Fragile-X and Down's syndrome: are there syndrome-specific cognitive profiles at low IQ levels?

Individuals with either fragile-X syndrome or Down's syndrome with IQ scores less than 40 were assessed on the Down Syndrome Mental Status Exam. The results of the testing were examined for syndrome-specific cognitive profiles. No evidence for syndrome-specific cognitive profiles were found. These same individuals were then classified as high or low IQ, and each group was examined for IQ-level-specific profiles. Unique IQ level cognitive profiles were found. Classifying the individuals with regard to aetiology obscured IQ-level-specific strengths and weaknesses. Researchers and developers of curricula are cautioned against generalizing cognitive profiles to all IQ levels of a specific genetic syndrome.