[Alterations in nails and teeth as a clue for genodermatoses].

BACKGROUND: There are about 10,000 monogenic diseases and around 30% demonstrate alterations in the skin and its appendages. As there are so many genetic different skin diseases, clear diagnosis is often very difficult. AIM: The goal of this review is to give the clinicians some key features on nails and teeth which might help to identify rare genodermatoses. DISCUSSION: In the daily work genodermatoses manifest more commonly as incomplete or oligosymptomatic syndromes than as complete symptom complexes. To diagnose a rare disorder in such situations, a knowledge of key features which are characteristic for a genodermatoses is essential, so that a diagnosis can be advanced and the underlying gene defect identified. Changes in nails and teeth sometimes may be useful as diagnostic key features. Both structures originate from ectoderm and therefore they often appear in combination in diseases with major ectodermal malformations. Enamel defects resembling the lines of Blaschko are highly suggestive for focal dermal hypoplasia, even if other important signs and symptoms are missing. Enamel defects combined with gingival fibromas are highly suggestive for tuberous sclerosis. On the other side, triangular lunulae with malformation and dystrophy of the nail plate suggests nail-patella syndrome.