スミス・マギニス症候群

Background: Smith-Magenis syndrome (SMS) is a rare neurodevelopmental disorder characterized by severe sleep disturbances, circadian rhythm dysregulation, and prominent behavioral difficulties. Objective: To examine associations between subjective and objective sleep and circadian characteristics and behavioral difficulties in children with SMS in real life. Methods: Children aged 5-13 years with genetically confirmed SMS were included in a prospective single-center cohort study. Sleep and circadian rhythms were assessed using parent-reported questionnaires (Sleep Disturbance Scale for Children (SDSC), Horne and Östberg Morningness-Eveningness Questionnaire (H&O)) and 15-day home-based wrist actigraphy. Behavioral difficulties were evaluated using the Aberrant Behavior Checklist-Community (ABC-C). Associations between subjective and objective sleep and circadian measures with behavioral difficulties were studied using Spearman correlations for each ABC-C subscale. Results: Among the 20 children included (55% female, mean age 10 ± 2.5 years), 75% were carriers of a 17p11.2 microdeletion and 25% had an RAI1 mutation. Overall, 95% of children were treated with melatonin, 55% with psychostimulants and 20% with beta-blockers. According to the SDSC results, pathological sleep disturbances were present in 14/20 (70%) children and concerned mainly complaints of insomnia (10/20, 50%) and excessive daytime sleepiness (8/20, 40%). The H&O chronotypes confirmed the morning type in 70% of patients. Sleep and circadian measures obtained by actigraphy showed reduced total sleep time in 71% of the children, reduced sleep efficiency in 88%, long wake after sleep onset (WASO > 60 min) in 59%, as well as an early L5 onset (5 h period with the least movements < 23:38) and M10 onset (10 h period with the highest activity levels < 09:12) in 92% and 62% of children, respectively. The behavioral domains of the ABC-C with the highest scores were hyperactivity (mean 52.1, range 2.1-97.9) and irritability, agitation, and crying (mean 46.9, range 17.8-82.2). In the analysis of the relationship between behavior and sleep, a positive correlation was found between sleep disorders and stereotyped behaviors (r = 0.472, p = 0.048), insomnia and irritability, social withdrawal and stereotyped behaviors (r = 0.472, p = 0.048; r = 0.701, p = 0.001; and r = 0.648, p = 0.004, respectively), and non-restorative sleep and inappropriate speech (r = 0.476, p = 0.046). No significant association was found between objective sleep measures and behaviors. While subjective assessments suggested that a stronger morning chronotype was associated with lower irritability (r = -0.565, p = 0.015), actigraphy-derived circadian rhythm analyses revealed that an earlier L5 onset was associated with greater social withdrawal and hyperactivity (r = -0.556, p = 0.048 and r = -0.560, p = 0.049, respectively). Conclusions: The present cohort study of children with SMS studied in real-life conditions, using both objective and subjective measures, shows that patients continued to experience sleep and behavioral disturbances despite treatment. Exploratory analyses identified distinct associations between subjective sleep disturbances, circadian rhythm characteristics, and specific behavioral domains. While subjective sleep disturbances were associated with irritability, stereotypic behavior, and inappropriate speech, circadian rhythm parameters are specifically associated with hyperactivity. Both were also associated with social withdrawal. As these findings arise from an exploratory observational secondary analysis, they should be considered hypothesis-generating and require confirmation in larger prospective studies. If confirmed, they may help identify sleep and circadian rhythm characteristics as potential targets for future interventions in children with SMS.

This case reviews the use of a Glucagon-Like Peptide-1 Receptor Agonist (GLP1RA) in a young man presenting with excessive hunger and rapid weight gain compounded by an underlying rare form of genetic obesity, Smith-Magenis syndrome. The patient had, prior to presentation, seen an accelerated and persistent weight gain over the last five years despite attempts at portion control and behavior modification. Due to concerns of worsening metabolic disease, including prediabetes, dyslipidemia, and fatty liver disease, we started the patient on daily liraglutide and gradually titrated to the maximum dose over five months. He was able to tolerate the medication without severe gastrointestinal side effects, and alongside lifestyle and behavioral modifications, the patient lost 22.2 kg (49 lbs) over the course of 11 months. To our knowledge, there is only one other published case report documenting the use of GLP1RA therapy in a patient with Smith-Magenis syndrome.

A variety of genomic rearrangement mechanisms contribute to copy number variations at the 17p11.2 locus driven in part by its complex genomic architecture which is characterized by low copy repeats (LCRs) and other repetitive elements. These copy number variants are primarily mediated by nonallelic homologous recombination (NAHR) leading to recurrent tandem duplications and reciprocal deletions of the genomic interval mapping between the repeats. Two notable neurodevelopmental genomic disorders: Potocki-Lupski Syndrome (PTLS; MIM: 610883) and Smith-Magenis Syndrome (SMS; MIM: 182290) are driven by LCRs that undergo NAHR between the directly oriented repeats causing a duplication (PTLS) or deletion (SMS) encompassing the dosage-sensitive gene RAI1. We observed that other uncommon gains of varying sizes and extent at the 17p11.2 locus, which do not include the RAI1 gene, could be found in patients ascertained with a neurodevelopmental delay (NDD) phenotype. We ascertained 15 individuals from 11 families with copy number gains at the 17p11.2 locus not encompassing the driver gene-RAI1; such individuals manifested a broad spectrum of neurodevelopmental phenotypes. To validate our genomic findings, investigate DNA rearrangement mechanism(s), and refine our understanding at the breakpoint junctions, we performed a combination of high-resolution array CGH (n = 15), short-read whole-genome sequencing (sr-GS, n = 4), long-read GS (lr-GS; ONT; n = 4 and PacBio HiFi; n = 4), and breakpoint junctional analysis on this subset. Phenotypes in each individual were systematically studied. The phenotypes noted in these 15 individuals from 11 families primarily included developmental delay, intellectual disability, and behavioral problems. The genomic variations found in these 11 families included simple copy number gains (n = 7), higher order amplifications (n = 2), and complex genomic rearrangements (n = 2) at the 17p11.2 locus, surrounding the RAI1 gene and not encompassing it. Individuals from 4/11 families carried inherited variants. Identification of such rearrangement gains at the 17p11.2 locus that do not include the driver gene RAI1 and yet research subjects still exhibit neurodevelopmental phenotypes creates an opportunity to (i) dissect the gene(s) and genetic mechanisms that might contribute to phenotypic variability at the PTLS locus and (ii) uncover previously unrecognized genes or disease pathways and mechanisms.

Smith-Magenis syndrome (SMS) is a rare multisystem genetic disorder caused by a 17p11.2 microdeletion or pathogenic variants in the retinoic acid-induced 1 (RAI1) gene. It is characterized by developmental delay, distinctive craniofacial features, behavioral dysregulation, and inverted sleep-wake rhythm. Because early clinical findings are often nonspecific, diagnosis is frequently delayed, and patients may initially present to child psychiatry services with behavioral complaints. We report a 5-year-old girl referred for hyperactivity, severe circadian sleep disturbance with recurrent nocturnal awakenings, self-injurious behaviors, sensory-seeking behaviors, and developmental delay. Comprehensive psychiatric, developmental, neurological, physical, and genetic evaluations revealed a 17p11.2 microdeletion involving both RAI1 and folliculin (FLCN). The diagnosis of SMS was confirmed, and the involvement of FLCN indicated additional potential long-term medical risks. This case underscores the importance of considering genetic etiologies in children presenting with severe behavioral dysregulation and sleep problems and highlights the critical role of comprehensive genetic assessment in guiding diagnosis, management, and long-term follow-up.

Human brain development proceeds on an unusually long timeline relative to other species, a feature that is thought to foster advanced cognitive abilities. The Retinoic Acid Induced 1 (RAI1) gene encodes a nucleosome-binding protein, and its haploinsufficiency is responsible for Smith-Magenis Syndrome (SMS), a neurodevelopmental disorder characterized by cognitive impairment with autistic features. However, the role of RAI1 in human neurodevelopment remains unexplored experimentally. Here, we generated isogenic heterozygous and homozygous RAI1 loss-of-function human embryonic stem cell lines and interrogated the roles of RAI1 in neurodevelopmental gene regulation. A longitudinal transcriptome analysis during in vitro cortical development revealed that RAI1 deficiency accelerates the progression of developmental gene expression. Single-cell RNA-seq analysis revealed that RAI1-deficient neuroprogenitors acquire a transient mesoderm-like gene expression signature, followed by a pro-neuronal maturation signature in postmitotic neurons. Unexpectedly, the developmental acceleration signature was exacerbated during NGN2-induced excitatory neuron differentiation, isolating the roles of RAI1 in neuronal differentiation from non-neuronal functions. Together, these results identify RAI1 as a suppressor of the mesodermal lineage program and as a brake that slows the tempo of human neurodevelopmental gene expression.