Incontinentia pigmenti achromians (hypomelanosis of ITO, MIM 146150): further evidence of localization at Xp11.

We report on a girl with apparent hypomelanosis of Ito (ITO); cytogenetic studies disclosed the karyotype 46,X,t(X;10)(p11;q11)mat. We present further evidence that at least one of the genetic forms of ITO is located at Xp11; reviewing the clinical characteristics of patients with incontinentia pigmenti type 1 (IP1) and ITO with X-autosome translocations, we suggest that IP1 and ITO represent allelic forms or a contiguous gene syndrome. Thus, different genetic alterations in this region (Xp11) give rise to ITO or IP1 or borderline phenotypes. We also suggest that all patients with ITO, due to Xp11 mutation, have functional or genetic mosaicisms.