Genetic background of nonsyndromic oligodontia: a systematic review and meta-analysis.

OBJECTIVES: The goal of this work was to identify all known gene mutations that have been associated with the development of nonsyndromic oligodontia.
METHODS: A systematic literature search was performed electronically in two databases (PubMed, Medpilot) supplemented by a hand search. Articles published up to March 2012 were considered. Search terms were combined as follows: oligodontia and genes, oligodontia and mutations, tooth agenesis and genes, and tooth agenesis and mutations. A meta-analysis of the data was conducted based on the Tooth Agenesis Code (TAC).
RESULTS: Seven genes are currently known to have a potential for causing nonsyndromic oligodontia. All these genes vary both in terms of number of identified mutations and in terms of number of documented patients: 33 mutations and 93 patients are on record for PAX9, 10 mutations and 51 patients for EDA, 12 mutations and 33 patients for MSX1, 6 mutations and 17 patients for AXIN2, and 1 mutation in 1 patient for EDARADD, NEMO, and KRT17 each. A total TAC score of 250 was found to have cutoff properties, as 100% of MSX1 and 80% of EDA patients exhibited TAC ≤ 250, whereas 96.9% of PAX9 and 90% of AXIN2 patients exhibited TAC >250. Furthermore, 94.3% of EDA patients but only 28.6% of MSX1 patients exhibited odd-numbered TAC scores in at least one quadrant, and 72.7% of PAX9 but none of the AXIN2 patients were found to show TAC scores of 112 in at least one quadrant.
CONCLUSION: In order of decreasing frequency, PAX9, EDA, MSX1, AXIN2, EDARADD, NEMO, and KRT17 are the seven genes currently known to have a potential for causing nonsyndromic oligodontia. TAC scores enabled us to identify an association between oligodontia phenotypes and genotypes in the patients covered by this meta-analysis.