Most patients have been identified by array comparative genome hybridization technologies, since this technique has become the standard in the diagnostic work-up of patients with developmental delay. Other quantitative methods such as quantitative real-time PCR or MLPA can also be used for direct clinical testing or confirmation of array results.
The sizes of the reported duplications vary between 300 kb and 4.2 Mb, and are too small to be detected by classical chromosome analysis.