Original article Cognitive functioning in children and adults with Smith-Magenis syndrome Ana Osório a,1 , Raquel Cruz b, c,1 , Adriana Sampaio a , Elena Garayzábal d , Ángel Carracedo b, c, e , Montse Fernández-Prieto b, c, e, * a Neuropsychophysiology Lab, CIPsi, Department of Basic Psychology, School of Psychology, University of Minho, Braga, Portugal b Centro de Investigación Biomédica en Red de Enfermedades Raras (CIBERER), Instituto de Salud Carlos III, Madrid, Spain c Grupo de Medicina Xenómica, Universidad de Santiago de Compostela, Santiago de Compostela, La Coruña, Spain d Department of Linguistics, University Autónoma of Madrid, Madrid, Spain e Genetic Molecular Unit, Galician Public Foundation of Genomic Medicine, University of Santiago de Compostela, Spain article info Article history: Received 29 July 2011 Accepted 7 April 2012 Available online 19 April 2012 Keywords: Smith-Magenis syndrome Cognitive profile Neurodevelopment abstract Smith-Magenis Syndrome (SMS) is a genetic neurodevelopmental disorder caused by a microdeletion on chromosome 17p11.2. This syndrome is characterized by a distinctive profile of physical, medical and neuropsychological characteristics. The latter include general mental disability, with the majority of individuals falling within the mild to moderate range. This study reports a detailed cognitive assessment of children and adults with SMS with the use of the Wechsler intelligence scales at three distinct levels of analysis: full scale IQ, factorial indices, and subtests. Child and adult samples were each compared to samples of age and gender-matched typically developing individuals. To our knowledge, this is the first study to systematically analyse the cognitive profile of individuals with SMS in Southern Europe. The present study confirmed mental disability, particularly within the moderate category, as a consistent feature of children and adults with SMS. Furthermore, both child and adult samples evidenced significant impairments in all four indices when compared with their typically developing counterparts. A specific pattern of strengths and weaknesses was discernible for both samples, with Verbal Comprehension emerging as a relative strength, whereas Working Memory appeared as a relative weakness. Finally, with the exception of two subtests in the perceptual domain, we found no evidence for a general cognitive decline with age. Ó 2012 Elsevier Masson SAS. All rights reserved. 1. Introduction Smith-Magenis Syndrome (SMS) [1] is a rare neuro- developmental disorder caused by a microdeletion on chromosome 17p11.2 which is believed to havean incidence of approximately 1 to 25000 live births [2]. Individuals with SMS display an unusual phenotype, which includes a distinctive profile of physical, medical and neuropsychological characteristics. One of the most salient aspects of their physical appearance regards the craniofacial phenotype: flattened mid-face, brachycephaly, depressed nasal bridge, down-turned mouth, prominent cheeks and jaw, syn- ophrys, as well as a relative prognathism that increases with age [3,4]. Individuals with SMS also commonly display short stature, short fingers and toes, tooth abnormalities, and hoarse voice [5,6]. In what concerns their medical profile, they tend to present hearing and eye problems, hypercholesterolemia, hypertriglyceridemia, thyroid function abnormalities, poor motor coordination and low muscle tone [7], as well as an inverted circadian rhythm of mela- tonin, which is thought to cause sleep disturbances [2,8,9]. Furthermore, individuals with this syndrome display distinct behavioural patterns, which may include hyperactivity, impulsivity, attention seeking, attentional problems, sudden mood swings, explosive outbursts, prolonged tantrums, aggressiveness, and self- injury behaviours [2,10] which can persist into adulthood [11]. However, they may also show positive behavioural features such as endearing and appealing personalities, eagerness to please and a good sense of humour [10,12e14] with communicative and sociability intentions relatively preserved [15]. Despite the very limited research available, general mental disability is believed to be characteristic of SMS, with the majority of individuals falling within the mild to moderate range [2,4,16,17]. A study conducted in England with a relatively large sample of children and adults with SMS yielded some of the most compre- hensive results on cognitive abilities in this syndrome to date [17]. * Corresponding author. Unidade de Medicina Molecular e FPGMX, Hospital Clínico Universitario Edifício de consultas, Planta e 2 Choupana, s/n 15706 Santiago de compostela, Spain. Tel.: þ34 981 951491; fax: þ34 981 951473. E-mail address: montse.fernandez.prieto@usc.es (M. Fernández-Prieto). 1 Share equal first authorship. Contents lists available at SciVerse ScienceDirect European Journal of Medical Genetics journal homepage: http://www.elsevier.com/locate/ejmg 1769-7212/$ e see front matter Ó 2012 Elsevier Masson SAS. All rights reserved. doi:10.1016/j.ejmg.2012.04.001 European Journal of Medical Genetics 55 (2012) 394e399