Rett syndrome: geographic variation in prevalence in Norway

Individualized Remotely Supervised Motor Activity Programs Promote Rehabilitation Goal Achievement, Motor Functioning, and Physical Activity of People with Rett Syndrome-A Single-Cohort Study

BACKGROUND

Gross motor function in Rett syndrome (RTT) is always limited. The complex clinical picture typical of most people with RTT requires intensive and specific rehabilitation programs. Previous reports on remotely supervised motor activity programs suggested positive outcomes for this population. The current article describes the impact of a remote-supervised motor activity program carried out by family members of individuals with RTT on achieving rehabilitation goals and improving gross and fine motor functioning and daily physical activity.

METHODS

Forty subjects with RTT followed a three-month remotely supervised motor activity program carried out by their family members at home after a three-month baseline period. After the end of the intervention, a three-month wash-out period was implemented. Rehabilitation goal achievement, motor functioning, and level of daily physical activity were measured.

RESULTS

82.4% of rehabilitation goals were achieved or overachieved. Participants' motor functioning and physical activity significantly increased after the intervention (p ˂ 0.001). Improvements were maintained after the wash-out phase.

CONCLUSIONS

The proposed intervention was effective for people with RTT of various ages and severity levels. The results highlight the need for lifelong, individualized, daily based, and professionally supervised rehabilitation possibilities for individuals with RTT.

Intensive Postural and Motor Activity Program Reduces Scoliosis Progression in People with Rett Syndrome

Background: A scoliosis prevalence of 94% was reported in the population with Rett syndrome (RTT), with an annual progression rate of 14 to 21° Cobb which may result in pain, loss of sitting balance, deterioration of motor skills, and lung disfunction. This paper describes the efficacy of an intensive conservative individualized physical and postural activity program in preventing scoliosis curvature progression in patients with RTT. Methods: Twenty subjects diagnosed with RTT and scoliosis were recruited, and an individualized intensive daily physical activity program was developed for each participant. Each program was conducted for six months by participants’ primary caregivers in their daily living environment. Fortnightly remote supervision of the program implementation was provided by an expert therapist. Pre- and post-intervention radiographs and motor functioning were analyzed. Results: An averaged progression of +1.7° ± 8.7° Cobb, over one year (12.3 ± 3.5 months) was observed in our group, together with motor function improvements. A relation between curve progression and motor skill improvement was observed. Conclusions: The intervention prevented scoliosis progression in our group. The achievement of functional motor improvements could enable better body segment control and muscle balancing, with a protective effect on scoliosis progression. The intervention was effective for individuals with RTT across various ages and severity levels. Individual characteristics of each participant and the details of their activity program are described.

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

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

Epidemiology of Rett syndrome in Serbia: prevalence, incidence and survival

BACKGROUND

Rett syndrome (RTT) is a severe neurodevelopmental disorder that represents the second most common cause of mental retardation in females. However, incidence and prevalence of RTT are scarcely reported.

METHODS

A retrospective study included all patients with RTT diagnosed between 1981 and 2012 in Serbia. Estimation of incidence and prevalence was calculated on the basis of vital statistics reported by Statistical Office of Republic of Serbia.

RESULTS

From 1981 to 2012, RTT has been diagnosed in 102 girls in Serbia. Incidence of RTT in Serbia is estimated at 0.586:10,000 female live births. We estimated the prevalence of RTT in population of females younger than 19 years at 1:8,439. Death occurred in 19 patients (18.63%), with pneumonia as the most common cause. The lethal outcome by the age of 12 years could be expected for 11% of patients. The mean age at diagnosis was 3.5 years and we have confirmed a significant trend towards earlier dianosis during studied period.

CONCLUSIONS

Rett syndrome incidence in Serbia is in accordance with reports from other countries. Serbian RTT patients have increased risk for early death when compared to patients in more developed countries, most commonly due to pneumonia. There was significant trend towards early diagnosis of RTT in Serbia over recent decades.

Trends in the diagnosis of Rett syndrome in Australia

Modifications to diagnostic criteria and introduction of genetic testing have likely affected the pattern and timing of Rett syndrome diagnosis. The trends in incidence and prevalence of Rett syndrome in Australia were examined; the cumulative risk of a female being diagnosed was determined; and the impact of changes to diagnostic criteria and availability of genetic testing on these frequencies was investigated. The population-based Australian Rett Syndrome Database was used to identify a total of 349 verified Rett syndrome females born 1976-2006 and diagnosed 1982-2008. The proportion of female cases born and diagnosed per year and the cumulative risk of a diagnosis were determined. The median age of Rett syndrome diagnosis decreased from 4.5 y if diagnosed before 2000 to 3.5 y if diagnosed after 1999. The cumulative risk of diagnosis had almost doubled by 32 y of age [1/8,905 or 11.23 per 100,000 person-years (95% CI, 10.03-12.45)] in comparison with 5 y of age [1/15,361 or 6.51 per 100,000 person-years (95% CI, 5.65-7.39)]. Earlier age of diagnosis may result in families experiencing less stress and emotional strain compared with those with delayed diagnosis.

Spinal deformity and disability in patients with Rett syndrome

AIM

Rett syndrome is a neurodevelopmental disorder starting in early childhood with devastating consequences both on the brain and on systemic neurons. Scoliosis is a common complication in most of these patients. The aim of the study was to describe the prevalence of scoliosis, classify spinal deformity, and evaluate the association between disability and scoliosis in patients with Rett syndrome.

METHOD

Twenty-nine female patients, mean age 14 years 8 months (range 4 y 10 mo-33 y) were included. Outcome parameters were the Barthel Index for evaluation of function, pain, analgesics, and radiological evaluation of the spine including curve size (Cobb's method) and curve type. None of the patients had surgery before assessment.

RESULTS

Twenty-five (87%) patients had radiographically verified scoliosis. The median curve was 41° (range 15-77). The curve was classified as C-shaped (neuromuscular) in 16 patients and double curve-shaped in nine. Function was poorer in patients with C-shaped curve (p<0.01). Walking on a level surface (r=0.9) and the ability to ascend or descend stairs (r=0.8) were highly correlated with the Barthel Index. Curve size was moderately correlated with function (r=0.5).

INTERPRETATION

Function level in females with Rett syndrome measured according to the Barthel Index showed significant correlation to scoliosis curve type. A low score was associated with a C-shaped curve involving all of the spine and pelvis.

Rett syndrome: prevalence among Chinese and a comparison of MECP2 mutations of classic Rett syndrome with other neurodevelopmental disorders

Rett syndrome is an X-linked dominant neurodevelopmental disorder. Mutation of the methyl-CpG-binding protein 2 gene (MECP2) is present in up to 96% of patients with Rett syndrome. Eight mutations represent the hotspot of MECP2 mutations (R106W, R133C, T158M, R168X, R255X, R270X, R294X, and R306C) in patients with classic Rett syndrome. The prevalence and survival rate of Rett syndrome among Chinese women was investigated. The 8 hotspot mutations and the A140V mutation were also studied in 4 cohorts of Chinese children (n = 144) actively followed up in our university neurodevelopmental center with classic Rett syndrome (n = 5), autism spectrum disorder (n = 94), epileptic encephalopathy of unknown cause (n = 22), and nonsyndromal mental retardation (n = 23). The prevalence of Rett syndrome among female Chinese younger than 35 years in Hong Kong West is 0.57 (95% confidence interval, 0.15-0.98) per 10 000. Survival is 100.0% at 10 years and 87.5% at 25 years. Three hotspot mutations (R106W, R255X, and R306C) were found in 3 girls with classic Rett syndrome. No hotspot MECP2 mutations were found in the other 3 cohorts. Screening of MECP2 mutations is not worthwhile in Chinese children with pure cognitive, autistic, or unexplained epileptic disorders without other signs of Rett syndrome. In the early stage of developmental arrest before developmental regression, MECP2 screening might be useful for girls with unexplained epileptic encephalopathy before full-blown classic Rett syndrome is evident.

Rett syndrome in Australia: a review of the epidemiology

OBJECTIVE

To examine the prevalence, cumulative incidence, and survival in an Australian cohort with Rett syndrome (RTT).

STUDY DESIGN

The Australian Rett Syndrome Database is a longitudinal data collection that included 276 verified female cases at the end of 2004. Survival was calculated using the Kaplan-Meier product limit method, and cumulative incidence was determined using the complement of the Kaplan-Meier method.

RESULTS

Most cases (88.4%) have had MECP2 mutation testing, with positive results in 73%. The prevalence of RTT was .88 per 10,000 females in 5- to 18-year-olds, and the cumulative incidence was 1.09 per 10,000 females by 12 years of age. The cumulative incidence by the age of 5 years increased from .39 per 10,000 in the 1980 to 1984 cohort to .76 per 10,000 in birth cohorts beyond 1984. Survival was 77.8% at 25 years, compared with 99.96% survival in the Australian female population. Pneumonia (10/25) was the most common cause of death.

CONCLUSIONS

The availability of genetic testing has contributed to the changing pattern and timing of RTT diagnosis in Australia. Girls with RTT have worse survival compared with the general female population. When more data are available, it will be possible to evaluate the relationship between survival and specific MECP2 mutations.

Mutations of CDKL5 cause a severe neurodevelopmental disorder with infantile spasms and mental retardation

Rett syndrome (RTT) is a severe neurodevelopmental disorder caused, in most classic cases, by mutations in the X-linked methyl-CpG-binding protein 2 gene (MECP2). A large degree of phenotypic variation has been observed in patients with RTT, both those with and without MECP2 mutations. We describe a family consisting of a proband with a phenotype that showed considerable overlap with that of RTT, her identical twin sister with autistic disorder and mild-to-moderate intellectual disability, and a brother with profound intellectual disability and seizures. No pathogenic MECP2 mutations were found in this family, and the Xq28 region that contains the MECP2 gene was not shared by the affected siblings. Three other candidate regions were identified by microsatellite mapping, including 10.3 Mb at Xp22.31-pter between Xpter and DXS1135, 19.7 Mb at Xp22.12-p22.11 between DXS1135 and DXS1214, and 16.4 Mb at Xq21.33 between DXS1196 and DXS1191. The ARX and CDKL5 genes, both of which are located within the Xp22 region, were sequenced in the affected family members, and a deletion of nucleotide 183 of the coding sequence (c.183delT) was identified in CDKL5 in the affected family members. In a screen of 44 RTT cases, a single splice-site mutation, IVS13-1G-->A, was identified in a girl with a severe phenotype overlapping RTT. In the mouse brain, Cdkl5 expression overlaps--but is not identical to--that of Mecp2, and its expression is unaffected by the loss of Mecp2. These findings confirm CDKL5 as another locus associated with epilepsy and X-linked mental retardation. These results also suggest that mutations in CDKL5 can lead to a clinical phenotype that overlaps RTT. However, it remains to be determined whether CDKL5 mutations are more prevalent in specific clinical subgroups of RTT or in other clinical presentations.

Identification of MeCP2 mutations in a series of females with autistic disorder

Rett disorder and autistic disorder are both pervasive developmental disorders. Recent studies indicate that at least 80% of Rett Disorder cases are caused by mutations in the methyl-CpG-binding protein 2 (MeCP2) gene. Since there is some phenotypic overlap between autistic disorder and Rett disorder, we analyzed 69 females clinically diagnosed with autistic disorder for the presence of mutations in the MeCP2 gene. Two autistic disorder females were found to have de novo mutations in the MeCP2 gene. These data provide additional evidence of variable expression in the Rett disorder phenotype and suggest MeCP2 testing may be warranted for females presenting with autistic disorder.

Behaviour problems in adult women with Rett syndrome

BACKGROUND

Despite considerable interest in the genetic, physical and neurological aspects of Rett syndrome (RS), there have been few studies of associated behavioural and emotional features. Furthermore, few case studies or surveys have included adult women with RS. The main aim of the present study was to compare behaviour problems in a sample of women with RS against data from normative samples.

METHODS

The primary carers of 50 women with RS completed the community version of the Aberrant Behavior Checklist.

RESULTS

Women with RS were rated as having lower levels of irritability, hyperactivity and inappropriate speech behaviours than normative samples of adults with intellectual disability.

CONCLUSIONS

A number of factors may affect the presentation of behaviour problems in women with RS (e.g. cognitive impairments or physical disabilities). Therefore, more research is needed in order to generate information about the behavioural phenotype of RS. The implications of the present data for future research are also discussed.

Importance of Rett syndrome in child neurology

The syndrome of brain atrophy in girls described by Andreas Rett in 1966 [Rett, Wien Klin Wochenschr, 1966;116:723-726] was brought to the attention of the English-speaking world by Hagberg et al. in 1983 [Hagberg et al., Ann Neurol, 1983;14:471-479]. Four clinical stages after the age of 6 months were described in classical cases of Rett syndrome (RS), namely early onset stagnation at 6 months to 1(1/2) years, the rapid destructive stage at 1-3 years, the pseudo-stationary stage from pre-school to school years, and the late motor deterioration stage at 15-30 or more years. The rapid destructive stage causes profound dementia with loss of speech and hand skills, stereotypic movements, ataxia, apraxia, irregular breathing with hyperventilation while awake, and frequently seizures. Most cases are isolated in their families, apart from identical twins. However, linkage studies in rare familial cases suggested a critical region at Xq28. In 1999 American investigators found several mutations in the X-linked gene MECP2 encoding Methyl-CpG-binding protein 2 in a proportion of Rett patients. The protein MeCP2 can bind methylated DNA and when mutated may interfere with transcriptional silencing of other genes and result in abnormal chromatin assembly. Many different mutations of the protein are being studied in humans and in mice. Neuropathological studies have shown decreased brain growth and decreased size of individual neurons, with thinned dendrites in some cortical layers, and abnormalities in substantia nigra, suggestive of deficient synaptogenic development, probably starting before birth. Electrophysiology demonstrates progressively abnormal electroencephalograms (EEG) in the first three stages of the syndrome, with some subsequent improvement and occurrence of pseudoseizures. Neurometabolic factors are discussed in detail, particularly reduced levels of dopamine, serotonin, noradrenaline and choline acetyltransferase (ChAT) in brain, also estimation of nerve growth factors, endorphin, substance P, glutamate and other amino acids and their receptor levels. Autonomic dysfunction is described, particularly reduced vagal and overactive sympathetic activity. Neuro-imaging may be required for further investigation, as shown in the differential diagnosis.

Rett syndrome: review of biological abnormalities

The Rett syndrome (RS) is a peculiar, sporadic, atrophic disorder, almost entirely confined to females. After the first six months of life there is developmental slowing with reduced communication and head growth for about one year. This is followed by a rapid destructive stage with severe dementia and loss of hand skills (with frequent hand wringing), apraxia and ataxia, autistic features and irregular breathing with hyperventilation. Seizures often supervene. Subsequently there is some stabilization in a pseudo-stationary stage during the preschool to school years, associated with more emotional contact but also abnormalities of the autonomic and skeletal systems. After the age of 15-20 years, a late motor deterioration occurs with dystonia and frequent spasticity but seizures become milder. RS has generally been considered an X-linked disorder in which affected females represent a new mutation, with male lethality. Linkage studies suggested a critical region at Xq28. In 1999, mutations in the gene MECP2 encoding X-linked methyl cytosine-binding protein 2 (MeCP2) were found in a proportion of Rett girls. This protein can bind methylated DNA. Analyses are leading to much further investigation of mutants and their effects on genes. Neuropathological and electrophysiological studies of RS are described. Description of neurometabolic factors includes reduced levels of dopamine, serotonin, noradrenaline and choline acetyltransferase (ChAT) in brain, also estimation of nerve growth factors, endorphin, substance P, glutamate and other amino acids and their receptor levels. The results of neuroimaging are surveyed, including volumetric magnetic resonance imaging (MRI) and positron emission tomography (PET).

Using genetic epidemiology to study Rett syndrome: the design of a case-control study

Rett syndrome is a neurological disorder that is seen almost exclusively in females. Although generally considered to have a genetic basis, the underlying mechanism remains obscure. One favoured hypothesis is that the syndrome is an X-linked dominant disorder, lethal or non-expressed in males. Genealogical research has also suggested that the mode of transmission in Rett syndrome may involve a premutation which over several generations is converted to a full mutation. Geographical clustering has been reported, and it has also been proposed that Rett syndrome is a clinically variable condition and that other neurological disorders may be occurring more commonly in families with Rett syndrome. Other studies have found an apparent increase in intellectual disability and seizures in the extended families of girls with Rett syndrome. The science of genetic epidemiology can be used to identify familial aggregation, which is the clustering of a disorder within a family. We have used a case-control study design to investigate both fetal wastage and familial aggregation of other disorders in families of girls with Rett syndrome. The Australian Rett Syndrome Database provided the source of cases, and control probands were girls of a similar age with normal development. This paper describes the methodology for a case-control study of this rare condition using pedigree data and discusses issues in the collection and evaluation of such data. The use of a control population is an important feature. Both the strengths and the shortcomings of our design are identified, and recommendations are made for future research.

Molecular approaches to the Rett syndrome gene

Rett syndrome is a neurodevelopmental disorder affecting 1 in 10,000 to 15,000 females worldwide. Apparently normal at birth, girls with Rett syndrome undergo developmental regression and acquire a neurologic and behavioral profile that has been used to define diagnostic criteria for the disorder. Neurochemical and anatomic alterations indicate that Rett syndrome appears to result from an arrest of normal neuronal maturation. Although Rett syndrome generally occurs sporadically, rare familial recurrences indicate a genetic basis for the disorder. Data from familial recurrences are consistent with an X-linked dominant locus causing the classic phenotype in female patients and a distinct, more severe phenotype in hemizygous male patients. Exclusion mapping data from rare kindreds with recurrent Rett syndrome localize the gene to the distal long arm of the X chromosome (Xq27.3-Xqter).

Familial aggregation in Rett syndrome: what is the evidence for clustering of other disorders in families of affected girls?

Rett syndrome is a neurodevelopmental disorder of unknown cause which affects girls almost exclusively. Apparently normal development in the first year of life is usually followed by loss of skills and the development of stereotypic hand movements. This study has used genetic epidemiological methods including a case control design to examine the evidence for aggregation of other disorders in families of girls with Rett syndrome. In one family there were two sisters with a condition consistent with Rett syndrome. Intellectual disability was not reported more commonly in case families (P = 0.46). However, "learning problems" were slightly commoner (P = 0.05) especially in the parental generation (P = 0.02) and these findings warrant further investigation. Mental illness and seizures were not reported at an increased prevalence. However, we would recommend the use of other strategies to collect information about psychiatric illness. Spinal curvature was reported more commonly in case families (P = 0.07) but no mechanism for clinical verification of this was included in the study. There was an apparent increase in bowel problems in the parents (P = 0.04). The major weaknesses of our study were our inability to validate any diagnosis clinically and the lack of power (due to the comparative rarity of the outcomes). The strengths are that we have been able to collect pedigree data on the families of a substantial proportion of a total population of girls with Rett syndrome and to collect comparative data from a control population. Our reported findings warrant further investigation in a larger study.