The ZNF81 gene encodes a putative transcription factor with Krupple-type zinc finger binding motifs, but its specific biologic functions are yet to be determined. The ZNF81 gene is located at Xp11.23 and contains 4 coding exons. Missense mutations and a complex rearrangement disrupting the ZNF81 gene have been reported in patients with X-linked mental retardation (Kleefstra T et al. J Med Genet. 2004;41:394-399).