Multi-disciplinary clinical study of Smith-Magenis syndrome (deletion 17p11.2)

Overlapping hearing and communication profiles for the deletion and the RAI1 variant form of Smith-Magenis Syndrome (SMS)

Smith-Magenis syndrome (SMS), a rare, genetically linked complex developmental disorder is associated with hearing loss and delays in speech-language development. Approximately 70 % of those with SMS have a genetic deletion within chromosome 17p11.2 and 10 % have a single gene mutation in the same area, known as the RAI1 variant form of SMS. Previous studies presented preliminary comparisons of the phenotype of those with deletion versus the mutation form of SMS, but none focused on hearing, speech-language, and communication profiles. The current study examined patient registry data and compared two groups of individuals with SMS to determine if genetic differences influence the communication phenotype and to determine the importance of the RAI1 gene in hearing, speech, and language abilities in children. Speech-language and hearing data from the international SMS Patient Registry for 33 subjects with SMS were analyzed: 23 with a genetic deletion (SMS (del)) and 10 with an RAI1 mutation (SMS (RAI1)). Hearing status, otopathology findings, early speech-language milestones, mode of communication, intelligibility, vocal quality, language abilities, and literacy skills were analyzed. There were small differences between the groups for hearing status, otopathological findings, mode of communication, voice quality, intelligibility, speech-language abilities, and literacy. Overlap in the speech-language phenotype between groups confirms previous hypotheses that suggest haploinsufficiency of the RAI1 gene is responsible for the SMS phenotype and that the RAI1 gene is critical for speech-language development. Future studies should include direct testing of receptive and expressive language abilities, including analyses of language samples, with larger groups of individuals to replicate and extend the current findings.

Case Report: A Case of a Patient with Smith-Magenis Syndrome and Early-Onset Parkinson's Disease

Smith-Magenis Syndrome (SMS) is a rare genetic disorder, characterized by intellectual disability (ID), behavioral impairments, and sleep disturbances, as well as multiple organ anomalies in some affected individuals. The syndrome is caused by a deletion in the chromosome band around 17p11.2, including the Retinoic Acid Induced 1 (RAI1) gene, a multifaceted transcriptional regulator that modulates the expression of genes involved in cellular proliferation and neurodevelopment. This gene has a positive role in regulating BDNF and, importantly, affects several cell mechanisms and pathways such as the nigro-striatal pathway, which is crucial for motor function. Parkinson's disease (PD) is one of the most common neurodegenerative diseases in older populations. It is characterized by various physical symptoms including tremors, loss of balance, bradykinesia, and a stooping posture. We present a case study of a patient diagnosed with both SMS and early-onset PD (at the age of 49). The association between both conditions is as yet ambiguous. Genome-wide association studies (GWAS) implicate an association between the RAI1 gene and PD. Similarly, the co-existence of both SMS and PD in the patient suggests a possible association between RAI1 copy number variations (CNVs) and PD, further indicating that RAI1 has strong implications for PD pathogenesis. Our results suggest that RAI1 CNVs and the pathophysiology of PD may be related, underscoring the need for further research in this field. Therefore, caregivers of SMS patients should pay careful attention to the possibility of their patients developing EOPD and should consider starting treatment for PD as soon as the first symptoms appear.

Blind to the perils of pursuing food: Behaviors of individuals with Smith-Magenis Syndrome

Purpose

Discrepancies exist between the need to lock food away and satiety scores in the Smith-Magenis syndrome (SMS) population. This study sought to uncover food-related behaviors within this unique group of individuals.

Methods

Caregivers (N = 24) representing 21 individuals with SMS, recruited from the Parents and Researchers Interested in SMS national meeting and social media platforms, participated in semistructured interviews. Interviews were digitally recorded, transcribed verbatim, coded, and analyzed using hybrid thematic analysis.

Results

This study identified a global theme of "Blind to the perils while pursuing their goals," supported by 5 organizing themes: (1) Biology-impacting behaviors, (2) Need for personalized strategies, (3) Controlling food experiences, (4) Need for parents to orchestrate life, and (5) Surprising resourcefulness. Subthemes within these organizing themes highlighted that individuals with SMS have unique food-related behaviors and often fixate on certain types of foods. Their constant obsession with food for many of them is driven by hunger, obsessive characteristics, a need for autonomy, and a need for fairness. Caregivers must put multiple guardrails in place and remain constantly vigilant to prevent overeating in these individuals.

Conclusion

Individuals with SMS often perseverate on food and display unique food-related behaviors. Treating obesity in this population is likely to be ineffective without multicomponent, individualized strategies. Additionally, research in this population will likely require targeted instruments for the SMS population to more clearly define the underlying etiologies and to track changes over time in therapeutic trials.

Identification of Smith-Magenis syndrome cases through an experimental evaluation of machine learning methods

This research work introduces a novel, nonintrusive method for the automatic identification of Smith-Magenis syndrome, traditionally studied through genetic markers. The method utilizes cepstral peak prominence and various machine learning techniques, relying on a single metric computed by the research group. The performance of these techniques is evaluated across two case studies, each employing a unique data preprocessing approach. A proprietary data "windowing" technique is also developed to derive a more representative dataset. To address class imbalance in the dataset, the synthetic minority oversampling technique (SMOTE) is applied for data augmentation. The application of these preprocessing techniques has yielded promising results from a limited initial dataset. The study concludes that the k-nearest neighbors and linear discriminant analysis perform best, and that cepstral peak prominence is a promising measure for identifying Smith-Magenis syndrome.

Speech, Language, Hearing, and Otopathology Results From the International Smith-Magenis Syndrome Patient Registry

PURPOSE

Smith-Magenis syndrome (SMS), a rare, genetically linked complex developmental disorder caused by a deletion or mutation within chromosome 17p11.2, is associated with delays in speech-language development, otopathology, and hearing loss, yet previous studies lack comprehensive descriptions of hearing and communication profiles. Here, analyses of patient registry data expand what is known about speech, language, hearing, and otopathology in SMS.

METHOD

International speech-language and hearing registry survey data for 82 individuals with SMS were analyzed using descriptive and inferential statistics. Hearing loss, history of otitis media and pressure equalization (PE) tubes, communication mode, expressive/receptive language, and vocal quality were analyzed for all subjects and subjects grouped by age. Statistical methods included descriptive statistics and Pearson's chi-square tests of independence to test for differences between age groups for each variable of interest. Association analyses included Pearson's correlations.

RESULTS

Hearing and otological analyses revealed that 35% of subjects had hearing loss, 66% had a history of otitis media, and 62% had received PE tubes. Speech-language analyses revealed that 60% of subjects communicated using speech, 79% began speaking words at/after 24 months of age, 92% combined words at/after 36 months, and 41% used sign language before speech. There was a significant association between the age that first words were spoken and the age that PE tubes were first placed. Communication strengths noted in more than 40% of subjects included social interest, humor, and memory for people, past events, and/or facts.

CONCLUSIONS

Significant delays and impairment in speech-language were common, but the majority of those with SMS communicated using speech by age 6 years. Age was a significant factor for some aspects of hearing loss and communication. Neither hearing loss nor otitis media exacerbated language impairment. These results confirm and extend previous findings about the nature of speech, language, hearing, and otopathology in those with SMS.

Psychiatric and neurological manifestations in adults with Smith-Magenis syndrome: A scoping review

Smith-Magenis syndrome (SMS) is a neurodevelopmental disorder caused by a 17p11.2 deletion or a pathogenic variant of the RAI1 gene, which lies within the 17p11.2 region. Various psychiatric and neurological disorders have been reported in SMS, with most literature focusing on children and adolescents. To provide an overview of the current knowledge on this topic in adults with SMS, we performed a comprehensive scoping review of the relevant literature. Our findings suggest that many manifestations that are common in childhood persist into adulthood. Neuropsychiatric manifestations in adults with SMS include intellectual disability, autism spectrum- and attention deficit hyperactivity disorder-related features, self-injurious and physical aggressive behaviors, sleep-wake disorders, and seizures. Findings of this review may facilitate optimization of management strategies in adults with SMS, and may guide future studies exploring late-onset psychiatric and neurological comorbidities in SMS.

Sleep and Circadian Disturbances in Children With Neurodevelopmental Disorders

Sleep problems are highly prevalent in those with neurodevelopmental disorders (NDDs). We propose this is secondary to multiple factors that directly and indirectly negatively impact sleep and circadian processes in those with NDDs, which in turn, further perturbs development, resulting in a "developmental and sleep/circadian-related encephalopathy." In this review, we discuss select NDDs with known or suspected sleep and circadian phenotypes. We also highlight important considerations when evaluating and treating sleep and circadian disorders in these populations.

Association analysis between chromosomal abnormalities and fetal ultrasonographic soft markers based on 15,263 fetuses

BACKGROUND

Soft markers are common prenatal ultrasonographic findings that indicate an increased risk for fetal aneuploidy. However, the association between soft markers and pathogenic or likely pathogenic copy number variations is still unclear, and clinicians lack clarity on which soft markers warrant a recommendation for invasive prenatal genetic testing of the fetus.

OBJECTIVE

This study aimed to provide guidance on ordering prenatal genetic testing for fetuses with different soft markers and to elucidate the association between specific types of chromosomal abnormalities and specific ultrasonographic soft markers.

STUDY DESIGN

Low-pass genome sequencing was performed for 15,263 fetuses, including 9123 with ultrasonographic soft markers and 6140 with normal ultrasonographic findings. The detection rate of pathogenic or likely pathogenic copy number variants among fetuses with various ultrasonographic soft markers were compared with that of fetuses with normal ultrasonography. The association of soft markers with aneuploidy and pathogenic or likely pathogenic copy number variants were investigated using Fisher exact tests with Bonferroni correction.

RESULTS

The detection rate of aneuploidy and pathogenic or likely pathogenic copy number variants was 3.04% (277/9123) and 3.40% (310/9123), respectively, in fetuses with ultrasonographic soft markers. An absent or a hypoplastic nasal bone was the soft marker in the second trimester with the highest diagnostic rate for aneuploidy of 5.22% (83/1591) among all isolated groups. Four types of isolated ultrasonographic soft markers, namely a thickened nuchal fold, single umbilical artery, mild ventriculomegaly, and absent or hypoplastic nasal bone, had higher diagnostic rates for pathogenic or likely pathogenic copy number variants (P<.05; odds ratio, 1.69-3.31). Furthermore, this study found that the 22q11.2 deletion was associated with an aberrant right subclavian artery, whereas the 16p13.11 deletion, 10q26.13-q26.3 deletion, and 8p23.3-p23.1 deletion were associated with a thickened nuchal fold, and the 16p11.2 deletion and 17p11.2 deletion were associated with mild ventriculomegaly (P<.05).

CONCLUSION

Ultrasonographic phenotype-based genetic testing should be considered in clinical consultations. Copy number variant analysis is recommended for fetuses with an isolated thickened nuchal fold, a single umbilical artery, mild ventriculomegaly, and an absent or a hypoplastic nasal bone. A comprehensive definition of genotype-phenotype correlations in aneuploidy and pathogenic or likely pathogenic copy number variants could provide better information for genetic counseling.

Metabolic Profile of Patients with Smith-Magenis Syndrome: An Observational Study with Literature Review

Background: Smith-Magenis syndrome (SMS) is caused by either interstitial deletions in the 17p11.2 region or pathogenic variants in the RAI1 gene and is marked by a distinct set of physical, developmental, neurological, and behavioral features. Hypercholesterolemia has been described in SMS, and obesity is also commonly found. Aim: To describe and characterize the metabolic phenotype of a cohort of SMS patients with an age range of 2.9-32.4 years and to evaluate any correlations between their body mass index and serum lipids, glycated hemoglobin (HbA1c), and basal insulin levels. Results: Seven/thirty-five patients had high values of both total cholesterol and low-density lipoprotein cholesterol; 3/35 had high values of triglycerides; none of the patients with RAI1 variants presented dyslipidemia. No patients had abnormal fasting glucose levels. Three/thirty-five patients had HbA1c in the prediabetes range. Ten/twenty-two patients with 17p11.2 deletion and 2/3 with RAI1 variants had increased insulin basal levels. Three/twenty-three patients with the 17p11.2 deletion had prediabetes. Conclusion: Our investigation suggests that SMS 'deleted' patients may show a dyslipidemic pattern, while SMS 'mutated' patients are more likely to develop early-onset obesity along with hyperinsulinism.

The genetics of autism spectrum disorder in an East African familial cohort

Autism spectrum disorder (ASD) is a group of complex neurodevelopmental conditions affecting communication and social interaction in 2.3% of children. Studies that demonstrated its complex genetic architecture have been mainly performed in populations of European ancestry. We investigate the genetics of ASD in an East African cohort (129 individuals) from a population with higher prevalence (5%). Whole-genome sequencing identified 2.13 million private variants in the cohort and potentially pathogenic variants in known ASD genes (including CACNA1C, CHD7, FMR1, and TCF7L2). Admixture analysis demonstrated that the cohort comprises two ancestral populations, African and Eurasian. Admixture mapping discovered 10 regions that confer ASD risk on the African haplotypes, containing several known ASD genes. The increased ASD prevalence in this population suggests decreased heterogeneity in the underlying genetic etiology, enabling risk allele identification. Our approach emphasizes the power of African genetic variation and admixture analysis to inform the architecture of complex disorders.

Relationships between food-related behaviors, obesity, and medication use in individuals with Smith-Magenis syndrome

BACKGROUND

Smith-Magenis syndrome (SMS) is a complex neurodevelopmental disorder that includes obesity and food-seeking/satiety-related behaviors.

AIMS

This study examined associations between food-related/hyperphagic behaviors, weight, and medication use in individuals with SMS.

METHODS/PROCEDURES

Caregivers of individuals with SMS in the Parents and Researchers Interested in SMS (PRISMS) Patient Registry completed a demographic/medication questionnaire, the Hyperphagia Questionnaire for Clinical Trials, and the Food Related Problems Questionnaire.

OUTCOMES/RESULTS

Among 49 participants (M_age = 16.41 ± 12.73 years, range = 4-69 years, 55% girls/women), individuals with SMS with overweight/obesity (n = 22) had worse overall food-related problems including greater impaired satiety (p < 0.05), maladaptive eating behaviors (p < 0.05), inappropriate response (p < 0.01), and hyperphagia (p < 0.01) compared to individuals of normal/underweight (n = 27). Those taking anti-depressants/anxiolytics (n = 16) had greater maladaptive eating behaviors (p < 0.05), hyperphagic behaviors (p < 0.05), and hyperphagic severity (p < 0.05) than those not taking anti-depressants/anxiolytics (n = 33). Boys/men with SMS had greater maladaptive eating behaviors (p < 0.05), inappropriate response (p < 0.05), and hyperphagic drive (p < 0.01) than girls/women with SMS.

CONCLUSIONS/IMPLICATIONS

Maladaptive food-related behaviors were higher in individuals with SMS with overweight/obesity, taking anti-depressants/anxiolytics, or who were male. Medications in this population should be chosen with weight-related side effects in mind.

Prenatal Socioeconomic Disadvantage and Epigenetic Alterations at Birth Among Children Born to White British and Pakistani Mothers in the Born in Bradford Study

Prenatal socioeconomic disadvantage (SD) has been linked to DNA methylation (DNAm) in adulthood, but whether such epigenetic alterations are present at birth remains unclear. We carried out an epigenome-wide analysis of the association between several measures of individual- and area-level prenatal SD and DNAm assessed in neonatal cord blood via the Infinium EpicBeadChip among offspring born to mothers of White British (N = 455) and Pakistani (N = 493) origin in the Born in Bradford Study. Models were adjusted for mother's age, ethnicity, and education level as well as cell-type fractions and then for maternal health behaviours and neonate characteristics, and last, stratified by mother's ethnicity. P-values were corrected for multiple testing and a permutation-based approach was used to account for small cell sizes. Among all children, housing tenure (owning versus renting) as well as father's occupation (manual versus non-manual) were each associated with DNAm of one CpG site and index of multiple deprivation (IMD) was associated with DNAm of 11 CpG sites. Among children born to White British mothers, father's occupation (student or unemployed versus non-manual) was associated with DNAm of 1 CpG site and IMD with DNAm of 3 CpG sites. Among children born to Pakistani mothers, IMD was associated with DNAm of 1 CpG site. Associations were largely unchanged after further adjustment for maternal health behaviours or neonate characteristics and remained statistically significant. Our findings suggest that individual- and area-level prenatal SD may shape alterations to the neonatal epigenome, but associations vary across ethnic groups.

Comparison of methylation episignatures in KMT2B- and KMT2D-related human disorders

Aim & methods: To investigate peripheral blood methylation episignatures in KMT2B-related dystonia (DYT-KMT2B), the authors undertook genome-wide methylation profiling of ∼2 M CpGs using a next-generation sequencing-based assay and compared the findings with those in controls and patients with KMT2D-related Kabuki syndrome type 1 (KS1). Results: A total of 1812 significantly differentially methylated CpG positions (false discovery rate < 0.05) were detected in DYT-KMT2B samples compared with controls. Multi-dimensional scaling analysis showed that the 10 DYT-KMT2B samples clustered together and separately from 29 controls and 10 with pathogenic variants in KMT2D. The authors found that most differentially methylated CpG positions were specific to one disorder and that all (DYT-KMT2B) and most (Kabuki syndrome type 1) methylation alterations in CpG islands were gain of methylation events. Conclusion: Using sensitive methylation profiling methodology, the authors replicated recent reports of a methylation episignature for DYT-KMT2B. These findings will facilitate the development of episignature-based assays to improve diagnostic accuracy.

Smith Magenis syndrome: First case of congenital heart defect in a patient with Rai1 mutation

Smith Magenis syndrome (SMS) is a rare neurobehavioral disorder caused by 17p11.2 microdeletion encompassing Retinoic Acid-Induced 1 (RAI1) gene (90% of cases) or by RAI1 point mutation (10% of cases). The neuropsychological phenotype of individuals with 17p11.2 deletion and in those with RAI1 variants mostly overlaps. However, cardiac defects have been described only in patients with a deletion so far. Here, we present the first case of a patient affected by SMS caused by RAI1 variant in whom a severe congenital pulmonary valve stenosis was diagnosed at birth, requiring trans catheter dilatation in the first month of life. This case expands the phenotypic spectrum associated with RAI1 variants in SMS, describing a previously unreported association with a congenital heart disease.

Smith-Magenis Syndrome—Clinical Review, Biological Background and Related Disorders

Smith-Magenis syndrome (SMS) is a complex genetic disorder characterized by distinctive physical features, developmental delay, cognitive impairment, and a typical behavioral phenotype. SMS is caused by interstitial 17p11.2 deletions (90%), encompassing multiple genes and including the retinoic acid-induced 1 gene (RAI1), or by pathogenic variants in RAI1 itself (10%). RAI1 is a dosage-sensitive gene expressed in many tissues and acting as transcriptional regulator. The majority of individuals exhibit a mild-to-moderate range of intellectual disability. The behavioral phenotype includes significant sleep disturbance, stereotypes, maladaptive and self-injurious behaviors. In this review, we summarize current clinical knowledge and therapeutic approaches. We further discuss the common biological background shared with other conditions commonly retained in differential diagnosis.

Caregivers' experience of sleep management in Smith-Magenis syndrome: a mixed-methods study

BACKGROUND

Smith-Magenis syndrome (SMS) is a rare genetic syndrome associated with a unique profile of early morning waking and daytime sleepiness. Children with SMS evidence high rates of self-injury and aggression and have a preference for adult over peer attention, with strong motivation to interact with a particular caregiver. In addition, people with SMS have lower adaptive functioning skills relative to cognitive abilities and demonstrate high levels of impulsivity. Taken together, these factors may result in individuals being awake overnight requiring vigilant caregiver supervision. Despite these complexities, no study has described the strategies caregivers take to keep their children with SMS safe overnight or considered the impact of these experiences on caregivers or the wider family.

METHODS

The current study used a mixed-methods approach to consider sleep management strategies and challenges for caregivers of people with SMS at different ages. Caregivers completed an international online survey about sleep management and related difficulties, use of interventions and access to services and support. Semi-structured interviews were conducted with 14 caregivers in the UK to increase understanding of caregiver experiences and priorities for change in the UK context. Interviews were transcribed verbatim and coded using thematic analysis.

RESULTS

Evidence from the online survey (n = 40) revealed wide-ranging impacts of poor sleep on the person with SMS and the wider family. Only 5% of caregivers reported that the sleep problems had no impact on their child, and 76% reported a moderately or extremely significant impact on themselves. For some individual caregivers, sleep management difficulties improved over time whereas for others no change was reported. Weekly respite emerged as the ideal provision for 49% of caregivers, although only 14% had access to this. The majority of caregivers (54%) received no respite. Thematic analysis of qualitative interviews revealed interactions between aspects of the behavioural phenotype of SMS which may contribute to complex and unusual presentations in relation to sleep management and safety.

CONCLUSIONS

Caregivers' priorities for sleep management and support were delineated, with key implications for services in terms of the use of SMS-sensitive strategies and respite provision.

Sleep and violence perpetration: A review of biological and environmental substrates

Violence is a worldwide societal burden that negatively impacts individual health, wellbeing and economic development. Evidence suggests a bidirectional relationship between sleep changes and violence. This review details, evaluates and discusses the biological and demographic substrates linking sleep and violence perpetration, and summarizes the overlap of brain areas, functional neuronal systems and genetic features involved, not including violent behaviours during sleep. Knowledge on the biological variables that affect the individual's susceptibility to violent behaviour may have implications for criminology, management of detentions and rehabilitation strategies.

Smith-magenis syndrome: A rare case report

Smith-Magenis syndrome is a rare genetic disorder involving multiple body systems, along with mental retardation and sleep disturbances. It is attributed to micro deletion at 17p11.2 chromosome region encoding for RAI1 gene. This article presents a case report of a 7-year-old patient having this rare syndrome along with his genetic analysis.

Tasimelteon safely and effectively improves sleep in Smith-Magenis syndrome: a double-blind randomized trial followed by an open-label extension

Purpose

To assess the efficacy of tasimelteon to improve sleep in Smith–Magenis syndrome (SMS).

Methods

A 9-week, double-blind, randomized, two-period crossover study was conducted at four US clinical centers. Genetically confirmed patients with SMS, aged 3 to 39, with sleep complaints participated in the study. Patients were assigned to treatment with tasimelteon or placebo in a 4-week crossover study with a 1-week washout between treatments. Eligible patients participated in an open-label study and were followed for >3 months.

Results

Improvement of sleep quality (DDSQ50) and total sleep time (DDTST50) on the worst 50% of nights were primary endpoints. Secondary measures included actigraphy and behavioral parameters. Over three years, 52 patients were screened, and 25 patients completed the randomized portion of the study. DDSQ50 significantly improved over placebo (0.4, p = 0.0139), and DDTST50 also improved (18.5 minutes, p = 0.0556). Average sleep quality (0.3, p = 0.0155) and actigraphy-based total sleep time (21.1 minutes, p = 0.0134) improved significantly, consistent with the primary outcomes. Patients treated for ≥90 days in the open-label study showed persistent efficacy. Adverse events were similar between placebo and tasimelteon.

Conclusion

Tasimelteon safely and effectively improved sleep in SMS.

A cross-comparison of cognitive ability across 8 genomic disorders

Genomic disorders result from rearrangement of the human genome. Most genomic disorders are caused by copy number variants (CNV), deletions or duplications of several hundred kilobases. Many CNV loci are associated with autism, schizophrenia, and most commonly, intellectual disability (ID). However, there is little comparison of cognitive ability measures across these CNV disorders. This study aims to understand whether existing data can be leveraged for a cross-comparison of cognitive ability among multiple CNV. We found there is a lack of harmonization among assessment instruments and little standardization for reporting summary data across studies. Despite these limitations, we identified a differential impact of CNV loci on cognitive ability. Our data suggest that future cross-comparisons of CNV disorders will reveal meaningful differences across the phenotypic spectrum, especially if standardized phenotypic assessment is achieved.

Acoustic Analysis of Phonation in Children With Smith-Magenis Syndrome

Complex simultaneous neuropsychophysiological mechanisms are responsible for the processing of the information to be transmitted and for the neuromotor planning of the articulatory organs involved in speech. The nature of this set of mechanisms is closely linked to the clinical state of the subject. Thus, for example, in populations with neurodevelopmental deficits, these underlying neuropsychophysiological procedures are deficient and determine their phonation. Most of these cases with neurodevelopmental deficits are due to a genetic abnormality, as is the case in the population with Smith–Magenis syndrome (SMS). SMS is associated with neurodevelopmental deficits, intellectual disability, and a cohort of characteristic phenotypic features, including voice quality, which does not seem to be in line with the gender, age, and complexion of the diagnosed subject. The phonatory profile and speech features in this syndrome are dysphonia, high f0, excess vocal muscle stiffness, fluency alterations, numerous syllabic simplifications, phoneme omissions, and unintelligibility of speech. This exploratory study investigates whether the neuromotor deficits in children with SMS adversely affect phonation as compared to typically developing children without neuromotor deficits, which has not been previously determined. The authors compare the phonatory performance of a group of children with SMS (N = 12) with a healthy control group of children (N = 12) matched in age, gender, and grouped into two age ranges. The first group ranges from 5 to 7 years old, and the second group goes from 8 to 12 years old. Group differences were determined for two forms of acoustic analysis performed on repeated recordings of the sustained vowel /a/ F1 and F2 extraction and cepstral peak prominence (CPP). It is expected that the results will enlighten the question of the underlying neuromotor aspects of phonation in SMS population. These findings could provide evidence of the susceptibility of phonation of speech to neuromotor disturbances, regardless of their origin.

Smith-Magenis syndrome: Report of morphological and new functional cardiac findings with review of the literature

Smith-Magenis syndrome (SMS) is a genetic disorder characterized by multiple congenital anomalies, sleep disturbance, behavioral impairment, and intellectual disability. Its genetic cause has been defined as an alteration in the Retinoic Acid-Induced 1 gene. Cardiac anomalies have been reported since the first description of this condition in patients with 17p11.2 deletion. Variable cardiac defects, including ventricular septal defects, atrial septal defects, tricuspid stenosis, mitral stenosis, tricuspid and mitral regurgitation, aortic stenosis, pulmonary stenosis, mitral valve prolapse, tetralogy of Fallot, and total anomalous pulmonary venous connection, have been anecdotally reported and systematic case series are still lacking. Herein, we define the spectrum of the cardiac phenotype and describe for the first time the cardiac function in a large cohort of pediatric patients with SMS. Revision of the literature and correlations between genotype and cardiac phenotype was performed.

Smith-Magenis syndrome: Clinical and behavioral characteristics in a large retrospective cohort

Smith-Magenis syndrome (SMS), characterized by dysmorphic features, neurodevelopmental disorder, and sleep disturbance, is due to an interstitial deletion of chromosome 17p11.2 (90%) or to point mutations in the RAI1 gene. In this retrospective cohort, we studied the clinical, cognitive, and behavioral profile of 47 European patients with SMS caused by a 17p11.2 deletion. We update the clinical and neurobehavioral profile of SMS. Intrauterine growth was normal in most patients. Prenatal anomalies were reported in 15%. 60% of our patients older than 10 years were overweight. Prevalence of heart defects (6.5% tetralogy of Fallot, 6.5% pulmonary stenosis), ophthalmological problems (89%), scoliosis (43%), or deafness (32%) were consistent with previous reports. Epilepsy was uncommon (2%). We identified a high prevalence of obstipation (45%). All patients had learning difficulties and developmental delay, but ID range was wide and 10% of patients had IQ in the normal range. Behavioral problems included temper tantrums and other difficult behaviors (84%) and night-time awakenings (86%). Optimal care of SMS children is multidisciplinary and requires important parental involvement. In our series, half of patients were able to follow adapted schooling, but 70% of parents had to adapt their working time, illustrating the medical, social, educative, and familial impact of having a child with SMS.

Adrenocorticotropic Hormone Therapy Improved Spasms and Sleep Disturbance in Smith-Magenis Syndrome: A Case Report

Smith-Magenis syndrome (SMS) is a complex disorder characterized by variable mental retardation, sleep disturbances, craniofacial and skeletal anomalies, self-injurious and attention-seeking behaviors, and speech and motor delays. The case of a 14-month-old girl with SMS who was experiencing spasm clusters and sleep disturbances with sleep-wake intervals of 1.5 to 2 h persisting from the neonatal period was examined. The patient's spasms stopped and interictal electroencephalography did not show epileptic discharges after undergoing a high-dose adrenocorticotropic hormone (ACTH) therapy. Moreover, the patient's sleep cycle stabilized 1 month after receiving the ACTH therapy. Dramatic reductions in the patient's self-injurious behaviors were also noted. At 1 year following ACTH treatment, the patient's improved sleep was maintained. High-dose ACTH treatment was considered to contribute to the normal adaptation of the hypothalamic-pituitary-adrenal axis by regulating the release of corticotropin-releasing hormone, resulting in improvement of the patient's infantile spasms and sleep disturbances.

Voice Characteristics in Smith–Magenis Syndrome: An Acoustic Study of Laryngeal Biomechanics

Smith–Magenis syndrome (SMS) is a rare genetic disease characterized by intellectual disability, serious behavior disorders, neurodevelopment delay, and speech and language disorders. An acoustic and biomechanical analysis of the voice of SMS young adults was carried out due to (a) the close relationship between the laryngeal biomechanics and the clinical and emotional state of a person; (b) the fact that no research on the voice in this syndrome has been conducted previously. The vocal timbre of most people diagnosed with SMS does not seem to be according to the complexion of diagnosed individuals, nor to their gender and age, so it could be interesting to attend the analysis of phonation of people with a rare genetic syndrome such as SMS. We used BioMetPhon, a specific piece of software to analyze the glottal source and biomechanics of vocals folds. Nineteen features related to dysphonia, physiology, and biomechanics of the vocal folds were considered. The adult phonation of 9 individuals with SMS was analyzed and compared to 100 normative male and female adult voices. Results showed that the phonation of the SMS group significantly deviates from the adult normophonic profile in more than one of the 19 features examined, such as stiffness of the thyroarytenoid muscle and dynamic mass of the vocal fold cover, among others.

Dosage-sensitive genes in autism spectrum disorders: From neurobiology to therapy

Autism spectrum disorders (ASDs) are a group of heterogenous neurodevelopmental disorders affecting 1 in 59 children. Syndromic ASDs are commonly associated with chromosomal rearrangements or dosage imbalance involving a single gene. Many of these genes are dosage-sensitive and regulate transcription, protein homeostasis, and synaptic function in the brain. Despite vastly different molecular perturbations, syndromic ASDs share core symptoms including social dysfunction and repetitive behavior. However, each ASD subtype has a unique pathogenic mechanism and combination of comorbidities that require individual attention. We have learned a great deal about how these dosage-sensitive genes control brain development and behaviors from genetically-engineered mice. Here we describe the clinical features of eight monogenic neurodevelopmental disorders caused by dosage imbalance of four genes, as well as recent advances in using genetic mouse models to understand their pathogenic mechanisms and develop intervention strategies. We propose that applying newly developed quantitative molecular and neuroscience technologies will advance our understanding of the unique neurobiology of each disorder and enable the development of personalized therapy.

Smith-Magenis Syndrome: Clues in the Clinic

As a multisystemic congenital mental retardation disorder/anomaly, Smith-Magenis syndrome (SMS) is commonly aroused from de novo interstitial deletion of the 17p11.2 chromosome. The deletion of this chromosome results with haploinsufficiency for the retinoic acid-induced 1 ( RAI1 ) gene. In this article, we present three cases, who were diagnosed with SMS with mental retardation and behavioral problems such as self-hugging and sleeping disturbances. During the evaluation of the patients, it has been found that there was a 3.4-Mb deletion in the 17p11.2 chromosome region of these patients. This deletion includes RAI1 that is a critically involved gene in SMS.

Management of Sleep Disturbances Associated with Smith-Magenis Syndrome

Smith-Magenis syndrome is a genetic disorder caused by a microdeletion involving the retinoic acid-induced 1 (RAI1) gene that maps on the short arm of chromosome 17p11.2 or a pathogenic mutation of RAI1. Smith-Magenis syndrome affects patients through numerous congenital anomalies, intellectual disabilities, behavioral challenges, and sleep disturbances. The sleep abnormalities associated with Smith-Magenis syndrome can include frequent nocturnal arousals, early morning awakenings, and sleep attacks during the day. The sleep problems associated with Smith-Magenis syndrome are attributed to haploinsufficiency of the RAI1 gene. One consequence of reduced function of RAI1, and characteristic of Smith-Magenis syndrome, is an inversion of melatonin secretion resulting in a diurnal rather than nocturnal pattern. Treatment of sleep problems in people with Smith-Magenis syndrome generally involves a combination of sleep hygiene techniques, supplemental melatonin, and/or other medications, such as melatonin receptor agonists, β₁-adrenergic antagonists, and stimulant medications, to improve sleep outcomes. Improvement in sleep has been shown to improve behavioral outcomes, which in turn improves the quality of life for both patients and their caregivers.

Twenty-four-hour motor activity and body temperature patterns suggest altered central circadian timekeeping in Smith-Magenis syndrome, a neurodevelopmental disorder

Smith-Magenis syndrome (SMS) is a contiguous gene syndrome linked to interstitial microdeletion, or mutation of RAI1, within chromosome 17p11.2. Key behavioral features of SMS include intellectual disability, sleep-disturbances, maladaptive, aggressive and self-injurious behaviors, hyperactivity, and sudden changes in mood. A distinguishing feature of this syndrome is an inverted pattern of melatonin characterized by elevated daytime and low nighttime melatonin levels. As the central circadian clock controls the 24-hr rhythm of melatonin, we hypothesized that the clock itself may contribute to the disrupted pattern of melatonin and sleep. In this report, 24-hr patterns of body temperature, a surrogate marker of clock-timing, and continuous wrist activity were collected to examine the links between body temperature, sleep behavior, and the circadian clock. In addition, age-dependent changes in sleep behavior were explored. Actigraphy-estimated sleep time for SMS was 1 hr less than expected across all ages studied. The timing of the 24-hr body temperature (Tb-24) rhythm was phase advanced, but not inverted. Compared to sibling (SIB) controls, the SMS group had less total night sleep, lower sleep efficiency, earlier sleep onset, earlier final awake times, increased waking after sleep onset (WASO), and increased daytime nap duration. The timing of wake onset varied with age, providing evidence of ongoing developmental sleep changes from childhood through adolescence. Clarification of the circadian and developmental factors that contribute to the disrupted and variable sleep patterns in this syndrome will be helpful in identifying more effective individualized treatments.

Mutations in ANKLE2, a ZIKA Virus Target, Disrupt an Asymmetric Cell Division Pathway in Drosophila Neuroblasts to Cause Microcephaly

The apical Par complex, which contains atypical protein kinase C (aPKC), Bazooka (Par-3), and Par-6, is required for establishing polarity during asymmetric division of neuroblasts in Drosophila, and its activity depends on L(2)gl. We show that loss of Ankle2, a protein associated with microcephaly in humans and known to interact with Zika protein NS4A, reduces brain volume in flies and impacts the function of the Par complex. Reducing Ankle2 levels disrupts endoplasmic reticulum (ER) and nuclear envelope morphology, releasing the kinase Ballchen-VRK1 into the cytosol. These defects are associated with reduced phosphorylation of aPKC, disruption of Par-complex localization, and spindle alignment defects. Importantly, removal of one copy of ballchen or l(2)gl suppresses Ankle2 mutant phenotypes and restores viability and brain size. Human mutational studies implicate the above-mentioned genes in microcephaly and motor neuron disease. We suggest that NS4A, ANKLE2, VRK1, and LLGL1 define a pathway impinging on asymmetric determinants of neural stem cell division.

Apical-Basal Polarity Signaling Components, Lgl1 and aPKCs, Control Glutamatergic Synapse Number and Function

Normal synapse formation is fundamental to brain function. We show here that an apical-basal polarity (A-BP) protein, Lgl1, is present in the postsynaptic density and negatively regulates glutamatergic synapse numbers by antagonizing the atypical protein kinase Cs (aPKCs). A planar cell polarity protein, Vangl2, which inhibits synapse formation, was decreased in synaptosome fractions of cultured cortical neurons from Lgl1 knockout embryos. Conditional knockout of Lgl1 in pyramidal neurons led to reduction of AMPA/NMDA ratio and impaired plasticity. Lgl1 is frequently deleted in Smith-Magenis syndrome (SMS). Lgl1 conditional knockout led to increased locomotion, impaired novel object recognition and social interaction. Lgl1+/- animals also showed increased synapse numbers, defects in open field and social interaction, as well as stereotyped repetitive behavior. Social interaction in Lgl1+/- could be rescued by NMDA antagonists. Our findings reveal a role of apical-basal polarity proteins in glutamatergic synapse development and function and also suggest a potential treatment for SMS patients with Lgl1 deletion.

Sleep in children with Smith–Magenis syndrome: a case–control actigraphy study

Study Objectives

The objectives of the study were (1) to compare both actigraphy and questionnaire-assessed sleep quality and timing in children with Smith–Magenis syndrome (SMS) to a chronologically age-matched typically developing (TD) group and (2) to explore associations between age, nocturnal and diurnal sleep quality, and daytime behavior.

Methods

Seven nights of actigraphy data were collected from 20 children with SMS (mean age 8.70; SD 2.70) and 20 TD children. Daily parent/teacher ratings of behavior and sleepiness were obtained. Mixed linear modeling was used to explore associations between total sleep time and daytime naps and behavior.

Results

Sleep in children with SMS was characterized by shorter total sleep time (TST), extended night waking, shorter sleep onset, more daytime naps, and earlier morning waking compared to the TD group. Considerable inter-daily and inter-individual variability in sleep quality was found in the SMS group, so caution in generalizing results is required. An expected inverse association between age and TST was found in the TD group, but no significant association was found for the SMS group. No between-group differences in sleep hygiene practices were identified. A bidirectional negative association between TST and nap duration was found for the SMS group. In the SMS group, increased afternoon sleepiness was associated with increased irritability (p = .007) and overactivity (p = .005).

Conclusion

These findings evidence poor sleep quality in SMS and the need to implement evidence-based interventions in this population.

Smith-Magenis Syndrome: Molecular Basis of a Genetic-Driven Melatonin Circadian Secretion Disorder

Smith-Magenis syndrome (SMS), linked to Retinoic Acid Induced (RAI1) haploinsufficiency, is a unique model of the inversion of circadian melatonin secretion. In this regard, this model is a formidable approach to better understand circadian melatonin secretion cycle disorders and the role of the RAI1 gene in this cycle. Sleep-wake cycle disorders in SMS include sleep maintenance disorders with a phase advance and intense sleepiness around noon. These disorders have been linked to a general disturbance of sleep-wake rhythm and coexist with inverted secretion of melatonin. The exact mechanism underlying the inversion of circadian melatonin secretion in SMS has rarely been discussed. We suggest three hypotheses that could account for the inversion of circadian melatonin secretion and discuss them. First, inversion of the circadian melatonin secretion rhythm could be linked to alterations in light signal transduction. Second, this inversion could imply global misalignment of the circadian system. Third, the inversion is not linked to a global circadian clock shift but rather to a specific impairment in the melatonin secretion pathway between the suprachiasmatic nuclei (SCN) and pinealocytes. The development of diurnal SMS animal models that produce melatonin appears to be an indispensable step to further understand the molecular basis of the circadian melatonin secretion rhythm.

What's retinoic acid got to do with it? Retinoic acid regulation of the neural crest in craniofacial and ocular development

Retinoic acid (RA), the active derivative of vitamin A (retinol), is an essential morphogen signaling molecule and major regulator of embryonic development. The dysregulation of RA levels during embryogenesis has been associated with numerous congenital anomalies, including craniofacial, auditory, and ocular defects. These anomalies result from disruptions in the cranial neural crest, a vertebrate-specific transient population of stem cells that contribute to the formation of diverse cell lineages and embryonic structures during development. In this review, we summarize our current knowledge of the RA-mediated regulation of cranial neural crest induction at the edge of the neural tube and the migration of these cells into the craniofacial region. Further, we discuss the role of RA in the regulation of cranial neural crest cells found within the frontonasal process, periocular mesenchyme, and pharyngeal arches, which eventually form the bones and connective tissues of the head and neck and contribute to structures in the anterior segment of the eye. We then review our understanding of the mechanisms underlying congenital craniofacial and ocular diseases caused by either the genetic or toxic disruption of RA signaling. Finally, we discuss the role of RA in maintaining neural crest-derived structures in postembryonic tissues and the implications of these studies in creating new treatments for degenerative craniofacial and ocular diseases.

A distinctive DNA methylation pattern in insufficient sleep

Short sleep duration or insomnia may lead to an increased risk of various psychiatric and cardio-metabolic conditions. Since DNA methylation plays a critical role in the regulation of gene expression, studies of differentially methylated positions (DMPs) might be valuable for understanding the mechanisms underlying insomnia. We performed a cross-sectional genome-wide analysis of DNA methylation in relation to self-reported insufficient sleep in individuals from a community-based sample (79 men, aged 39.3 ± 7.3), and in relation to shift work disorder in an occupational cohort (26 men, aged 44.9 ± 9.0). The analysis of DNA methylation data revealed that genes corresponding to selected DMPs form a distinctive pathway: "Nervous System Development" (FDR P value < 0.05). We found that 78% of the DMPs were hypomethylated in cases in both cohorts, suggesting that insufficient sleep may be associated with loss of DNA methylation. A karyoplot revealed clusters of DMPs at various chromosomal regions, including 12 DMPs on chromosome 17, previously associated with Smith-Magenis syndrome, a rare condition comprising disturbed sleep and inverse circadian rhythm. Our findings give novel insights into the DNA methylation patterns associated with sleep loss, possibly modifying processes related to neuroplasticity and neurodegeneration. Future prospective studies are needed to confirm the observed associations.

Rhythms of life: circadian disruption and brain disorders across the lifespan

Many processes in the human body - including brain function - are regulated over the 24-hour cycle, and there are strong associations between disrupted circadian rhythms (for example, sleep-wake cycles) and disorders of the CNS. Brain disorders such as autism, depression and Parkinson disease typically develop at certain stages of life, and circadian rhythms are important during each stage of life for the regulation of processes that may influence the development of these disorders. Here, we describe circadian disruptions observed in various brain disorders throughout the human lifespan and highlight emerging evidence suggesting these disruptions affect the brain. Currently, much of the evidence linking brain disorders and circadian dysfunction is correlational, and so whether and what kind of causal relationships might exist are unclear. We therefore identify remaining questions that may direct future research towards a better understanding of the links between circadian disruption and CNS disorders.

The behavioural phenotype of Potocki-Lupski syndrome: a cross-syndrome comparison

Background

Potocki-Lupski syndrome (PTLS) and Smith-Magenis syndrome (SMS) are related genomic disorders, as duplication 17p11.2 (associated with PTLS) is the reciprocal recombination product of the SMS microdeletion. While SMS has a relatively well-delineated behavioural phenotype, the behavioural profile in PTLS is less well defined, despite purported associations with autism spectrum disorder (ASD) and the suggestion that some behaviours may be diametric to those seen in SMS.

Methods

Caregivers of individuals with PTLS (N = 34; M age = 12.43, SD = 6.78) completed online behavioural questionnaires, including the Challenging Behaviour Questionnaire (CBQ), the Activity Questionnaire (TAQ), the Repetitive Behaviour Questionnaire (RBQ), the Mood, Interest and Pleasure Questionnaire-Short Form (MIPQ-S) and the Social Communication Questionnaire (SCQ), which assesses behaviours associated with ASD. Individuals with PTLS were matched on age and adaptive functioning to individuals with SMS (N = 31; M age = 13.61, SD = 6.85) and individuals with idiopathic ASD (N = 33; M age = 12.04, SD = 5.85) from an existing dataset.

Results

Individuals with PTLS and SMS were less impaired than those with idiopathic ASD on the communication and reciprocal social interaction subscales of the SCQ, but neither syndrome group differed from idiopathic ASD on the restricted, repetitive and stereotyped behaviours subscale. On the repetitive behaviour measure, individuals with PTLS and idiopathic ASD scored higher than individuals with SMS on the compulsive behaviour subscale. Rates of self-injury and property destruction were significantly lower in PTLS and idiopathic ASD than in SMS. No between-syndrome differences were found in relation to overactivity or mood; however, impulsivity was greater in SMS than in PTLS.

Conclusions

Findings suggest some overlap in the behavioural phenotype of PTLS and features of ASD symptomatology; however, the overall profile of behaviours in PTLS appears to be divergent from both idiopathic ASD and SMS. Relative to idiopathic ASD, PTLS is not characterised by communication or social interaction deficits. However, restricted and repetitive behaviours were evident in PTLS, and these may be characterised specifically by compulsive behaviours. While several behavioural differences were identified between PTLS and SMS, there was little evidence of diametric behavioural phenotypes, particularly in relation to social behaviour.

RAI1 gene mutations: mechanisms of Smith-Magenis syndrome

Smith-Magenis syndrome (SMS; OMIM #182290) is a complex genetic disorder characterized by distinctive physical features, developmental delay, cognitive impairment, and a typical behavioral phenotype. SMS is caused by interstitial 17p11.2 deletions, encompassing multiple genes and including the retinoic acid-induced 1 gene (RAI1), or by mutations in RAI1 itself. About 10% of all the SMS patients, in fact, carry an RAI1 mutation responsible for the phenotype. RAI1 (OMIM *607642) is a dosage-sensitive gene expressed in many tissues and highly conserved among species. Over the years, several studies have demonstrated that RAI1 (or its homologs in animal models) acts as a transcriptional factor implicated in embryonic neurodevelopment, neuronal differentiation, cell growth and cell cycle regulation, bone and skeletal development, lipid and glucose metabolisms, behavioral functions, and circadian activity. Patients with RAI1 pathogenic variants show some phenotypic differences when compared to those carrying the typical deletion. They usually have lower incidence of hypotonia and less cognitive impairment than those with 17p11.2 deletions but more frequently show the behavioral characteristics of the syndrome and overeating issues. These differences reflect the primary pathogenetic role of RAI1 without the pathogenetic contribution of the other genes included in the typical 17p11.2 deletion. The better comprehension of physiological roles of RAI1, its molecular co-workers and interactors, and its contribution in determining the typical SMS phenotype will certainly open a new path for therapeutic interventions.

Smith-Magenis Syndrome Patients Often Display Antibody Deficiency but Not Other Immune Pathologies

BACKGROUND

Smith-Magenis syndrome (SMS) is a complex neurobehavioral disorder associated with recurrent otitis. Most SMS cases result from heterozygous interstitial chromosome 17p11.2 deletions that encompass not only the intellectual disability gene retinoic acid-induced 1 but also other genes associated with immunodeficiency, autoimmunity, and/or malignancy.

OBJECTIVES

The goals of this study were to describe the immunological consequence of 17p11.2 deletions by determining the prevalence of immunological diseases in subjects with SMS and by assessing their immune systems via laboratory methods.

METHODS

We assessed clinical histories of 76 subjects with SMS with heterozygous 17p11.2 deletions and performed in-depth immunological testing on 25 representative cohort members. Laboratory testing included determination of serum antibody concentrations, vaccine titers, and lymphocyte subset frequencies. Detailed reactivity profiles of SMS serum antibodies were performed using custom-made antigen microarrays.

RESULTS

Of 76 subjects with SMS, 74 reported recurrent infections including otitis (88%), pneumonia (47%), sinusitis (42%), and gastroenteritis (34%). Infections were associated with worsening SMS-related neurobehavioral symptoms. The prevalence of autoimmune and atopic diseases was not increased. Malignancy was not reported. Laboratory evaluation revealed most subjects with SMS to be deficient of isotype-switched memory B cells and many to lack protective antipneumococcal antibodies. SMS antibodies were not more reactive than control antibodies to self-antigens.

CONCLUSIONS

Patients with SMS with heterozygous 17p.11.2 deletions display an increased susceptibility to sinopulmonary infections, but not to autoimmune, allergic, or malignant diseases. SMS sera display an antibody reactivity profile favoring neither recognition of pathogen-associated antigens nor self-antigens. Prophylactic strategies to prevent infections may also provide neurobehavioral benefits to selected patients with SMS.

Auditory Phenotype of Smith-Magenis Syndrome

Purpose

The purpose of this study was to describe the auditory phenotype of a large cohort with Smith-Magenis syndrome (SMS), a rare disorder including physical anomalies, cognitive deficits, sleep disturbances, and a distinct behavioral phenotype.

Method

Hearing-related data were collected for 133 individuals with SMS aged 1-49 years. Audiogram data (97 participants) were used for cross-sectional and longitudinal analyses. Caregivers completed a sound sensitivity survey for 98 individuals with SMS and a control group of 24 unaffected siblings.

Results

Nearly 80% of participants with interpretable audiograms (n = 76) had hearing loss, which was typically slight to mild in degree. When hearing loss type could be determined (40 participants), sensorineural hearing loss (48.1%) occurred most often in participants aged 11-49 years. Conductive hearing loss (35.2%) was typically observed in children aged 1-10 years. A pattern of fluctuating and progressive hearing decline was documented. Hyperacusis was reported in 73.5% of participants with SMS compared with 12.5% of unaffected siblings.

Conclusions

This study offers the most comprehensive characterization of the auditory phenotype of SMS to date. The auditory profile in SMS is multifaceted and can include a previously unreported manifestation of hyperacusis. Routine audiologic surveillance is recommended as part of standard clinical care.

Differences in Social Motivation in Children with Smith-Magenis Syndrome and Down Syndrome

Social excesses, characterised by heightened social motivation, are important for describing social functioning. Smith-Magenis syndrome (SMS) is a potential exemplar of a disorder where heightened social motivation is associated with negative behavioural outcomes. In Down syndrome (DS) strong social motivation is described, but less commonly associated with behavioural problems. Children with SMS (n = 21) and DS (n = 19) were observed during social situations, in which familiarity of adults present and level of attention available were manipulated. Motivation in SMS was characterised by comparatively frequent social initiations when adult attention was low, and stronger preference for familiar adults, compared to DS. Findings provide insight into the nature of social motivation in SMS and support an argument for nuanced consideration of motivation.

Recurrent De Novo and Biallelic Variation of ATAD3A, Encoding a Mitochondrial Membrane Protein, Results in Distinct Neurological Syndromes

ATPase family AAA-domain containing protein 3A (ATAD3A) is a nuclear-encoded mitochondrial membrane protein implicated in mitochondrial dynamics, nucleoid organization, protein translation, cell growth, and cholesterol metabolism. We identified a recurrent de novo ATAD3A c.1582C>T (p.Arg528Trp) variant by whole-exome sequencing (WES) in five unrelated individuals with a core phenotype of global developmental delay, hypotonia, optic atrophy, axonal neuropathy, and hypertrophic cardiomyopathy. We also describe two families with biallelic variants in ATAD3A, including a homozygous variant in two siblings, and biallelic ATAD3A deletions mediated by nonallelic homologous recombination (NAHR) between ATAD3A and gene family members ATAD3B and ATAD3C. Tissue-specific overexpression of bor^R534W, the Drosophila mutation homologous to the human c.1582C>T (p.Arg528Trp) variant, resulted in a dramatic decrease in mitochondrial content, aberrant mitochondrial morphology, and increased autophagy. Homozygous null bor larvae showed a significant decrease of mitochondria, while overexpression of bor^WT resulted in larger, elongated mitochondria. Finally, fibroblasts of an affected individual exhibited increased mitophagy. We conclude that the p.Arg528Trp variant functions through a dominant-negative mechanism that results in small mitochondria that trigger mitophagy, resulting in a reduction in mitochondrial content. ATAD3A variation represents an additional link between mitochondrial dynamics and recognizable neurological syndromes, as seen with MFN2, OPA1, DNM1L, and STAT2 mutations.

First evidence of Smith-Magenis syndrome in mother and daughter due to a novel RAI mutation

Smith-Magenis syndrome (SMS) is a complex genetic disorder caused by interstitial 17p11.2 deletions encompassing multiple genes, including the retinoic acid induced 1 gene-RAI1-or mutations in RAI1 itself. The clinical spectrum includes developmental delay, cognitive impairment, and behavioral abnormalities, with distinctive physical features that become more evident with age. No patients have been reported to have had offspring. We here describe a girl with developmental delay, mainly compromising the speech area, and her mother with mild intellectual disabilities and minor dysmorphic features. Both had sleep disturbance and attention deficit disorder, but no other atypical behaviors have been reported. In both, CGH-array analysis detected a 15q13.3 interstitial duplication, encompassing CHRNA7. However, the same duplication has been observed in several, apparently healthy, maternal relatives. We, thus, performed a whole exome sequencing analysis, which detected a frameshift mutation in RAI1, de novo in the mother, and transmitted to her daughter. No other family members carried this mutation. This is the first report of an SMS patient having offspring. Our experience confirms the importance of searching for alternative causative genetic mechanisms in case of confounding/inconclusive findings such as a CGH-array result of uncertain significance. © 2016 Wiley Periodicals, Inc.

Molecular and Neural Functions of Rai1, the Causal Gene for Smith-Magenis Syndrome

Haploinsufficiency of Retinoic Acid Induced 1 (RAI1) causes Smith-Magenis syndrome (SMS), which is associated with diverse neurodevelopmental and behavioral symptoms as well as obesity. RAI1 encodes a nuclear protein but little is known about its molecular function or the cell types responsible for SMS symptoms. Using genetically engineered mice, we found that Rai1 preferentially occupies DNA regions near active promoters and promotes the expression of a group of genes involved in circuit assembly and neuronal communication. Behavioral analyses demonstrated that pan-neural loss of Rai1 causes deficits in motor function, learning, and food intake. These SMS-like phenotypes are produced by loss of Rai1 function in distinct neuronal types: Rai1 loss in inhibitory neurons or subcortical glutamatergic neurons causes learning deficits, while Rai1 loss in Sim1⁺ or SF1⁺ cells causes obesity. By integrating molecular and organismal analyses, our study suggests potential therapeutic avenues for a complex neurodevelopmental disorder.

Non-invasive ventilation for sleep-disordered breathing in Smith-Magenis syndrome

Smith-Magenis syndrome (SMS) is a rare genetic neurodevelopmental disorder characterised by behavioural disturbances, intellectual disability and early onset obesity. The physical features of this syndrome are well characterised; however, behavioural features, such as sleep disturbance, are less well understood and difficult to manage. Sleep issues in SMS are likely due to a combination of disturbed melatonin cycle, facial anatomy and obesity-related ventilatory problems. Sleep disorders can be very distressing to patients and their families, as exemplified by our patient's experience, and can worsen behavioural issues as well as general health. This case demonstrates the successful use of non-invasive ventilation in treating underlying obesity hypoventilation syndrome and obstructive sleep apnoea. As a consequence of addressing abnormalities in sleep patterns, some behavioural problems improved.

Nonrecurrent PMP22-RAI1 contiguous gene deletions arise from replication-based mechanisms and result in Smith-Magenis syndrome with evident peripheral neuropathy

Hereditary neuropathy with liability to pressure palsies (HNPP) and Smith-Magenis syndrome (SMS) are genomic disorders associated with deletion copy number variants involving chromosome 17p12 and 17p11.2, respectively. Nonallelic homologous recombination (NAHR)-mediated recurrent deletions are responsible for the majority of HNPP and SMS cases; the rearrangement products encompass the key dosage-sensitive genes PMP22 and RAI1, respectively, and result in haploinsufficiency for these genes. Less frequently, nonrecurrent genomic rearrangements occur at this locus. Contiguous gene duplications encompassing both PMP22 and RAI1, i.e., PMP22-RAI1 duplications, have been investigated, and replication-based mechanisms rather than NAHR have been proposed for these rearrangements. In the current study, we report molecular and clinical characterizations of six subjects with the reciprocal phenomenon of deletions spanning both genes, i.e., PMP22-RAI1 deletions. Molecular studies utilizing high-resolution array comparative genomic hybridization and breakpoint junction sequencing identified mutational signatures that were suggestive of replication-based mechanisms. Systematic clinical studies revealed features consistent with SMS, including features of intellectual disability, speech and gross motor delays, behavioral problems and ocular abnormalities. Five out of six subjects presented clinical signs and/or objective electrophysiologic studies of peripheral neuropathy. Clinical profiling may improve the clinical management of this unique group of subjects, as the peripheral neuropathy can be more severe or of earlier onset as compared to SMS patients having the common recurrent deletion. Moreover, the current study, in combination with the previous report of PMP22-RAI1 duplications, contributes to the understanding of rare complex phenotypes involving multiple dosage-sensitive genes from a genetic mechanistic standpoint.