Česká Stomatologie a Praktické Zubní Lékařství (Mar 2015)

Molecular and Genetic Basis of Non-Syndromic Tooth Agenesis

  • L. Kramerová,
  • P. Krejčí,
  • E. Míšová,
  • A. Ševecová

DOI
https://doi.org/10.51479/cspzl.2015.002
Journal volume & issue
Vol. 115, no. 1
pp. 4 – 12

Abstract

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Background: Tooth agenesis represents the most common anomaly of dental development, which according to Online Mendelian Inheritance in Man (OMIM) database, affects approximately 20% of the population. Although the anomaly is so common, the ethiology is still undisclosed. In most cases the agenesis is caused by genetic disorder, only a few develop due to external factors. Some of the external factors are rubeolla, syphilis, vitamin D deficiency or nutritional damage during pregnancy and early childhood. Other harmful factors are radiation therapy in orofacial area in early stages of the development of the patient, harms the mother caused by radiation, chemical substances or drugs (e.g. thalidomide, cytostatics). Local factors include various types of injuries, tumors and osteomyelitis. Hypodontia can occur as an isolated condition (non-syndromic hypodontia) or can be associated with a systemic condition or syndrome (syndromic hypodontia). Despite the fact that, tooth agenesis is so common, little is known about the genetic defects responsible for this complex condition. To date, the genes associated with the non-syndromic form of tooth agenesis, listed in OMIM, are MSX1 (muscle segment homeobox gene 1), PAX9 (paired box gene 9), AXIN2 (axis inhibition protein 2), EDA (ectodysplasin A), WNT10A (Wingless-type MMTV integration site family, member 10A) and LTBP3 (latent transforming growth factor beta binding protein 3). Cases with selective tooth agenesis caused by mutation in genes EDARADD (EDAR-associated death domain), NEMO (nuclear factor-kappaB essential modulator), KRT17 (keratin 17) and TGFA (transforming growth factor-alfa), were also published. All these genes vary both in terms of number of identified mutations and in terms of number of documented patients. These mutations explain the formation of tooth agenesis in only a part of affected individuals. Most patients have no defects in these genes. To select other genes, that are responsible for non-syndromic forms of hypodontia, the identification of genes that cause syndroms with symptoms of hypodontia, seems as reasonable direction of further research.

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