Behavioral phenotype of Smith-Magenis syndrome (del 17p11.2)

A case report of monozygotic twins with Smith-Magenis syndrome

Monozygotic 3.5-year-old twin boys presented for developmental assessment with a history of global developmental delay, behavioral issues including self-harm, and severe receptive and expressive language delays. Chromosome testing confirmed for both a 17p11.2 interstitial microdeletion commonly seen in Smith-Magenis syndrome (SMS), which is characterized by developmental delay, cognitive impairment, and facial and behavioral phenotype. To our knowledge, this is the first description in the literature of monozygotic twins with SMS. Despite their zygosity, the twins had marked differences in presentation including cardiac and renal anomalies, language development, and behavioral phenotype. Both twins displayed disordered speech development, impairments in social interaction, and stereotyped behaviors consistent with autism spectrum disorder, common in the vast majority of cases of SMS. Examining the differences in behavioral and clinical phenotype in monozygotic twins may lead to a better understanding of the cause of the clinical variability seen in SMS, as well as the natural history of this syndrome.

Smith-Magenis syndrome

Smith-Magenis syndrome (SMS) is a complex neurobehavioral disorder caused by haploinsufficiency of the retinoic acid-induced 1 (RAI1) gene on chromosome 17p11.2. Diagnostic strategies include molecular identification of a 17p11.2 microdeletion encompassing RAI1 or a mutation in RAI1. G-banding and fluorescent in situ hybridization (FISH) are the classical methods used to detect the SMS deletions, while multiplex ligation-dependent probe amplification (MLPA) and real-time quantitative PCR are the newer, cost-effective, and high-throughput technologies. Most SMS features are due to RAI1 haploinsufficiency, while the variability and severity of the disorder are modified by other genes in the 17p11.2 region. The functional role for RAI1 is not completely understood, but it is likely involved in transcription, based on homology and preliminary studies. Management of SMS is primarily a multidisciplinary approach and involves treatment for sleep disturbance, speech and occupational therapies, minor medical interventions, and management of behaviors.

Abnormal melatonin synthesis in autism spectrum disorders

Melatonin is produced in the dark by the pineal gland and is a key regulator of circadian and seasonal rhythms. A low melatonin level has been reported in individuals with autism spectrum disorders (ASD), but the underlying cause of this deficit was unknown. The ASMT gene, encoding the last enzyme of melatonin synthesis, is located on the pseudo-autosomal region 1 of the sex chromosomes, deleted in several individuals with ASD. In this study, we sequenced all ASMT exons and promoters in individuals with ASD (n=250) and compared the allelic frequencies with controls (n=255). Non-conservative variations of ASMT were identified, including a splicing mutation present in two families with ASD, but not in controls. Two polymorphisms located in the promoter (rs4446909 and rs5989681) were more frequent in ASD compared to controls (P=0.0006) and were associated with a dramatic decrease in ASMT transcripts in blood cell lines (P=2 x 10(-10)). Biochemical analyses performed on blood platelets and/or cultured cells revealed a highly significant decrease in ASMT activity (P=2 x 10(-12)) and melatonin level (P=3 x 10(-11)) in individuals with ASD. These results indicate that a low melatonin level, caused by a primary deficit in ASMT activity, is a risk factor for ASD. They also support ASMT as a susceptibility gene for ASD and highlight the crucial role of melatonin in human cognition and behavior.

Craniofacial and dental phenotype of Smith-Magenis syndrome

The aim of this study was to assess and characterize dental and craniofacial findings in individuals with a confirmed diagnosis of Smith-Magenis syndrome (SMS). Extraoral and intraoral examination including dental and craniofacial radiographs and three-dimensional facial photoimaging were performed for 15 cases between ages 4 and 19 years old. Tooth agenesis (13/15 cases) affecting primarily the mandibular second premolars and taurodontism (13/15 cases) were common findings. Dilaceration of the tooth roots was present in one-third of the cases. At least one dental anomaly was present in each case. These findings occur with greater frequency than in the general population (P < 0.001). An age-related increase in decayed and restored teeth was found. Poorer oral hygiene, increased dental plaque, and increased gingival inflammation progressed from childhood to teenage years. Radiographic findings suggest the prognathic appearance is not caused by excessive mandibular growth. Other findings including protrusion of the mandibular anterior teeth, increased bony chin size, and macroglossia were noted, which may contribute to the prognathic appearance. The high prevalence of dental anomalies (>90%) further expands the phenotype and indicates that dental evaluation may aid in the diagnosis of SMS.

Cytogenetic genotype-phenotype studies: improving genotyping, phenotyping and data storage

High-resolution molecular cytogenetic techniques such as genomic array CGH and MLPA detect submicroscopic chromosome aberrations in patients with unexplained mental retardation. These techniques rapidly change the practice of cytogenetic testing. Additionally, these techniques may improve genotype-phenotype studies of patients with microscopically visible chromosome aberrations, such as Wolf-Hirschhorn syndrome, 18q deletion syndrome and 1p36 deletion syndrome. In order to make the most of high-resolution karyotyping, a similar accuracy of phenotyping is needed to allow researchers and clinicians to make optimal use of the recent advances. International agreements on phenotype nomenclature and the use of computerized 3D face surface models are examples of such improvements in the practice of phenotyping patients with chromosomal anomalies. The combination of high-resolution cytogenetic techniques, a comprehensive, systematic system for phenotyping and optimal data storage will facilitate advances in genotype-phenotype studies and a further deconstruction of chromosomal syndromes. As a result, critical regions or single genes can be determined to be responsible for specific features and malformations.

Adaptive and maladaptive behavior in children with Smith-Magenis Syndrome

Children with Smith-Magenis Syndrome (SMS) exhibit deficits in adaptive behavior but systematic studies using objective measures are lacking. This descriptive study assessed adaptive functioning in 19 children with SMS using the Vineland Adaptive Behavior Scales (VABS). Maladaptive behavior was examined through parent questionnaires and the Childhood Autism Rating Scale. Cognitive functioning was evaluated with an age-appropriate test. Children scored below average on VABS Communication, Daily Living Skills, and Socialization scales. Learning problems and hyperactivity scales on the Conner's Parent Rating Scale were elevated, and girls were more impulsive than boys. Stereotypic and self-injurious behaviors were present in all children. Cognitive functioning was delayed and consistent with communication and daily living skills, while socialization scores were higher than IQ.

Inverted rhythm of melatonin secretion in Smith-Magenis syndrome: from symptoms to treatment

Smith-Magenis syndrome (SMS) is a mental retardation syndrome with distinctive behavioral characteristics, dysmorphic features and congenital anomalies ascribed to an interstitial deletion of chromosome 17p11.2. Severe sleep disturbances and maladaptative daytime behavior have been linked to an abnormal circadian secretion pattern of melatonin, with a diurnal instead of nocturnal secretion of this hormone. SMS provides a demonstration of a biological basis for sleep disorder in a genetic disease. Considering that clock genes mediate the generation of the circadian rhythm, haploinsufficiency for a circadian system gene, mapping to chromosome 17p11.2 might cause the inversion of the melatonin circadian rhythm in SMS. The disorder of circadian timing in SMS might also affect the entrainment pathway (retinohypothalamic tract), pacemaker functions (suprachiasmatic nucleus) or synthesis and release of melatonin by the pineal gland. Elucidating pathophysiological mechanisms of behavioral phenotypes in genetic disease can provide an original therapeutic approach in SMS: blockade of endogenous melatonin production during the day combined with exogenous melatonin administration in the evening.

Smith-Magenis syndrome: a case report of improved sleep after treatment with beta1-adrenergic antagonists and melatonin

This report describes the case of a 4-year-old boy diagnosed with Smith-Magenis syndrome in whom treatment with a beta(1)-adrenergic antagonist in the morning (to suppress the diurnal melatonin secretion) and melatonin in the evening (to generate a nocturnal peak of melatonin) improved his sleep quality, evaluated by polysomnographic studies.

Genotype–phenotype correlation in Smith-Magenis syndrome: Evidence that multiple genes in 17p11.2 contribute to the clinical spectrum

PURPOSE

Smith-Magenis syndrome (SMS) is a complex disorder that includes mental retardation, craniofacial and skeletal anomalies, and behavioral abnormalities. We report the molecular and genotype-phenotype analyses of 31 patients with SMS who carry 17p11.2 deletions or mutations in the RAI1 gene.

METHODS

Patients with SMS were evaluated by fluorescence in situ hybridization and/or sequencing of RAI1 to identify 17p11.2 deletions or intragenic mutations, respectively, and were compared for 30 characteristic features of this disorder by the Fisher exact test.

RESULTS

In our cohort, 8 of 31 individuals carried a common 3.5 Mb deletion, whereas 10 of 31 individuals carried smaller deletions, two individuals carried larger deletions, and one individual carried an atypical 17p11.2 deletion. Ten patients with nondeletion harbored a heterozygous mutation in RAI1. Phenotypic comparison between patients with deletions and patients with RAI1 mutations show that 21 of 30 SMS features are the result of haploinsufficiency of RAI1, whereas cardiac anomalies, speech and motor delay, hypotonia, short stature, and hearing loss are associated with 17p11.2 deletions rather than RAI1 mutations (P<.05). Further, patients with smaller deletions show features similar to those with RAI1 mutations.

CONCLUSION

Although RAI1 is the primary gene responsible for most features of SMS, other genes within 17p11.2 contribute to the variable features and overall severity of the syndrome.

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.

Cognitive and adaptive behavior profiles in Smith-Magenis syndrome

Smith-Magenis syndrome (SMS) is a multiple congenital anomalies and mental retardation syndrome associated with an interstitial deletion of chromosome 17 band p11.2. The incidence of this microdeletion syndrome is estimated to be 1 in 25,000 individuals. Persons with SMS have a distinctive neurobehavioral phenotype that is characterized by aggressive and self-injurious behaviors and significant sleep disturbances. From December 1990 through September 1999, 58 persons with SMS were enrolled in a 5-day multidisciplinary clinical protocol. Developmental assessments consisting of cognitive level and adaptive behavior were completed in 57 persons. Most patients functioned in the mild-to-moderate range of mental retardation. In addition, we report that patients with SMS have low adaptive functioning with relative strengths in socialization and relative weakness in daily living skills. These data were analyzed in light of the molecular extent of the microdeletion within 17p11.2. We found that the level of cognitive and adaptive functioning does depend on deletion size, and that a small percentage of SMS patients have cognitive function in the borderline range.

Neurologic and developmental features of the Smith-Magenis syndrome (del 17p11.2)

The Smith-Magenis syndrome is a rare, complex multisystemic disorder featuring, mental retardation and multiple congenital anomalies caused by a heterozygous interstitial deletion of chromosome 17p11.2. The phenotype of Smith-Magenis syndrome is characterized by a distinct pattern of features including infantile hypotonia, generalized complacency and lethargy in infancy, minor skeletal (brachycephaly, brachydactyly) and craniofacial features, ocular abnormalities, middle ear and laryngeal abnormalities including hoarse voice, as well as marked early expressive speech and language delays, psychomotor and growth retardation, and a 24-hour sleep disturbance. A striking neurobehavioral pattern of stereotypies, hyperactivity, polyembolokoilamania, onychotillomania, maladaptive and self-injurious and aggressive behavior is observed with increasing age. The diagnosis of Smith-Magenis syndrome is based upon the clinical recognition of a constellation of physical, developmental, and behavioral features in combination with a sleep disorder characterized by inverted circadian rhythm of melatonin secretion. Many of the features of Smith-Magenis syndrome are subtle in infancy and early childhood, and become more recognizable with advancing age. Infants are described as looking "cherubic" with a Down syndrome-like appearance, whereas with age the facial appearance is that of relative prognathism. Early diagnosis requires awareness of the often subtle clinical and neurobehavioral phenotype of the infant period. Speech delay with or without hearing loss is common. Most children are diagnosed in mid-childhood when the features of the disorder are most recognizable and striking. While improvements in cytogenetic analysis help to bring cases to clinical recognition at an earlier age, this review seeks to increase clinical awareness about Smith-Magenis syndrome by presenting the salient features observed at different ages including descriptions of the neurologic and behavioral features. Detailed review of the circadian rhythm disturbance unique to Smith-Magenis syndrome is presented. Suggestions for management of the behavioral and sleep difficulties are discussed in the context of the authors' personal experience in the setting of an ongoing Smith-Magenis syndrome natural history study.

Epilepsy and chromosomal rearrangements in Smith-Magenis Syndrome [del(17)(p11.2p11.2)]

Smith-Magenis syndrome is a multiple congenital anomalies/mental retardation syndrome associated with a heterozygous deletion of chromosome 17p11.2. Seizures have not been formally studied in this population. Our objectives were to estimate the prevalence of seizures and electroencephalographic (EEG) epileptiform abnormalities in patients with Smith-Magenis syndrome with defined chromosomal rearrangements and to describe the spectrum of abnormal EEG patterns. Prolonged video-EEGs were obtained in 60 patients. Eighteen percent of patients reported a seizure history; however, abnormal EEGs were identified in 31 of the 60 subjects and 27 of 31 were epileptiform. Generalized epileptiform patterns were the most common (73%). Most patients with either small or large deletions had an abnormal EEG (83%; 75%) in contrast to those with a common deletion (49%). Our results indicate that epileptiform EEG abnormalities are frequent in patients with Smith-Magenis syndrome. Considering that close to one third of individuals with Smith-Magenis syndrome with epileptiform abnormalities also had a history of clinical seizures, cortical hyperexcitability and epilepsy should be considered an important component of the Smith-Magenis syndrome clinical phenotype.

RAI1 variations in Smith-Magenis syndrome patients without 17p11.2 deletions

BACKGROUND

Smith-Magenis syndrome (SMS) (OMIM No 182290) is a mental retardation syndrome characterised by behavioural abnormalities, including self injurious behaviours, sleep disturbance, and distinct craniofacial and skeletal anomalies. It is usually associated with deletion involving 17p11.2 and is estimated to occur in 1/25,000 births. Heterozygous frameshift mutations leading to protein truncation in retinoic acid induced 1 gene (RAI1) have been identified in individuals with phenotypic features consistent with SMS. RAI1 lies within the 17p11.2 locus, but these patients did not have 17p11.2 deletions.

OBJECTIVE

Analysis of four individuals with features consistent with SMS for variations in RAI1, using a polymerase chain reaction and sequencing strategy. None of these patients carry 17p11.2 deletions.

RESULTS

Two patients had small deletions in RAI1 resulting in frameshift and premature truncation of the protein. Missense mutations were identified in the other two. Orthologs across other genomes showed that these missense mutations occurred in identically conserved regions of the gene. The mutations were de novo, as all parental samples were normal. Several polymorphisms were also observed, including new and reported SNPs. The patients' clinical features differed from those found in 17p11.2 deletion by general absence of short stature and lack of visceral anomalies. All four patients had developmental delay, reduced motor and cognitive skills, craniofacial and behavioural anomalies, and sleep disturbance. Seizures, not previously thought to be associated with RAI1 mutations, were observed in one patient of the cohort.

CONCLUSIONS

Haploinsufficiency of the RAI1 gene is associated with most features of SMS, including craniofacial, behavioural, and neurological signs and symptoms.

Chromosomal phenotypes and submicroscopic abnormalities

The finding, during the last decade, that several common, clinically delineated syndromes are caused by submicroscopic deletions or, more rarely, by duplications, has provided a powerful tool in the annotation of the human genome. Since most microdeletion/microduplication syndromes are defined by a common deleted/duplicated region, abnormal dosage of genes located within these regions can explain the phenotypic similarities among individuals with a specific syndrome. As such, they provide a unique resource towards the genetic dissection of complex phenotypes such as congenital heart defects, mental and growth retardation and abnormal behaviour. In addition, the study of phenotypic differences in individuals with the same microdeletion syndrome may also become a treasury for the identification of modifying factors for complex phenotypes. The molecular analysis of these chromosomal anomalies has led to a growing understanding of their mechanisms of origin. Novel tools to uncover additional submicroscopic chromosomal anomalies at a higher resolution and higher speed, as well as the novel tools at hand for deciphering the modifying factors and epistatic interactors, are 'on the doorstep' and will, besides their obvious diagnostic role, play a pivotal role in the genetic dissection of complex phenotypes.

Attention deficit/hyperactivity disorder (ADHD): complex phenotype, simple genotype?

Complex genetic traits refer to those phenotypes not fitting patterns of Mendelian segregation and/or assortment but exhibiting a preferential familial clustering that cannot be explained by cultural or environmental causes. Attention-deficit/hyperactivity disorder (ADHD) is the most common neurodevelopmental disorder of childhood and probably the most controversial. ADHD has been considered a complex genetic trait based upon the absence of a clear-cut boundary between affected and unaffected status. Furthermore, its high comorbidity with other disorders strongly suggests complex epistatic or pleiotropic effects acting in common with the environmental influences. This implies that the same gene or genes is or are associated with different and concurrently occurring phenotypes. In this study, we will review clinical and epidemiological aspects related to the ADHD phenotype, which are considered either as categorical or continuous traits. We also will discuss genetic models underlying the complexity of this behavioral phenotype and the probable role of epistatic interactions between major genes contributing to the ADHD phenotype.

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.

Neurologic disorders masquerading as pediatric sleep problems

Neurologic disorders may present or masquerade as pediatric sleep problems and fool the pediatrician, which may delay diagnosis and treatment. Many of the sleep problems in children with neurologic disorders arise directly from primary dysfunction or delayed maturation of their sleep-wake regulation systems. It is important to realize that nocturnal frontal lobe seizures or cluster headaches can be mistaken for night terrors, and craniopharyngiomas or myotonic dystrophy may present as narcolepsy-cataplexy. Hypothalamic dysfunction may explain not only the impaired circadian rhythm disorders in children with profound mental retardation but also excessive sleepiness and hyperphagia in Prader-Willi and Kleine-Levin syndromes. Intellectually challenged children perform better, learn more, and are better behaved with sufficient restorative sleep.

Self-injurious behavior in young boys with fragile X syndrome

In this study, we distributed surveys to 67 families of young boys with fragile X syndrome to determine the prevalence, onset, form, function, location, and correlates of self-injurious behavior. Fifty-five surveys were completed (82%). The mean age of the boys at the time of the survey was 80 months (range = 20-144). Self-injurious behavior (SIB) was reported for 58% of the participants with a mean age of onset of 31 months. The mean number of forms of self-injury was 2 per participant. Biting was the most commonly reported form of self-injury with the fingers and back of the hand disproportionately targeted as the most prevalent self-injury body site. There was no linear increase in risk of SIB with age past 25 months. SIB was reported as most likely to occur following the presentation of difficult task demands or changes in routine. Significant group differences were found between overall ratings of problem behavior for boys with self-injury compared to those without self-injury. Groups did not differ on measures of fragile X mental retardation protein (FMRP), autism status, adaptive behavior, or age first medicated. Results are discussed in terms of future research designed to further elucidate the behavioral phenotype of fragile X syndrome.

Mutations in RAI1 associated with Smith-Magenis syndrome

Smith-Magenis syndrome (SMS) is a mental retardation syndrome associated with deletions involving chromosome 17p11.2. Persons with SMS have characteristic behavioral abnormalities, including self-injurious behaviors and sleep disturbance, and distinct craniofacial and skeletal anomalies. We identified dominant frameshift mutations leading to protein truncation in RAI1 in three individuals who have phenotypic features consistent with SMS but do not have 17p11.2 deletions detectable by standard fluorescence in situ hybridization techniques.

Hypercholesterolemia in children with Smith-Magenis syndrome: del (17) (p11.2p11.2)

PURPOSE

Smith-Magenis syndrome (SMS), a probable contiguous gene syndrome due to an interstitial deletion of chromosome 17 band p11.2, is associated with a distinct and complex phenotype, including physical, developmental, and neurobehavioral features. The majority of SMS patients are deleted for a common approximately 4 Mb interval that includes the gene SREBF1, a transmembrane transcription factor that regulates the low density lipoprotein (LDL) receptor and plays a crucial role in cholesterol homeostasis. A systematic study of fasting lipid profiles of patients with SMS was conducted to determine the frequency of cholesterol abnormalities.

METHODS

Fasting lipid profiles were examined in 49 children (27F/22M) between the ages of 0.6 years to 17.6 years (mean, 6.9 years) with a cytogenetically confirmed diagnosis of SMS. Observed values for serum total cholesterol (TC), triglycerides (TG), LDL cholesterol, and high density lipoprotein cholesterol were compared with published norms. The body mass index (BMI) was used as a measure of nutritional status.

RESULTS

Mean TC was significantly higher than published NHANES III pediatric norms (P < 0.0008). Overall 28 of 49 (57%) SMS subjects had lipid values greater than the 95th percentile for age and gender for at least one or more of the following: TC, TG, and/or LDL. Only 16 SMS subjects (32%) were within normal limits for all three of these variables. BMI values showed minimal positive correlation to SMS lipid values; however, no consistent effect was found. Thus BMI values alone do not explain the marked trend in increased TC, TG, and/or LDL observed in the SMS group. Based on the American Academy of Pediatrics recommended lipid levels for children and adolescents, only one third of SMS subjects fall within normal range for TC and LDL; an additional one third each measure "borderline" or "high" for these values.

CONCLUSION

Hypercholesterolemia is common in SMS and may serve as a useful early clinical biochemical marker of the syndrome.

beta(1)-adrenergic antagonists improve sleep and behavioural disturbances in a circadian disorder, Smith-Magenis syndrome

Smith-Magenis syndrome (SMS) is a clinically recognisable contiguous gene syndrome ascribed to interstitial deletions of chromosome 17p11.2. Patients have a phase shift of their circadian rhythm of melatonin with a paradoxical diurnal secretion of the hormone. Serum melatonin levels and day-night behaviour were studied in nine SMS children (aged 4 to 17 years) given acebutolol, a selective beta(1)-adrenergic antagonist (10 mg/kg early in the morning). Cardiac examination, serum melatonin, motor activity recordings, and sleep diaries were monitored before and after drug administration. The present study shows that a single morning dose of acebutolol suppressed the inappropriate secretion of melatonin in SMS. A significant improvement of inappropriate behaviour with increased concentration, delayed sleep onset, increased hours of sleep, and delayed waking were also noted. These results suggest that beta(1)-adrenergic antagonists help to manage hyperactivity, enhance cognitive performance, and reduce sleep disorders in SMS.

Inversion of the circadian rhythm of melatonin in the Smith-Magenis syndrome

OBJECTIVE

The objective was to determine the circadian rhythm of melatonin in the Smith-Magenis syndrome (SMS), which causes behavioral problems and sleep disturbance.

STUDY DESIGN

Questionnaires, sleep consultations, and sleep diaries were obtained in 20 children with SMS (9 girls, 11 boys aged 4 to 17 years). Actigraphy, electroencephalography, and the circadian variations of plasma melatonin, cortisol, and growth hormone were recorded in 8 patients. Early sleep onset, early sleep offset, and sleep attack indicated sleep disturbance.

RESULTS

All children with SMS had a phase shift of their circadian rhythm of melatonin. Time at onset of melatonin secretion was 6 AM +/- 2 (control group: 9 P.M. +/- 2). Peak time was 12 PM +/- 1 (control group: 3:30 AM +/- 1:30), and melatonin offset was at 8 PM +/- 1 (control group: 6 AM +/- 1). Behavioral problems correlated with the inverted circadian rhythm of melatonin.

CONCLUSION

Considering that clock genes mediate the generation of circadian rhythms, we suggest that haploinsufficiency for a circadian system gene mapping to chromosome 17p11.2 may cause the inversion of the circadian rhythm of melatonin in SMS.

Behavioral phenotypes of genetic syndromes: a reference guide for psychiatrists

OBJECTIVE

To review the literature on behavioral phenotypes of genetic syndromes, displaying the data as a reference guide for everyday practice.

METHOD

A computerized search was performed for articles published in the past 10 years, and selected papers were surveyed.

RESULTS

The behavioral phenotypes of 11 major genetic syndromes were reviewed including the following topics: genetic etiology, genetic counseling, physical features, medical problems, cognitive and behavioral profile, and psychopathology. The speculated correlation between the identified gene and the pathophysiology of the cognitive and behavioral features is discussed.

CONCLUSIONS

Updated knowledge of behavioral phenotypes will help psychiatrists identify these conditions, refer the patient and his/her family for genetic diagnosis and counseling, make specific treatment recommendations, and contribute to research and syndrome delineation.

Otorhinolaringologic manifestation of Smith-Magenis syndrome

Smith-Magenis syndrome (SMS) is a multiple congenital anomaly/mental retardation (MCA/MR) syndrome link to a contiguous-gene deletion syndrome, involving chromosome 1 7p 11.2,whose incidence is estimated to be 1:25,000 livebirth. SMS is characterised by a specific physical, behavioural and developmental pattern. The main clinical features consist of a broad flat midface with brachycefaly, broad nasal bridge, brachydactily, speech delay, hoarse deep voice and peripheral neuropathy. Behavioural abnormalities include hypermotility, self-mutilation and sleep disturbance. This report defines the otorhinolaryngological aspects of a new case of SMS, confirmed by cytogenetic-molecular analysis, in a 9 year old girl affected by chronic otitis media, deafness and sinusitis, who presented with typical clinical signs and symptoms.

Patient with large 17p11.2 deletion presenting with Smith-Magenis syndrome and Joubert syndrome phenotype

We report on a 22-year-old woman carrying a del(17)(p11.2p12) and presenting with the clinical manifestations of both Smith-Magenis syndrome (SMS) and Joubert syndrome (JS). Her facial anomalies, brachydactyly, severe mental retardation, and self-injuring behavior could be attributed to SMS, whereas the cerebellar vermis hypoplasia, hypotonia, ataxic gait, developmental delay, and abnormal respiratory pattern were suggestive of JS. By fluorescent in situ hybridization analyses with Yeast Artificial Chromosomes (YAC) mapping to the 17p11.2 region, as well as locus-specific probes generated through a novel procedure, we could establish that the deletion encompasses a 4-Mb interval with centromeric and telomeric breakpoints at loci D17S793 and D17S953, the latter close to the locus Charcot Marie Tooth 1A (CMT1A)-REP. The deletion differs from that commonly found in SMS in its telomeric boundary, which is more distal than usually observed. The presence of JS phenotype in our patient and the detection of an unusual SMS deletion might suggest the presence of a JS gene in close proximity to the SMS locus.

Genetic evaluation of pervasive developmental disorders: the terminal 22q13 deletion syndrome may represent a recognizable phenotype

The evaluation of mental retardation is always a challenge to clinicians. The recognition of specific physical or behavioral characteristics can vastly improve diagnostic yield. Several genetic disorders have been identified to have certain behavioral characteristics, such as Williams syndrome, Smith-Magenis syndrome, and the velocardiofacial syndrome (VCFS). The deletion affecting the chromosome 22q in the most distal band (22q13) appears to define yet another neurobehavioral phenotype. In addition to our report, there are about 17 other cases published of this particular deletion syndrome. We describe three children who share features of developmental delay and pervasive behaviors in addition to normal to advanced growth patterns. Results of cytogenetic analysis suggest that the 3 patients share a deletion affecting the terminal 22q13 region. Two were found to have a cryptic deletion, in the third it was detected by conventional cytogenetics. The cryptic deletions were demonstrated using fluorescent in situ hybridization (FISH), where the control probe for the DiGeorge/VCFS region was deleted. While there remain gaps in our understanding of this particular deletion syndrome, we propose that patients with normal or advanced growth, significantly delayed speech, deviant development and pervasive behaviors, with minor facial dysmorphism, be screened for this deletion.

The face of Smith-Magenis syndrome: a subjective and objective study

We report a study of 55 subjects with Smith-Magenis syndrome, aged 9 months to 35 years. Each person has been evaluated with an assessment of “gestalt” and detailed facial measurement, using previously published methodology, with compilation of Z score pattern profiles.

The facial phenotype of SMS is quite distinctive, even in the young child. The overall face shape is broad and square. The brows are heavy, with excessive lateral extension of the eyebrows. The eyes slant upwards and appear close set and deep set. The nose has a depressed root and, in the young child, a scooped bridge. With time, the bridge becomes more ski jump shaped. The height of the nose is markedly reduced while the nasal base is broad and the tip of the nose is full. The shape of the mouth and upper lip are most distinctive. The mouth is wide with full upper and lower lips. The central portion of the upper lip is fleshy and everted with bulky philtral pillars, producing a tented appearance that, in profile, is striking. With age, mandibular growth is greater than average and exceeds that of the maxilla. This leads to increased jaw width and protrusion and marked midface hypoplasia.

Craniofacial pattern analysis supports these subjective impressions. After mid-childhood, mandibular dimensions consistently exceed their maxillary counterparts. Craniofacial widths are greater than corresponding depths and heights. Nasal height is reduced while nasal width is increased. There is mild brachycephaly. The most marked age related changes are increased width of the nose and lower face (mandibular width) with reduction in nasal height and midfacial depth.

Case study: carbamazepine treatment of juvenile-onset bipolar disorder

The literature devoted to juvenile-onset bipolar disorder has rapidly expanded in the past 5 years with an emphasis on new concepts of prevalence and comorbid conditions. In the process of enlarging the knowledge base about the phenomenology of juvenile-onset bipolar disorder, this new literature has generated considerable controversy but has provided little information about pharmacotherapy. In the following case series, carbamazepine appeared to be a safe and effective treatment for juvenile-onset bipolar disorder. Controlled studies are necessary before any definitive conclusions can be reached about the efficacy of carbamazepine in the treatment of this form of bipolar disorder.

Transcription mapping in a medulloblastoma breakpoint interval and Smith-Magenis syndrome candidate region: identification of 53 transcriptional units and new candidate genes

The chromosomal band 17p11.2 is associated with a number of neurological disorders and malignant diseases. This region is also characterized by the presence of complex repeat elements that are probably responsible for the frequent occurrence of interstitial deletions, duplications, and isochromosome formation. In the course of the molecular analysis of this interval, an integrated map with YACs, PACs, and cosmids covering approximately 6 Mb was established. Focusing on the 1.4-Mb interval containing the Smith-Magenis syndrome critical region and the breakpoint region for medulloblastomas, we constructed a detailed transcript map between the marker PS2 and the proximal CMT1A repeat. FISH analysis of the PACs allowed determination of the position of the transcripts with respect to the SMS critical region and the presumptive chromosomal breakpoint in medulloblastomas. One PAC (G21100) provided evidence for the presence of a novel complex repeat unit, indicating that there are at least three independent repeat elements within 2 Mb. Five genes were mapped to clone G21100 and are likely to form part of this novel complex sequence repeat. In summary, 53 new transcripts were isolated by using cDNA selection and exon trapping. This included 8 known but previously unmapped genes and 45 novel transcripts. The expression profile of 21 transcripts was determined by RT-PCR. Based on their homologies to known genes or proteins, some of the novel genes are considered candidate genes either for malignant diseases or for the Smith-Magenis syndrome.