PKS is tissue‐limited mosaicism due to tetrasomy 12p. Our cohort exhibits the typical phenotypes of PKS, including classic dysmorphic features, global developmental delay, epilepsy, hearing impairment, and strabismus. Here, we confirmed that aCGH on peripheral blood sample may be considered as a first‐tier method to use when the PKS is suspected especially at early age. Moreover, the use of aCGH on a blood sample might avoid the need for a skin biopsy. Finally, the characterization of unbalanced chromosomal aberration and marker chromosome is more efficient by aCGH, which provides high resolution.