A genetic disorder characterized by the absence of several teeth at birth and abnormalities of the nails. The disorder is also known as hypodontia and nail dysgenesis or Witkop syndrome (TNS). It was first described by Dr. Carl Witkop in 1965.
The tooth and nail defects in the syndrome are highly variable. The number and type of congenitally missing permanent and/or primary teeth vary. The nails are thin, slow-growing, brittle and spoon-shaped (koilonychia). Toenails are usually more severely affected than the fingernails. In rare cases, the nails spontaneously separate from the nail beds or are absent at birth.
About 1 in 1,000 people has TNS. It is inherited as an autosomal dominant trait capable of affecting males and females and multiple generations.
The gene responsible for TNS was identified in 2001 and is termed MSX1. A nonsense mutation in this gene in TNS appears to encode a protein that is completely nonfunctional. Another nonsense mutation in MSX1 has been associated with oral clefting in addition to tooth agenesis (absence of teeth).
- Primary teeth
The first teeth which are shed and replaced by permanent teeth. The first primary tooth comes in at about 6 months of age and the 20th and last primary tooth erupts at around 2 1/2 years of age. The primary teeth are replaced beginning usually at about age 6. Also called baby teeth, milk teeth, […]
- Tooth erosion
The gradual loss of the normally hard surface of the tooth due to chemical, not bacterial, processes.
- Tooth numbering
(1) is the patient’s upper right molar and follows around the upper arch to the upper left third molar (16), descending to the lower left third molar (17) and follows around the lower arch to the lower right third molar (32). The Universal/National System is used primarily in the United States whereas the International Standards […]
- Tooth root
The lower two-thirds of a tooth. The roots are normally buried in bone, and they serve to anchor the tooth in position. The roots are covered with a thin layer of bone, and they are inserted into sockets in the bone of the jaw.
- Tooth root sensitivities
Oversensitivity of exposed roots of teeth to cold, hot, and sour foods because those roots are no longer protected by healthy gum and bone. Chronic gum disease contributes to toothache due to root sensitivities. The roots are the lower 2/3 of the teeth that are normally buried in bone. The bacterial toxins dissolve the bone […]