Background: The skin is especially suitable for the study of mosaicism. In this review, the
various genetic mechanisms leading to mosaicism and the resulting cutaneous patterns are
considered. Observations: Mosaicism may produce different cutaneous patterns such as the
lines of Blaschko, the checkerboard pattern, the phylloid pattern, and a patchy pattern
without midline separation. A unique lateralization pattern is observed in the CHILD
syndrome. Two major genetic categories arefunctional mosaicsresulting from X inactivation …