The assessment and diagnosis of intellectual disability when development is atypical. A Norwegian population study of individuals with CHARGE syndrome.

For individuals with CHARGE, the effect of the atypicality seemed most apparent during early childhood, stabilizing and subsiding towards adulthood. The test results' interpretability was weakest for the preschoolers progressively increasing until peaking in adulthood, emphasizing the importance of delaying the assessment and diagnosis of intellectual disability. Because of several validity issues connected to the observation-based measure, complementary testing should precede clinical evaluations when possible in the diagnostics of individuals with CHARGE.