Identification of Nine New RAI1-Truncating Mutations in Smith-Magenis Syndrome Patients without 17p11.2 Deletions

Discriminative features in White-Sutton syndrome: literature review and first report in Iran

White-Sutton Syndrome is one of the rare neurodevelopmental disorder inherited in an autosomal dominant manner, mainly caused by de novo mutations in the POGZ gene and shows many phenotypic signs such as intellectual disability, Autism Spectrum Disorder and other spectra. About 70 patients with this syndrome have been reported worldwide. In this paper, we have described different phenotypic features of the White-Sutton Syndrome with a brief review of recent literatures. Finally, we have reported an Iranian male with intellectual disability and visual impairment. We have explained the clinical symptoms of the patient and have compared the patient's phenotype with existing data from individuals with White-Sutton Syndrome. The results of Whole Exome Sequencing test, performed for the patient, declared the presence of a de novo mutation in POGZ gene and confirmed the White-Sutton Syndrome diagnosis.

A case of Smith-Magenis syndrome with skin manifestations caused by a novel locus mutation in the RAI1 gene

We report the clinical features and genetic testing of a child with Smith-Magenis syndrome (SMS) to improve the understanding of this disease. The clinical data and molecular genetic test results of a child with SMS caused by a novel mutation in the retinoic acid-induced-1 (RAI1) gene were reviewed. A female patient aged 12 years and 9 months presented to the clinic because her mental and motor development was lagging behind that of her peers. The child had learning difficulties, poor motor coordination, temper tantrums, and self-injurious behaviors, such as skin scratching. She had a peculiar facial appearance, dry skin with scattered eczema, low hairline, wide forehead, flat face, collapsed nasal bridge, turned out upper lip, and deep palmar lines on the right hand through the palm. Wechsler's IQ test score was 48. Her electroencephalogram was normal. The diagnosis of SMS was confirmed by a heterozygous mutation in exon 3 of the RAI1 gene on chromosome chr-1717696650 at locus c.388C>T (P.Q130X). In addition, this patient had severe eczema on the skin. The RAI1 mutation c.388C>T (P.Q130X) is a newly reported variant that will help in the clinical identification of SMS and the precise localization of more phenotypically related genes.

Two Monogenetic Disorders, Activated PI3-Kinase-δ Syndrome 2 and Smith-Magenis Syndrome, in One Patient: Case Report and a Literature Review of Neurodevelopmental Impact in Primary Immunodeficiencies Associated With Disturbed PI3K Signaling

Activated PI3-kinase-δ syndrome 2 (APDS2) is caused by autosomal dominant mutations in the PIK3R1 gene encoding the p85α, p55α, and p50α regulatory subunits. Most diagnosed APDS2 patients carry mutations affecting either the splice donor or splice acceptor sites of exon 11 of the PIK3R1 gene responsible for an alternative splice product and a shortened protein. The clinical presentation of APDS2 patients is highly variable, ranging from mild to profound combined immunodeficiency features as massive lymphoproliferation, increased susceptibility to bacterial and viral infections, bronchiectasis, autoimmune manifestations, and occurrence of cancer. Non-immunological features such as growth retardation and neurodevelopmental delay have been reported for APDS2 patients. Here, we describe a patient suffering from an APDS2 associated with a Smith-Magenis syndrome (SMS), a complex genetic disorder affecting, among others, neurological manifestations and review the literature describing neurodevelopmental impacts in APDS2 and other PIDs/monogenetic disorders associated with dysregulated PI3K signaling.

Sleep as a translationally-relevant endpoint in studies of autism spectrum disorder (ASD)

Sleep has numerous advantages for aligning clinical and preclinical (basic neuroscience) studies of neuropsychiatric illness. Sleep has high translational relevance, because the same endpoints can be studied in humans and laboratory animals. In addition, sleep experiments are conducive to continuous data collection over long periods (hours/days/weeks) and can be based on highly objective neurophysiological measures. Here, we provide a translationally-oriented review on what is currently known about sleep in the context of autism spectrum disorder (ASD), including ASD-related conditions, thought to have genetic, environmental, or mixed etiologies. In humans, ASD is frequently associated with comorbid medical conditions including sleep disorders. Animal models used in the study of ASD frequently recapitulate dysregulation of sleep and biological (diurnal, circadian) rhythms, suggesting common pathophysiologies across species. As our understanding of the neurobiology of ASD and sleep each become more refined, it is conceivable that sleep-derived metrics may offer more powerful biomarkers of altered neurophysiology in ASD than the behavioral tests currently used in humans or lab animals. As such, the study of sleep in animal models for ASD may enable fundamentally new insights on the condition and represent a basis for strategies that enable the development of more effective therapeutics.

Parental experiences with behavioural problems in Smith-Magenis syndrome: The need for syndrome-specific competence

The experience of having a rare disorder was summarised in a large study as 'falling outside the vast field of knowledge of the professionals'. Parents (31 mothers and 17 fathers) of 32 persons with Smith-Magenis syndrome (SMS) participated in this study. A phenomenological approach was used to analyse the data into topics and themes. Four themes emerged: behavioural challenges displayed, parents' strategies for meeting the challenging behaviours, parents' experiences of their own competence and parents' experiences of professionals' competence and understanding regarding children with SMS and their behaviour challenges. We found that parents of children with SMS experience that they are exposed to severe challenging behaviours from their child. The parents believe that they experience more misunderstandings with professionals and that the challenging behaviours increase because there are some specific characteristics of SMS that professionals are not aware of or do not consider in their support services.

A Rare De Novo RAI1 Gene Mutation Affecting BDNF-Enhancer-Driven Transcription Activity Associated with Autism and Atypical Smith-Magenis Syndrome Presentation

Deletions and mutations involving the Retinoic Acid Induced 1 (RAI1) gene at 17p11.2 cause Smith-Magenis syndrome (SMS). Here we report a patient with autism as the main clinical presentation, with some SMS-like features and a rare de novo RAI1 gene mutation, c.3440G > A (p.R1147Q). We functionally characterized the RAI1 p.R1147Q mutant protein. The mutation, located near the nuclear localization signal, had no effect on the subcellular localization of the mutant protein. However, similar to previously reported RAI1 missense mutations in SMS patients, the RAI1 p.R1147Q mutant protein showed a significant deficiency in activating in vivo transcription of a reporter gene driven by a BDNF (brain-derived neurotrophic factor) intronic enhancer. In addition, expression of other genes associated with neurobehavioral abnormalities and/or neurodevelopmental disorders were found to be altered in this patient. These results suggest a likely contribution of RAI1, either alone or in combination of other factors, to social behavior and reinforce the RAI1 gene as a candidate gene in patients with autistic manifestations or social behavioral abnormalities.

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.

A systematic review of genetic syndromes with obesity

Syndromic monogenic obesity typically follows Mendelian patterns of inheritance and involves the co-presentation of other characteristics, such as mental retardation, dysmorphic features and organ-specific abnormalities. Previous reviews on obesity have reported 20 to 30 syndromes but no systematic review has yet been conducted on syndromic obesity. We searched seven databases using terms such as 'obesity', 'syndrome' and 'gene' to conduct a systematic review of literature on syndromic obesity. Our literature search identified 13,719 references. After abstract and full-text review, 119 relevant papers were eligible, and 42 papers were identified through additional searches. Our analysis of these 161 papers found that 79 obesity syndromes have been reported in literature. Of the 79 syndromes, 19 have been fully genetically elucidated, 11 have been partially elucidated, 27 have been mapped to a chromosomal region and for the remaining 22, neither the gene(s) nor the chromosomal location(s) have yet been identified. Interestingly, 54.4% of the syndromes have not been assigned a name, whereas 13.9% have more than one name. We report on organizational inconsistencies (e.g. naming discrepancies and syndrome classification) and provide suggestions for improvements. Overall, this review illustrates the need for increased clinical and genetic research on syndromes with obesity.

Rai1 frees mice from the repression of active wake behaviors by light

Besides its role in vision, light impacts physiology and behavior through circadian and direct (aka ‘masking’) mechanisms. In Smith-Magenis syndrome (SMS), the dysregulation of both sleep-wake behavior and melatonin production strongly suggests impaired non-visual light perception. We discovered that mice haploinsufficient for the SMS causal gene, Retinoic acid induced-1 (Rai1), were hypersensitive to light such that light eliminated alert and active-wake behaviors, while leaving time-spent-awake unaffected. Moreover, variables pertaining to circadian rhythm entrainment were activated more strongly by light. At the input level, the activation of rod/cone and suprachiasmatic nuclei (SCN) by light was paradoxically greatly reduced, while the downstream activation of the ventral-subparaventricular zone (vSPVZ) was increased. The vSPVZ integrates retinal and SCN input and, when activated, suppresses locomotor activity, consistent with the behavioral hypersensitivity to light we observed. Our results implicate Rai1 as a novel and central player in processing non-visual light information, from input to behavioral output.

DOI:http://dx.doi.org/10.7554/eLife.23292.001

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.

Fine mapping of bone structure and strength QTLs in heterogeneous stock rat

We previously demonstrated that skeletal structure and strength phenotypes vary considerably in heterogeneous stock (HS) rats. These phenotypes were found to be strongly heritable, suggesting that the HS rat model represents a unique genetic resource for dissecting the complex genetic etiology underlying bone fragility. The purpose of this study was to identify and localize genes associated with bone structure and strength phenotypes using 1524 adult male and female HS rats between 17 to 20 weeks of age. Structure measures included femur length, neck width, head width; femur and lumbar spine (L3-5) areas obtained by DXA; and cross-sectional areas (CSA) at the midshaft, distal femur and femoral neck, and the 5th lumbar vertebra measured by CT. In addition, measures of strength of the whole femur and femoral neck were obtained. Approximately 70,000 polymorphic SNPs distributed throughout the rat genome were selected for genotyping, with a mean linkage disequilibrium coefficient between neighboring SNPs of 0.95. Haplotypes were estimated across the entire genome for each rat using a multipoint haplotype reconstruction method, which calculates the probability of descent at each locus from each of the 8 HS founder strains. The haplotypes were then tested for association with each structure and strength phenotype via a mixed model with covariate adjustment. We identified quantitative trait loci (QTLs) for structure phenotypes on chromosomes 3, 8, 10, 12, 17 and 20, and QTLs for strength phenotypes on chromosomes 5, 10 and 11 that met a conservative genome-wide empiric significance threshold (FDR=5%; P<3×10(-6)). Importantly, most QTLs were localized to very narrow genomic regions (as small as 0.3 Mb and up to 3 Mb), each harboring a small set of candidate genes, both novel and previously shown to have roles in skeletal development and homeostasis.

Whole exome sequencing identifies RAI1 mutation in a morbidly obese child diagnosed with ROHHAD syndrome

CONTEXT

The current obesity epidemic is attributed to complex interactions between genetic and environmental factors. However, a limited number of cases, especially those with early-onset severe obesity, are linked to single gene defects. Rapid-onset obesity with hypothalamic dysfunction, hypoventilation and autonomic dysregulation (ROHHAD) is one of the syndromes that presents with abrupt-onset extreme weight gain with an unknown genetic basis.

OBJECTIVE

To identify the underlying genetic etiology in a child with morbid early-onset obesity, hypoventilation, and autonomic and behavioral disturbances who was clinically diagnosed with ROHHAD syndrome. Design/Setting/Intervention: The index patient was evaluated at an academic medical center. Whole-exome sequencing was performed on the proband and his parents. Genetic variants were validated by Sanger sequencing.

RESULTS

We identified a novel de novo nonsense mutation, c.3265 C>T (p.R1089X), in the retinoic acid-induced 1 (RAI1) gene in the proband. Mutations in the RAI1 gene are known to cause Smith-Magenis syndrome (SMS). On further evaluation, his clinical features were not typical of either SMS or ROHHAD syndrome.

CONCLUSIONS

This study identifies a de novo RAI1 mutation in a child with morbid obesity and a clinical diagnosis of ROHHAD syndrome. Although extreme early-onset obesity, autonomic disturbances, and hypoventilation are present in ROHHAD, several of the clinical findings are consistent with SMS. This case highlights the challenges in the diagnosis of ROHHAD syndrome and its potential overlap with SMS. We also propose RAI1 as a candidate gene for children with morbid obesity.