Challenging behavior: Behavioral phenotypes of some genetic syndromes

Abstract

Challenging behavior in individuals with mental retardation (MR) is relatively frequent, and represents a significant obstacle to adaptive skills. The frequency of specific forms and manifestations of challenging behavior can depend on a variety of personal and environmental factors. There are several prominent theoretical models regarding the etiology of challenging behavior and psychopathology in persons with MR: behavioral, developmental, socio-cultural and biological. The biological model emphasizes the physiological, biochemical and genetic factors as the potential source of challenging behavior. The progress in the field of genetics and neuroscience has opened the opportunity to study and discover the neurobiological basis of phenotypic characteristics. Genetic syndromes associated with MR can be followed by a specific set of problems and disorders which constitutes their behavioral phenotype. The aim of this paper was to present challenging behaviors that manifest in the most frequently studied syndromes: Down syndrome, Fragile X syndrome, Williams syndrome, Prader-Willi syndrome and Angelman syndrome. The concept of behavioral phenotype implies a higher probability of manifesting specific developmental characteristics and specific behaviors in individuals with a certain genetic syndrome. Although the specific set of (possible) problems and disorders is distinctive for the described genetic syndromes, the connection between genetics and behavior should be viewed through probabilistic dimension. The probabilistic concept takes into consideration the possibility of intra-syndrome variability in the occurrence, intensity and time onset of behavioral characteristics, at which the higher variability the lower is the specificity of the genetic syndrome. Identifying the specific pattern of behavior can be most important for the process of early diagnosis and prognosis. In addition, having knowledge about behavioral phenotype can be a landmark in the creation of targeted treatment strategies for individuals with a specific genetic syndrome.

Problemi ponašanja kod osoba s mentalnom retardacijom (MR) su relativno česti i značajna su prepreka njihovom adaptivnom funkcionisanju. Učestalost, specifični oblici i manifestacije problema ponašanja mogu zavisiti od niza ličnih i činilaca sredine. U razmatranju etiologije problema ponašanja i psihopatologije kod osoba sa MR preovladava nekoliko teorijskih modela: bihejvioralni, razvojni, sociokulturološki i biološki. Biološki model ističe fiziološke, biohemijske i genetske faktore kao moguće uzročnike problema ponašanja. Napretkom na polju genetike i neuronauka otvorila se mogućnost proučavanja i otkrivanja neurobioloških osnova fenotipskih karakteristika. Kod genetskih sindroma praćenih MR može da se ispolji određena grupa problema i poremećaja koji čine njihov bihejvioralni fenotip. Cilj ovog rada je prikaz problema ponašanja koji se ispoljavaju kod najčešće proučavanih genetskih sindroma: Daunovog (Down), Fragilnog iks (X), Vilijemsovog (Williams), Prader-Vilijevog (Prader-Willi) i Angelmanovog (Angelman) sindroma. Koncept bihejvioralnog fenotipa podrazumeva veću verovatnoću ispoljavanja specifičnih razvojnih odlika i određenog ponašanja kod osoba s konkretnim genetskim sindromom. Iako je za opisane genetske sindrome tipična određena grupa (mogućih) problema i poremećaja koji sačinjavaju njihov bihejvioralni profil, vezu između genetike i ponašanja uvek treba sagledavati kroz probabilističku dimenziju. Probabilistički koncept uzima u obzir mogućnost unutarsindromske varijabilnosti u nastanku, intenzitetu i vremenu pojave bihejvioralnih karakteristika, pri čemu je ta varijabilnost veća što je manja specifičnost genetskog sindroma. Prepoznavanje specifičnog obrasca ponašanja može biti veoma važno za proces ranog dijagnostikovanja i prognoze. Osim toga, poznavanje bihejvioralnog fenotipa može da bude putokaz za kreiranje ciljanih strategija lečenja osoba s određenim genetskim sindromom.