<prompt> All of the following are true about incontinentia pigmenti, except:Ocular involvement is seen in almost 100 cases and is typically unilateralAvascularity of peripheral retinaPrimary skin abnormalityX-linked dominant  <response>: Ocular involvement is seen in about 20-35 percent of the cases of incontinentia pigmenti but not in 100 percent cases as mentioned in the option. Incontinentia pigmenti is a X-linked dominant primary skin disease that leads to avascularity of the retina. Ref: Rooks Textbook of Dermatology 7th Edition, Pages 39.20-3.22; The Retinal Atlas By Lawrence A. Yannuzzi, Page 38 