Ophthalmic manifestations of Smith-Magenis syndrome

Deletion of cis-regulatory Element in FOXL2 Promoter in a Chinese Family of Type II Blepharophimosis-ptosis-epicanthus Inversus Syndrome with Polydactyly

Blepharophimosis-ptosis-epicanthus inversus syndrome (BPES) is a relatively uncommon autosomal-dominant genetic disorder, primarily attributed to mutations in the forkhead box L2 (FOXL2) gene. Albeit the involvement of protein-coding regions of FOXL2 has been observed in the majority of BPES cases, whether deficiencies in regulatory elements lead to the pathogenesis remains poorly understood. Herein, an autosomal-dominant BPES type II family was included. Peripheral venous blood has been collected, and genomic DNA has been extracted from leukocytes. A whole exome sequencing analysis has been performed and analyzed (Deposited in NODE database: OER422653). The promoter region of FOXL2 was amplified using polymerase chain reaction (PCR). The luciferase reporter assay was performed to identify the activity of this region. In this study, we present a Chinese family diagnosed with type II BPES, characterized by the presence of small palpebral fissures, ptosis, telecanthus, and epicanthus inversus. Notably, all male individuals within the family display polydactyly. A 225-bp deletion in the 556-bp 5'-upstream to transcription start site of FOXL2 , decorated by multiple histone modifications, was identified in affected members of the family. This deletion significantly decreased FOXL2 promoter activity, as measured by the luciferase assay. Conclusively, a novel 255-bp-deletion of the FOXL2 promoter was identified in Chinese families with BPES. Our results expand the spectrum of known FOXL2 mutations and provide additional insight into the genotype-phenotype relationships of the BPES pathogenesis. In addition, this study indicates the important role of genetic screening of cis-regulatory elements in testing heritable diseases.

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.

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.

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.

Smith-Magenis Syndrome: Face Speaks

Smith-Magenis syndrome is a well delineated microdeletion syndrome with characteristic facial and behavioral phenotype. With the availability of the multi-targeted molecular cytogenetic techniques like Multiplex Ligation Probe Amplification and cytogenetic microarray, the cases are diagnosed even without clinical suspicion. Here, the authors present clinical features of nine Indian cases of Smith-Magenis syndrome. Characteristic facial phenotype including tented upper lip, broad forehead, midface hypoplasia, short philtrum and upslant of palpebral fissure is obvious in the photographs. The behavioral variations were seen in some of the cases but were not the presenting features. The characteristic facial phenotype can be an important clinical guide to the diagnosis.

Neurodevelopmental Disorders Associated with Abnormal Gene Dosage: Smith-Magenis and Potocki-Lupski Syndromes

Smith-Magenis syndrome (SMS) and Potocki-Lupski syndrome (PTLS) are reciprocal contiguous gene syndromes within the well-characterized 17p11.2 region. Approximately 3.6 Mb microduplication of 17p11.2, known as PTLS, represents the mechanistically predicted homologous recombination reciprocal of the SMS microdeletion, both resulting in multiple congenital anomalies. Mouse model studies have revealed that the retinoic acid-inducible 1 gene (RAI1) within the SMS and PTLS critical genomic interval is the dosage-sensitive gene responsible for the major phenotypic features in these disorders. Even though PTLS and SMS share the same genomic region, clinical manifestations and behavioral issues are distinct and in fact some mirror traits may be on opposite ends of a given phenotypic spectrum. We describe the neurobehavioral phenotypes of SMS and PTLS patients during different life phases as well as clinical guidelines for diagnosis and a multidisciplinary approach once diagnosis is confirmed by array comparative genomic hybridization or RAI1 gene sequencing. The main goal is to increase awareness of these rare disorders because an earlier diagnosis will lead to more timely developmental intervention and medical management which will improve clinical outcome.

Behavioral disturbance and treatment strategies in Smith-Magenis syndrome

Background

Smith-Magenis syndrome is a complex neurodevelopmental disorder that includes intellectual deficiency, speech delay, behavioral disturbance and typical sleep disorders. Ninety percent of the cases are due to a 17p11.2 deletion encompassing the RAI1 gene; other cases are linked to mutations of the same gene. Behavioral disorders often include outbursts, attention deficit/hyperactivity disorders, self-injury with onychotillomania and polyembolokoilamania (insertion of objects into body orifices), etc. Interestingly, the stronger the speech delay and sleep disorders, the more severe the behavioral issues. Sleep disturbances associate excessive daytime sleepiness with nighttime agitation. They are underpinned by an inversion of the melatonin secretion cycle. However, the combined intake of beta-blockers in the morning and melatonin in the evening may radically alleviate the circadian rhythm problems.

Discussion

Once sleep disorders are treated, the next challenge is finding an effective treatment for the remaining behavioral problems. Unfortunately, there is a lack of objective guidelines. A comprehensive evaluation of such disorders should include sleep disorders, potential causes of pain, neurocognitive level and environment (i.e. family and school). In any case, efforts should focus on improving communication skills, identifying and treating attention deficit/hyperactivity, aggressiveness and anxiety.

Summary

Treatment of Smith-Magenis syndrome is complex and requires a multidisciplinary team including, among others, geneticists, psychiatrists, neuropediatricians/neurologists, somnologists, developmental and behavioral pediatricians, and speech and language therapists.

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.

[Smith-Magenis syndrome is an association of behavioral and sleep/wake circadian rhythm disorders]

Smith-Magenis syndrome (SMS) is a genetic disorder characterized by the association of facial dysmorphism, oral speech delay, as well as behavioral and sleep/wake circadian rhythm disorders. Most SMS cases (90%) are due to a 17p11.2 deletion encompassing the RAI1 gene; other cases stem from mutations of the RAI1 gene. Behavioral issues may include frequent outbursts, attention deficit/hyperactivity disorders, self-injuries with onychotillomania and polyembolokoilamania (insertion of objects into bodily orifices), etc. It is noteworthy that the longer the speech delay and the more severe the sleep disorders, the more severe the behavioral issues are. Typical sleep/wake circadian rhythm disorders associate excessive daytime sleepiness with nocturnal agitation. They are related to an inversion of the physiological melatonin secretion cycle. Yet, with an adapted therapeutic strategy, circadian rhythm disorders can radically improve. Usually an association of beta-blockers in the morning (stops daily melatonin secretion) and melatonin in the evening (mimics the evening deficient peak) is used. Once the sleep disorders are controlled, effective treatment of the remaining psychiatric features is needed. Unfortunately, as for many orphan diseases, objective guidelines have not been drawn up. However, efforts should be focused on improving communication skills. In the same vein, attention deficit/hyperactivity disorders, aggressiveness, and anxiety should be identified and specifically treated. This whole appropriate medical management is underpinned by the diagnosis of SMS. Diagnostic strategies include fluorescent in situ hybridization (FISH) or array comparative genomic hybridization (array CGH) when a microdeletion is sought and Sanger sequencing when a point mutation is suspected. Thus, the diagnosis of SMS can be made from a simple blood sample and should be questioned in subjects of any age presenting with an association of facial dysmorphism, speech delay with behavioral and sleep/wake circadian rhythm disorders, and other anomalies including short stature and mild dysmorphic features.

Disruption of MBD5 contributes to a spectrum of psychopathology and neurodevelopmental abnormalities

Microdeletions of chromosomal region 2q23.1 that disrupt MBD5 (methyl-CpG-binding domain protein 5) contribute to a spectrum of neurodevelopmental phenotypes; however, the impact of this locus on human psychopathology has not been fully explored. To characterize the structural variation landscape of MBD5 disruptions and the associated human psychopathology, 22 individuals with genomic disruption of MBD5 (translocation, point mutation and deletion) were identified through whole-genome sequencing or cytogenomic microarray at 11 molecular diagnostic centers. The genomic impact ranged from a single base pair to 5.4 Mb. Parents were available for 11 cases, all of which confirmed that the rearrangement arose de novo. Phenotypes were largely indistinguishable between patients with full-segment 2q23.1 deletions and those with intragenic MBD5 rearrangements, including alterations confined entirely to the 5'-untranslated region, confirming the critical impact of non-coding sequence at this locus. We identified heterogeneous, multisystem pathogenic effects of MBD5 disruption and characterized the associated spectrum of psychopathology, including the novel finding of anxiety and bipolar disorder in multiple patients. Importantly, one of the unique features of the oldest known patient was behavioral regression. Analyses also revealed phenotypes that distinguish MBD5 disruptions from seven well-established syndromes with significant diagnostic overlap. This study demonstrates that haploinsufficiency of MBD5 causes diverse phenotypes, yields insight into the spectrum of resulting neurodevelopmental and behavioral psychopathology and provides clinical context for interpretation of MBD5 structural variations. Empirical evidence also indicates that disruption of non-coding MBD5 regulatory regions is sufficient for clinical manifestation, highlighting the limitations of exon-focused assessments. These results suggest an ongoing perturbation of neurological function throughout the lifespan, including risks for neurobehavioral regression.

Smith–Magenis syndrome: haploinsufficiency of RAI1 results in altered gene regulation in neurological and metabolic pathways

Smith–Magenis syndrome (SMS) is a complex neurobehavioural disorder characterised by intellectual disability, self-injurious behaviours, sleep disturbance, obesity, and craniofacial and skeletal anomalies. Diagnostic strategies are focused towards identification of a 17p11.2 microdeletion encompassing the gene RAI1 (retinoic acid induced 1) or a mutation of RAI1. Molecular evidence shows that most SMS features are due to RAI1 haploinsufficiency, whereas variability and severity are modified by other genes in the 17p11.2 region for 17p11.2 deletion cases. The functional role of RAI1 is not completely understood, but it is probably a transcription factor acting in several different biological pathways that are dysregulated in SMS. Functional studies based on the hypothesis that RAI1 acts through phenotype-specific pathways involving several downstream genes have shown that RAI1 gene dosage is crucial for normal regulation of circadian rhythm, lipid metabolism and neurotransmitter function. Here, we review the clinical and molecular features of SMS and explore more recent studies supporting possible therapeutic strategies for behavioural management.

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.

Gender, genotype, and phenotype differences in Smith-Magenis syndrome: a meta-analysis of 105 cases

Smith-Magenis syndrome (SMS) is a multisystem disorder characterized by developmental delay and mental retardation, a distinctive behavioral phenotype, and sleep disturbance. We undertook a comprehensive meta-analysis to identify genotype-phenotype relationships to further understand the clinical variability and genetic factors involved in SMS. Clinical and molecular information on 105 patients with SMS was obtained through research protocols and a review of the literature and analyzed using Fisher's exact test with two-tailed p values. Several differences in these groups of patients were identified based on genotype and gender. Patients with RAI1 mutation were more likely to exhibit overeating, obesity, polyembolokoilamania, self-hugging, muscle cramping, and dry skin and less likely to have short stature, hearing loss, frequent ear infections, and heart defects when compared with patients with deletion, while a subset of small deletion cases with deletions spanning from TNFRSF13B to MFAP4 was less likely to exhibit brachycephaly, dental anomalies, iris abnormalities, head-banging, and hyperactivity. Significant differences between genders were also identified, with females more likely to have myopia, eating/appetite problems, cold hands and feet, and frustration with communication when compared with males. These results confirm previous findings and identify new genotype-phenotype associations including differences in the frequency of short stature, hearing loss, ear infections, obesity, overeating, heart defects, self-injury, self-hugging, dry skin, seizures, and hyperactivity among others based on genotype. Additional studies are required to further explore the relationships between genotype and phenotype and any potential discrepancies in health care and parental attitudes toward males and females with SMS.

New developments in Smith-Magenis syndrome (del 17p11.2)

PURPOSE OF REVIEW

Recent clinical, neuroimaging, sleep, and molecular cytogenetic studies have provided new insights into the mechanisms leading to the Smith-Magenis phenotype and are summarized in this review.

RECENT FINDINGS

Cross sectional studies of patients with Smith-Magenis syndrome have found evidence for central and peripheral nervous system abnormalities, neurobehavioral disturbances, and an inverted pattern of melatonin secretion leading to circadian rhythm disturbance. A common chromosome 17p11.2 deletion interval spanning approximately 3.5 Mb is identified in about 70% of individuals with chromosome deletion. Recently heterozygous point mutations in the RAI1 gene within the Smith-Magenis syndrome critical region have been reported in Smith-Magenis syndrome patients without detectable deletion by fluorescent in-situ hybridization. Patients with intragenic mutations in RAI1 as well as those with deletions share most but not all aspects of the phenotype.

SUMMARY

Findings from molecular cytogenetic analysis suggest that other genes or genetic background may play a role in altering the functional availability of RAI1 for downstream effects. Further research into additional genes in the Smith-Magenis syndrome critical region will help define the role they play in modifying features or severity of the Smith-Magenis syndrome phenotype. More research is needed to translate advances in clinical research into new treatment options to address the sleep and neurobehavioral problems in this disorder.

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.

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.

Diurnal mice (Mus musculus) and other examples of temporal niche switching

Examples are presented of nocturnal animals becoming diurnal or vice versa as a result of mutations, genetic manipulations, or brain lesions. Understanding these cases could give insight into mechanisms employed when switches of temporal niche occur as part of the life cycle, or in response to circumstances such as availability of food. A two-process account of niche switching is advocated, involving both a change in clock-controlled outputs and a change in the direct response to light (i.e. masking). An emerging theme from this review is the suggestion that retinal inputs have a greater role in switching than suspected previously.

Variability in clinical phenotype despite common chromosomal deletion in Smith-Magenis syndrome [del(17)(p11.2p11.2)]

PURPOSE

This report delineates the phenotypic features in a cohort of 58 individuals with Smith-Magenis syndrome (SMS) and compares features of patients with the common microdeletion to those of patients with variable sized deletions, and the three previously reported patients who harbor a mutation in RAI1 (retinoic acid induced 1).

METHODS

From December 1990 thru September 1999, 58 persons with SMS were enrolled in a 5-day multidisciplinary clinical protocol at the General Clinical Research Center (GCRC), Texas Children's Hospital. Each patient had a cytogenetically evident deletion in 17p11.2.

RESULTS

Of the 51 patients in whom the molecular extent of the chromosomal deletion could be delineated by pulsed-field gel electrophoresis (PFGE) and/or fluorescent in situ hybridization (FISH), 39 (approximately 76%) had the common SMS deletion. Smaller or larger deletions were seen in approximately 12% and approximately 10% of patients, respectively, and 1 patient had a complex chromosomal rearrangement including a deletion in 17p11.2. Parent of origin was determined by polymorphic marker analysis in a subset of patients: maternal approximately 43%, paternal approximately 57%. All patients had impaired cognitive and adaptive functioning and had at least one objective measure of sleep disturbance. Other common features (seen in >50% of patients) include short stature, ophthalmological, and otolaryngological anomalies, hearing impairment, abnormal EEG, and scoliosis. Cardiac and renal anomalies were seen in approximately 45% and approximately 19% of patients, respectively. There are no statistically significant differences in the incidence of these abnormalities in patients with the common deletion compared to those patients with smaller or larger sized deletions.

CONCLUSIONS

Despite a common deletion size in 76% of patients with SMS, the only constant objectively defined features among these patients are sleep disturbances, low adaptive functioning, and mental retardation. There is no pathognomonic clinical feature, no characteristic cardiovascular defect, renal anomaly, otolaryngological or ophthalmic abnormality in SMS.

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.

DNA rearrangements on both homologues of chromosome 17 in a mildly delayed individual with a family history of autosomal dominant carpal tunnel syndrome

Disorders known to be caused by molecular and cytogenetic abnormalities of the proximal short arm of chromosome 17 include Charcot-Marie-Tooth disease type 1A (CMT1A), hereditary neuropathy with liability to pressure palsies (HNPP), Smith-Magenis syndrome (SMS), and mental retardation and congenital anomalies associated with partial duplication of 17p. We identified a patient with multifocal mononeuropathies and mild distal neuropathy, growth hormone deficiency, and mild mental retardation who was found to have a duplication of the SMS region of 17p11.2 and a deletion of the peripheral myelin protein 22 (PMP22) gene within 17p12 on the homologous chromosome. Further molecular analyses reveal that the dup(17)(p11.2p11.2) is a de novo event but that the PMP22 deletion is familial. The family members with deletions of PMP22 have abnormalities indicative of carpal tunnel syndrome, documented by electrophysiological studies prior to molecular analysis. The chromosomal duplication was shown by interphase FISH analysis to be a tandem duplication. These data indicate that familial entrapment neuropathies, such as carpal tunnel syndrome and focal ulnar neuropathy syndrome, can occur because of deletions of the PMP22 gene. The co-occurrence of the 17p11.2 duplication and the PMP22 deletion in this patient likely reflects the relatively high frequency at which these abnormalities arise and the underlying molecular characteristics of the genome in this region.

Visual impairment due to macular disciform scars in a 20-year-old man with Smith-Magenis syndrome: another ophthalmologic complication

We describe a 20-year-old man with Smith-Magenis syndrome and a 46,XY,del(17)(p11.2p11.2) karyotype. The interstitial deletion was confirmed by metaphase analysis using the fluorescent in situ hybridization probe (D17S29) for the Smith-Magenis region. The patient had hypertelorism, exotropia, and high myopia. Examination under anesthesia showed a lacquer crack near the right macula and a disciform scar of the left macula. Six months later, the patient presented with subacute visual loss. Examination demonstrated end-stage macula degeneration with bilateral disciform scars. There was no evidence of retinal detachment. Prior reports of Smith-Magenis syndrome mention telecanthus, ptosis, strabismus, iris anomalies, cataract, microcornea, optic nerve hypoplasia, myopia, retinal detachment, and lattice retinal degeneration. Bilateral macular degeneration has not been reported previously, and it may be an additional ophthalmologic manifestation of Smith-Magenis syndrome, either as a primary manifestation or as a direct consequence of high myopia.

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

Smith-Magenis syndrome (SMS) is a distinct and clinically recognizable multiple congenital anomaly (MCA) and mental retardation syndrome caused by an interstitial deletion of chromosome 17 p11.2. The phenotype of SMS has been well described and includes: a characteristic pattern of physical features; a hoarse, deep voice; speech delay with or without associated hearing loss; signs of peripheral neuropathy; variable levels of mental retardation; and neurobehavioral problems. Although self-injury and sleep disturbance are major problems in SMS, studies are limited on the behavioral phenotype of SMS. This report reviews the current state of knowledge about SMS and presents new data based on syndrome-specific observations by the authors' longitudinal experience working with SMS, specifically related to the behavioral aspects of SMS. This information should have relevance for parents, clinicians, geneticists, and educators involved in the care of individuals with SMS.