Interstitial Deletion Of Chromosome 17p11 Research Articles

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.

1161 Tasimelteon Shows Persistence Of Efficacy In Improving Sleep Disturbances In Patients With Smith-Magenis Syndrome (SMS) In Open-Label Extension Study

Abstract Introduction Smith-Magenis Syndrome (SMS) is a rare (1/15,000 - 25,000 births) neurodevelopmental disorder resulting from an interstitial deletion of chromosome 17p11.2, or from a point mutation in the RAI1 gene. Severe sleep disorder is almost universal in patients with SMS and poses a significant challenge to patients and their families. Tasimelteon improved sleep symptoms in a randomized, double-blind, two-period, crossover study; and here we show that this effect persists for up to four years in an open-label extension. To our knowledge, this is the largest interventional study of SMS patients to date. Methods Following the 4-week crossover study, all eligible participants had the option to enroll in an open-label extension. 31/39 (79.4%) of all individuals who participated in the efficacy study have continued on tasimelteon treatment. Participants in the open-label extension provided daily diary sleep quality (DDSQ), and daily diary total sleep time (DDTST) measures via parental post sleep questionnaire and characterized behavior using the Aberrant Behavior Checklist (ABC). Results In the open-label extension, tasimelteon continued to show improvement in the primary endpoints of 50% worst sleep quality (mean = 0.7, SD = 0.94) and 50% worst total nighttime sleep duration (mean = 53.3, SD = 59.01) when compared to baseline. Tasimelteon also improved overall sleep quality (mean=0.7, SD=0.83) and overall total nighttime sleep duration (mean = 51.9, SD=53.03). ABC scores also improved with tasimelteon (mean= -16.3, SD = 15.82). Conclusion Tasimelteon continues to demonstrate persistence in efficacy (longest approximately 4 years) with similar magnitudes observed in the 4-week crossover study for sleep quality and total sleep time. Interestingly, daytime behavior also demonstrates long-term improvement in patients with SMS treated with tasimelteon. These results further confirm tasimelteon as a novel therapy for the treatment of sleep disorders in patients with SMS and may provide benefit for behavioral symptoms. Support This work was supported by Vanda Pharmaceuticals Inc.

Reversed gender ratio of autism spectrum disorder in Smith-Magenis syndrome

BackgroundA substantial amount of research shows a higher rate of autistic type of problems in males compared to females. The 4:1 male to female ratio is one of the most consistent findings in autism spectrum disorder (ASD).Lately, the interest in studying ASD in genetic disorders has increased, and research has shown a higher prevalence of ASD in some genetic disorders than in the general population.Smith-Magenis syndrome (SMS) is a rare and complex genetic syndrome caused by an interstitial deletion of chromosome 17p11.2 or a mutation on the retinoic acid induced 1 gene. The disorder is characterised by intellectual disability, multiple congenital anomalies, obesity, neurobehavioural abnormalities and a disrupted circadian sleep-wake pattern.MethodsParents of 28 persons with SMS between 5 and 50 years old participated in this study. A total of 12 of the persons with SMS were above the age of 18 at the time of the study. A total of 11 came from Sweden and 17 were from Norway.We collected information regarding the number of autism spectrum symptoms using the Social Communication Questionnaire (SCQ) and the Social Responsiveness Scale (SRS). Adaptive behaviour was also measured using the Vineland Adaptive Behavior Scale II. The level of intellectual disability was derived from a review of the medical chart.ResultsWe found significant gender differences in ASD symptomatology using the SCQ and SRS questionnaires. We found approximately three females per male above the SCQ cutoff. The same differences were not found in the intellectual level and adaptive behaviour or for behavioural and emotional problems.Gender had an independent contribution in a regression model predicting the total SCQ score, and neither the Vineland Adaptive Behavior Scale II nor the Developmental Behaviour Checklist had an independent contribution to the SCQ scores.ConclusionWe found a clear reversed gender difference in ASD symptomatology in persons with SMS. This may be relevant in the search for female protective factors assumed to explain the male bias in ASD.

Dietary regimens modify early onset of obesity in mice haploinsufficient for Rai1.

Smith-Magenis syndrome is a complex genomic disorder in which a majority of individuals are obese by adolescence. While an interstitial deletion of chromosome 17p11.2 is the leading cause, mutation or deletion of the RAI1 gene alone results in most features of the disorder. Previous studies have shown that heterozygous knockout of Rai1 results in an obese phenotype in mice and that Smith-Magenis syndrome mouse models have a significantly reduced fecundity and an altered transmission pattern of the mutant Rai1 allele, complicating large, extended studies in these models. In this study, we show that breeding C57Bl/6J Rai1+/− mice with FVB/NJ to create F1 Rai1+/− offspring in a mixed genetic background ameliorates both fecundity and Rai1 allele transmission phenotypes. These findings suggest that the mixed background provides a more robust platform for breeding and larger phenotypic studies. We also characterized the effect of dietary intake on Rai1+/− mouse growth during adolescent and early adulthood developmental stages. Animals fed a high carbohydrate or a high fat diet gained weight at a significantly faster rate than their wild type littermates. Both high fat and high carbohydrate fed Rai1+/− mice also had an increase in body fat and altered fat distribution patterns. Interestingly, Rai1+/− mice fed different diets did not display altered fasting blood glucose levels. These results suggest that dietary regimens are extremely important for individuals with Smith- Magenis syndrome and that food high in fat and carbohydrates may exacerbate obesity outcomes.

Pharmacological treatment of disruptive behavior in Smith–Magenis syndrome

Smith-Magenis syndrome (SMS) is a complex genetic syndrome caused by an interstitial deletion of chromosome 17p11.2. Children and adults with SMS appear to have unique neurobehavioral problems that include: sleep disturbance, self-injurious and maladaptive behaviors, stereotypies, and sensory integration disorders. We gathered retrospective psychotropic use information from parents or other caregivers of 62 individuals with SMS who were asked about use of psychotropic medication from a list of commonly used psychiatric medications. For those drugs identified, respondents were asked to rate the experience with the particular medication using a likert-type scale. Drugs were grouped into seven main categories: (1) stimulants; (2) antidepressants; (3) antipsychotics; (4) sleep aides; (5) mood stabilizers; (6) alpha 2 agonists; and (7) benzodiazepines. Relative frequencies, means and standard deviations pertaining to age and medication effect were derived for each medication category. Six of the seven medication categories examined showed no meaningful deviations from the "no change" score. The benzodiazepine group showed a mild detrimental effect. There were no gender differences in efficacy. Use of psychotropic medication started early in life (mean age 5 years), particularly with sleep aides. Although no medication category was identified as efficacious in SMS, all the categories reported herein may be considered as an option for brief symptomatic relief.

Circadian rhythm disorder in a rare disease: Smith–Magenis syndrome

Smith–Magenis syndrome (SMS) is a clinically recognizable contiguous gene syndrome, caused by interstitial deletion of chromosome 17p11.2. The SMS phenotype include distinctive facial features, developmental delay and neurobehavioral abnormalities. The patients present major sleep disturbances ascribed to a phase shift of their circadian rhythm of melatonin with a paradoxical diurnal secretion of the hormone. Treatment with morning beta-blockers and evening melatonin reinstated a normally timed melatonin circadian rhythm, improved daytime behavior and restored normal sleep habits, resulting in a greatly improved quality of life for both SMS patients and their family. SMS is the demonstration of biological basis for sleep disorder in a genetic disease. Considering that clock genes mediate generation of circadian rhythms, we suggest that haploinsufficiency for a circadian system gene mapping to chromosome 17p11.2 may cause the inversion of circadian rhythm in SMS.

Detection and delineation of an unusual 17p11.2 deletion by array-CGH and refinement of the Smith–Magenis syndrome minimum deletion to ~650 kb

Smith–Magenis syndrome (SMS) is a multiple congenital anomaly/mental retardation syndrome and it is characterized by an interstitial deletion of chromosome 17p11.2. SMS patients have a distinct phenotype which is believed to be caused by haploinsufficiency of one or more genes in the associated deleted region. Five non-deletion patients with classical phenotypic features of SMS have been reported with mutations in the retinoic acid induced 1 ( RAI1) gene, located within the SMS critical interval. Happloinsufficiency of the RAI1 gene is likely to be the responsible gene for the majority of the SMS features, but other deleted genes in the SMS region may modify the overall phenotype in the patients with 17p11.2 deletions. SMS is usually diagnosed in the clinical genetic setting by FISH analysis using commercially available probes. We detected a submicroscopic deletion in 17p11.2 using array-CGH with a resolution of approximately 1 Mb in a patient with the SMS phenotype, who was not deleted for the commercially available SMS microdeletion FISH probe. Delineation of the deletion was performed using a 32K tiling BAC-array, containing 32,500 BAC clones. The deletion in this patient was size mapped to 2.7 Mb and covered the RAI1 gene. This case enabled the refinement of the SMS minimum deletion to ~650 kb containing eight putative genes and one predicted gene. In addition, it demonstrates the importance to investigate deletion of RAI1 in SMS patients.

Diagnostic FISH probes for del(17)(p11.2p11.2) associated with Smith–Magenis syndrome should contain the RAI1 gene

Smith-Magenis syndrome (SMS) is a mental retardation syndrome with distinctive behavioral characteristics, dysmorphic features, and congenital anomalies usually associated with an interstitial deletion of chromosome 17p11.2. While high quality G-banding will identify most SMS patients, fluorescent in situ hybridization (FISH) is the recommended test for confirmation of an SMS diagnosis. Recently, haploinsufficiency of the RAI1 gene due to deletion or mutation was determined to be the likely cause of SMS. All diagnostic FISH probes available commercially contain the FLII gene and are approximately 580 kb centromeric to RAI1. We present two patients with SMS who have interstitial deletions at 17p11.2 but are not deleted for currently available commercial FISH probes that include FLII; both patients have deletions that are demonstrated with probes containing the RAI1 gene. We recommend that for diagnostic accuracy, all future FISH tests for SMS be performed with probes containing the RAI1 gene, as some atypical deletions in the region critical to the SMS phenotype will otherwise be missed.

Systemic growth hormone corrects sleep disturbance in Smith–Magenis syndrome

Smith–Magenis syndrome (SMS) is a multiple congenital anomaly syndrome characterized by an interstitial deletion of chromosome 17p11.2. Sleep problems such as nocturnal awakening and abnormality in the percentage of rapid eye movement (REM) sleep are frequently observed in patients with SMS, and several medications have been administered to improve the sleep disorders. Here we present a female case of SMS showing early waking and reduction of REM sleep, which were corrected by human growth hormone (GH) replacement for her dwarfism. Also, we report changes in the sleep-wakefulness circadian rhythm and polysomnographical data before and after the start of human GH replacement. It is speculated that GH deficiency could be involved in sleep disturbance in SMS.

Anatomical and functional brain imaging evidence of lenticulo-insular anomalies in Smith Magenis syndrome

Smith Magenis syndrome (SMS) is a clinically recognizable contiguous gene syndrome ascribed to an interstitial deletion of chromosome 17p11.2. The neurobehavioral phenotype of SMS includes mental retardation, speech delay, hyperactivity, attention deficit, decreased sensitivity to pain, self-injury, aggressive behavior and sleep disturbance. Therefore, we performed anatomical and functional brain imaging studies in five SMS boys. Anatomical magnetic resonance imaging (MRI) was analyzed using optimized voxel-based morphometry (VBM). This method can detect structural anomalies not apparent on visual inspection of the scans. Two comparison groups with similar mean age were studied: Group A with 12 healthy control children and Group B with 5 children with idiopathic mental retardation. In addition, positron emission tomography (PET) and water-labeled method were used to investigate a putative localized brain dysfunction in SMS. The control group was composed of mentally retarded children (Group B). A significant bilateral decrease of grey matter concentration was detected in the insula and lenticular nucleus in SMS children. In addition, a significant hypoperfusion was found in the same regions in SMS. These anatomo-functional evidences of bilateral insulo-lenticular anomalies in SMS are consistent with neurobehavioral symptoms of the disease. The identification of localized brain anomalies in SMS may help in understanding how this well-defined genetic entity can lead to a relatively specific severe neurobehavioral syndrome.

Refinement of the Smith–Magenis syndrome critical region to ∼950 kb and assessment of 17p11.2 deletions. Are all deletions created equally?

Smith–Magenis syndrome (SMS) is a multiple congenital anomalies/mental retardation syndrome associated with an interstitial deletion of chromosome 17p11.2. SMS is thought to be a contiguous gene syndrome caused by haploinsufficiency of one or more genes in the associated deletion region. To date, no gene has been reported to contribute to the characteristics seen in the SMS phenotype. To expedite the search for the SMS causative genes, we have reduced the SMS critical region to ∼950 kb by analyzing 11 patient samples carrying 17p11.2 deletions. In addition, we have re-evaluated the frequency with which different 17p11.2 deletions naturally occur, showing evidence that homologous recombination likely takes place between low copy repeats at a higher frequency than previously reported.

Syndrome de Smith-Magenis

Background. — The main features of the Smith-Magenis syndrome include broad flat midface, brachycephaly, broad nasal bridge, brachydactyly, hoarse deep voice, speech and developmental delay, and behavioral anomalies. This syndrome is due to interstitial deletion of chromosome 17p11.2. Case report. — A 7-year-old girl was admitted for mental retardation. Clinical examination showed brachycephaly, broad flat midface, broad nasal bridge, malar hypoplasia, brachydactyly, decreased or absent deep tendon reflexes, and hoarse deep voice. She had a mild deafness, behavioral problems, and sleep disturbances. Chromosome analysis on lymphocytes identified a microdeletion of one chromosome subband 17p11.2. Molecular studies indicated loss of maternal allele. Conclusion. — The Smith-Magenis syndrome is probably underdiagnosed because of its usually mild clinical features. High-resolution chromosome analysis is needed for diagnosis.