Behavioral phenotype of individuals with Down syndrome

Abstract

Evidence is reviewed for a developmentally‐emerging behavioral phenotype in individuals with Down syndrome that includes significant delay in nonverbal cognitive development accompanied by additional, specific deficits in speech, language production, and auditory short‐term memory in infancy and childhood, but fewer adaptive behavior problems than individuals with other cognitive disabilities. Evidence of dementia emerges for up to half the individuals studied after age 50. Research issues affecting control group selection in establishing phenotypic characteristics are discussed, as well as the possible genetic mechanisms underlying variation in general cognitive delay, specific language impairment, and adult dementia. MRDD Research Reviews 2000;6:84‐95. Wiley‐Liss, Inc.

Studying Interactions, Reactions, and Perceptions: Can Genetic Disorders Serve as Behavioral Proxies?

“…• Children with Down syndrome show relative strengths in visual versus auditory short-term memory (Hodapp, Evans, & Gray, 1999;Pueschel, Gallagher, Zartler, & Pezzullo, 1986), weaknesses in expressive language and in grammar (Chapman & Hesketh, 2000;Miller, 1999), and personalities considered as sociable and upbeat by their parents (Hornby, 1995;Wishart & Johnston, 1990).…”

Increased dosage of DYRK1A and DSCR1 delays neuronal differentiation in neocortical progenitor cells

“…DS is characterized by neurological, skeletal, cardiovascular, and immunological defects (Hasle et al 2000;Roizen and Patterson 2003;Antonarakis et al 2004). In particular, mental retardation is the most common phenotype in DS (Chapman and Hesketh 2000). DS brains are microcephalic, and structural alterations such as hypoplasia of the forebrain and cerebellum were observed in prenatal and perinatal stages (Schmidt-Sidor et al 1990;Golden and Hyman 1994;Weitzdoerfer et al 2001).…”

The cognitive phenotype of Down syndrome: Insights from intracellular network analysis

“…The average IQ is approximately 50, but ranges over 40 points from severely impaired to low normal intelligence. 5,6 Cognitive dysfunction is manifested as deficits in specific tasks requiring a functional hippocampus, specific strengths and weaknesses in language skills, implicating regions of the prefrontal and temporal cortices and the cerebellum, and additional deficits suggesting impaired prefrontal cortex function. [7][8][9] Cognitive dysfunction in DS thus presents a specific constellation of features that distinguish it from other intellectual disabilities, such as Williams syndrome and Fragile X.…”