ABSTRACT
There is probably no other condition that has been more frequently referred to when discussing the occurrence of cluttering than Down syndrome. Down syndrome (DS), resulting from trisomy 21, is a well-known condition. With an incidence of 1 in 600–700 births, it is the most frequently occurring chromosomal abnormality (Lambert & Rondal, 1979). The condition is characterized by some typical physical characteristics such as a short stature, a flat occiput, small and slanting palpebral fissures, epicanthic folds (skin folds of the upper eyelid covering the inner corner of the eye), a depressed nasal bridge, a small nose, and an overlarge tongue relative to the size of the mouth (Pueschel, 1988). The syndrome is also associated with behavioural characteristics, including the presence of speech and language problems (Rondal & Buckley, 2003).
