[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.
UDEIP, centre de dépistage et de prise en charge des troubles psychiatriques d'origine génétique, centre hospitalier le Vinatier, 95, boulevard Pinel, 69678 Bron cedex, France; Centre de neurosciences cognitives, UMR 5229 CNRS, 69500 Bron, France; Université Lyon 1, 69500 Lyon, France. Electronic address: alice.poisson@ch-le-vinatier.fr.
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Poisson
UDEIP, centre de dépistage et de prise en charge des troubles psychiatriques d'origine génétique, centre hospitalier le Vinatier, 95, boulevard Pinel, 69678 Bron cedex, France; Université Lyon 1, 69500 Lyon, France.
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Nicolas
Université Lyon 1, 69500 Lyon, France; Service de génétique, centre des anomalies du développement, laboratoire de cytogénétique, hospices civils de Lyon, 69500 Bron, France.
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Sanlaville
Université Lyon 1, 69500 Lyon, France; Service de néphrologie et rhumatologie pédiatrique, centre de référence des maladies rénales rares, Inserm U820, hospices civils de Lyon, 69500 Bron, France.
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Cochat
Centre de recherche en neurosciences de Lyon, Inserm U1028, CNRS UMR 5292, UCBL, équipe TIGER, 69500 Bron, France.
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De Leersnyder
UDEIP, centre de dépistage et de prise en charge des troubles psychiatriques d'origine génétique, centre hospitalier le Vinatier, 95, boulevard Pinel, 69678 Bron cedex, France; Centre de neurosciences cognitives, UMR 5229 CNRS, 69500 Bron, France.
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Rigard
Université Lyon 1, 69500 Lyon, France; Unité d'hypnologie, service de neuropédiatrie, Inserm U 628, hospices civils de Lyon, 69500 Bron, France.
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Franco
Université Lyon 1, 69500 Lyon, France; Centre de référence X fragile et autres déficiences intellectuelles de causes rares, hospices civils de Lyon, 69500 Bron, France.
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des Portes
Service de génétique, centre de référence des anomalies du développement et des syndromes malformatifs, hospices civils de Lyon, 69500 Bron, France; Université Lyon 1, 69500 Lyon, France; Centre de référence X fragile et autres déficiences intellectuelles de causes rares, hospices civils de Lyon, 69500 Bron, France.
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Edery
UDEIP, centre de dépistage et de prise en charge des troubles psychiatriques d'origine génétique, centre hospitalier le Vinatier, 95, boulevard Pinel, 69678 Bron cedex, France; Centre de neurosciences cognitives, UMR 5229 CNRS, 69500 Bron, France; Université Lyon 1, 69500 Lyon, France.
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Demily
D002648:Child; D006801:Humans; D001523:Mental Disorders / Q000175:diagnosis / Q000235:genetics; D010641:Phenotype; D020178:Sleep Disorders, Circadian Rhythm / Q000175:diagnosis / Q000235:genetics; D058496:Smith-Magenis Syndrome / Q000175:diagnosis / Q000235:genetics