Tooth and nail syndrome is a rare disorder, first described in 1965, characterized by nails that are thin, small, and friable, and which may show koilonychia at birth. It was named after Dr. Carl J. Witkop Jr., who first described it between 1978 and 1982. It is an autosomal dominant type of ectodermal dysplasia. Its estimated incidence is 2 in 10,000.