Aplasia cutis congenita (also known as "Cutis aplasia," "Congenital absence of skin," and "Congenital scars") is the most common congenital cicatricial alopecia, and is a congenital focal absence of epidermis with or without evidence of other layers of the skin.
It can be associated with Johanson-Blizzard syndrome, Adams-Oliver syndrome, trisomy 13, and Wolf-Hirschhorn syndrome. It is also seen with exposure to Methimazole and/or Carbimazole in utero. This dermatological manifestation has been linked to Peptidase D haploinsufficiency and a deletion in Chromosome 19.