In Ishibashi et al. [22], three gain CNVs including the ARX locus were described: a 438 Kb duplication (P1) including the full copy of ARX, detected in a male patient with mild ID, speech delay and hypotonia; a 377 Kb duplication (P3) including a full copy of POLA1 and ARX, found in a male patient with developmental delay, growth retardation, and delayed speech; and a 813 Kb duplication (DECIPHER 266096 DP3), detected in a male patient with hypotonia and microcephaly (Table 1). The gene discussed is ARX; the disease is microcephaly.