular-cytogenetic investigation of skewed chromosome X inactivation in Rett syndrome

We have developed an approach to differentiate homologous X chromosomes in metaphase chromosomes and interphase nuclei by a fluorescence in situ hybridization (FISH) technique with chromosome X-specific alpha-satellite DNA probe. FISH analysis of metaphase chromosomes in a cohort of 33 girls with Rett syndrome (RTT) allowed us to detect eight girls with structurally different X chromosomes, one X chromosome with a large and another one with a small centromeric heterochromatin (so-called chromosomal heteromorphism). Step-wise application of differential replication staining and the FISH technique to identify the inactivation status of paternal and maternal chromosome X in RTT girls was applied. Skewed X inactivation in seven RTT girls with preferential inactivation of one X chromosome over the other X chromosome was detected in 62–93% of cells. Therefore, non-random or skewed X inactivation with variable penetrance in blood cells could take place in RTT.     

The spectrum of phenotypes in females with Rett Syndrome

Since the discovery of mutations in the methyl-CpG binding protein-2 (MECP2) gene in Rett Syndrome (RTT) a large number of females have been diagnosed worldwide. In this article we present the clinical and developmental data of 120 RTT females with mutations in the MECP2 gene and individually describe typical and atypical cases. We found a broad spectrum of phenotypes in females. At the severest end we have females with primary developmental delay who never learned to turn, sit or walk and who developed severe epilepsy. At the mildest end of the spectrum, there are females with only minor neurological symptoms who have good gross motor function, speak and have relatively well-preserved hand function. A number of girls either do not fulfil all the necessary diagnostic criteria or present with symptoms that have not been described in RTT before. Comparing our data with the normal population we found that girls with RTT have a smaller occipito-frontal circumference, shorter length and lower weight at birth. As a result of molecular genetic analysis a broad spectrum of phenotypes in RTT females has evolved. We found evidence that the defect in MeCP2 influences the somatic growth before birth.     

Methyl-CpG binding protein 2 gene (MECP2) variations in Japanese patients with Rett syndrome: pathological mutations and polymorphisms

A total of 45 different mutations of methyl-CpG-binding protein 2 gene (MECP2) were identified in 145 of 219 Japanese patients with typical or atypical Rett syndrome (RTT) (66.2%). A missense mutation, T158M was the most common mutation of MECP2, identified in 22 (19.1%) patients, followed by four nonsense mutations, R168X (14.8%), R270X (13.0%), R255X (9.6%), and R294X (6.1%) in 115 patients with classical RTT. Two missense mutations, R133C (33.3%) and R306C (23.3%), and a nonsense mutation, R294X (13.3%), were common in 30 patients with atypical RTT, including the preserved speech variant (PSV). Frameshift mutations due to nucleotide deletion or insertion were identified in 22 patients with MECP2 mutations, and one of them had a 3.6 kb deletion encompassing exons 3 and 4. Three patients with classical RTT had a splicing anomaly. The wide spectrum of phenotypic variability in patients with RTT has been considered to be correlated with the mutation type and location in MECP2, and X-inactivation. However, most patients showed a random X-inactivation pattern evaluated by an androgen receptor gene polymorphism in this study, suggesting that a skewed X-inactivation might not be a main modification factor on clinical phenotypes of RTT. In addition, three new missense mutations, P176R, A378V and T479M, were identified in patients with RTT, but also in healthy Japanese, indicating that these mutations are non-pathogenic in Japanese. Information about rare polymorphic variations is very important for the molecular diagnosis of RTT, although rare polymorphic variants might differ among ethnic groups.     

Clinical stringency greatly improves mutation detection in Rett syndrome

BACKGROUND: Rett syndrome (RTT) is a severe neurodevelopmental disorder of girls, caused by mutations in the X-linked MECP2 gene. Worldwide recognition of the RTT clinical phenotype in the early 1980's allowed many cases to be diagnosed, and established RTT as one of the most common mental retardation syndromes in females. The years since then led to a refinement of the phenotype and the recent elaboration of Revised Diagnostic Criteria (RDC). Here, we study the impact of the presence versus the absence of the use of diagnostic criteria from the RDC to make a diagnosis of RTT on MECP2 mutation detection in Canadian patients diagnosed and suspected of having RTT. METHODS: Using dHPLC followed by sequencing in all exons of the MECP2 gene, we compared mutation detection in a historic cohort of 35 patients diagnosed with RTT without the use of specific diagnostic criteria to a separate more recent group of 101 patients included on the basis of strict fulfillment of the RDC. RESULTS: The MECP2 mutation detection rate was much higher in subjects diagnosed using a strict adherence to the RDC (20% vs. 72%). CONCLUSIONS: These results suggest that clinical diagnostic procedures significantly influence the rate of mutation detection in RTT, and more generally emphasize the importance of diagnostic tools in the assessment of neurobehavioral syndromes.     

Highlighting the first 5 months of life: General movements in infants later diagnosed with autism spectrum disorder or Rett syndrome

We review literature identifying an association between motor abnormality in the first 5 months of infancy and later diagnosis of autism spectrum disorder (ASD) or Rett syndrome (RTT). The assessment of the quality of early spontaneous movements (also known as the assessment of general movements; GMs) is a diagnostic tool that has repeatedly proven to be valuable in detecting early markers for neurodevelopmental disorders. Even though the rate of occurrence of abnormal GMs is exceedingly high in infants later diagnosed with ASD, we endorse further studies using this method either based on family videos or its prospective implementation in high-risk sibling studies to evaluate the power of GM assessment as one potential marker for early maldevelopment in this cohort.     

Altered microtubule dynamics in Mecp2-deficient astrocytes

Rett syndrome (RTT) is a severe neurodevelopmental disorder caused by mutations in the gene MECP2 encoding the methyl-CpG binding protein 2. This genetic disease affects predominantly girls and is characterized by a period of normal development that lasts for 8-18 months, followed by neurologic regression affecting both motor and mental abilities. Previous studies performed on brains from RTT subjects and Mecp2-deficient mice showed striking changes in neuronal maturation and dendritic arborization. Recently, we showed that expression of stathmin-like 2 (STMN2) was significantly reduced in fibroblasts from RTT patients, and similar results were obtained in the cerebellum of Mecp2-deficient mice. Because assembly and dynamics of microtubules are known to be modulated by STMN2, we studied microtubule dynamics in brain cells from Mecp2-deficient mice. We observed that Mecp2 deficiency affects microtubule dynamics in astrocytes from Mecp2-deficient mice. Our data reinforce the fact that the loss of Mecp2 in astrocytes may influence the onset and progression of RTT. These results imply that Mecp2 has a stabilizing role in microtubule dynamics and that Mecp2 deficiency, which is associated with STMN2 down-regulation, could lead to impaired microtubule stability, hence explaining the dendritic abnormalities observed in RTT brains.     

Novel mutations in the C-terminal region of the MECP2 gene in Tunisian Rett syndrome patients

Rett syndrome (RTT), an X-linked dominant neurodevelopmental disorder in females, is caused mainly by de novo mutations in the methyl-CpG-binding protein 2 gene (MECP2). Rett patients present an apparently normal psychomotor development during the first 6 to 18 months of life. Thereafter, they show a short period of developmental stagnation followed by a rapid regression in language and motor development. In the present study, we performed a mutational analysis of the MECP2 gene in 2 typical Rett syndrome patients and in 1 atypical Rett syndrome girl. The results showed the presence of 3 de novo point mutations in the C-terminal region: 2 novel mutations: c.1065C>A (p.S355R) and c.1030C>G (p.R344G) in the 2 typical Rett syndrome girls, but also the c.996C>T (p.S332S) mutation first described in the atypical Rett syndrome patient.     

How Young Children Treat Objects and People: An Empirical Study of the First Year of Life in Autism

Objective. To figure out features of autism before the age of one and to explore the pathways of early social and nonsocial attention in autism through home movies.Method. Home movies of 15 children later diagnosed with autism, are compared with home movies of 13 typical children. The films of the two groups have been mixed and rated by blind observers through a Grid composed of social and nonsocial item and applied to two age ranges: 0–6 months (T1) and 7–12 months (T2). Two MANOVAs, an ANOVA and discriminant analyses were applied.Results. Significant differences between the two groups were found only for the item in the Social area at T1 but not at T2, when groups did not differ in either social or nonsocial areas. At T2 children with autism had significantly higher scores in the nonsocial area while normal children did not show significant differences between areas. Discriminant analyses revealed that social attention can distinguish the two groups at T1 but not at T2.Conclusions. The fundamental impairment of joint attention in autism could be considered a consequence of the early atypical developmental gap and of a later disconnection between attention to people and objects. Abnormal developmental trajectories for social and nonsocial attention could help us in the future to understand relationships between adaptive capacities and symptoms, and set the stage for appropriate early screening instruments.This study was supported by grant RC 6/02 from National Institute of Health.     

Clinical,neurophysiological and immunological correlations in classical Rett syndrome

Rett syndrome (RTT) is neurodevelopmental disorder with the onset at critical period of postnatal ontogenesis and age dependent occurrence of clinical manifestations. The aim of the present study was to investigate possible correlations of the age of disease onset with clinical manifestations at the stage 3 of illness and neurobiological parameters. The study was carried out in 38 girls with classical RTT, aged from 3 to 7 years, and twenty and eighteen patients with the disease onset before and after the age of one year were divided into the groups 1 and 2 (Gr1 and Gr2), respectively. Quantitative EEG (QEEG) and measurement of the serum levels of autoantibodies (AAB) to nerve growth factor (NGF) were performed. Clinically, speech and motor functions were significantly more severely affected in the Gr1 than in the Gr2. In QEEG, spectral density of theta activity was significantly higher in Gr1 than in the Gr2. The titer of AAB to NGF was significantly increased in comparison with healthy controls, and the titer in Gr2 was higher than in Gr1.The data obtained suggests that patients with the classical RTT can be divided into subgroups according to the age of disease onset and genetic factors such as mosaicism of MeCP2 mutation may be associated with the heterogeneity of phenotype in RTT patients.