Tooth and nail syndrome (also known as hypodontia with nail dysgenesis, Witkop syndrome, or mucoepithelial dysplasia syndrome)[1][2][page needed] is a rare disorder, first described in 1965, characterized by nails that are thin, small, and friable, and which may show koilonychia at birth.

[2]: 521 [3] It was named after Dr. Carl J. Witkop Jr., who first described it between 1978 and 1982.

[1] It is an autosomal dominant type of ectodermal dysplasia.

[4] Its estimated incidence is 2 in 10,000.

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