Among these, a frameshift mutation (219InsG) within the paired domain of PAX9 produces a protein product associated with a severe form of molar agenesis in a single family.
As BMP4 is essential for the development of teeth and also for many other organs, it would be of considerable interest to find a BMP4 mutation that is associated only with tooth agenesis.
As previously reported, Pbx1 homozygous mutant mice (Pbx1-/-) develop malformations and hypoplasia or aplasia of multiple organs, including the craniofacial skeleton, ear, branchial arches, heart, lungs, diaphragm, gut, kidneys, and gonads.
Based on our observed defects in DNA binding by the mutant protein, we propose a loss-of-function mechanism that contributes to haploinsufficiency of PAX9 in this family with posterior tooth agenesis.
Based on previous in vitro experiments on mutation disrupting function of Msx1 homeodomain, we assume that the heterozygous g.8177G>T nonsense mutation affects the amount and function of Msx1 protein and leads to tooth agenesis.
Because Msx1(R31P) appears to be inactive and does not affect the action of wild-type Msx1, we propose that the phenotype of affected individuals with selective tooth agenesis is due to haploinsufficiency.
Biallelic loss-of-function mutations of human FAM20A have been known to cause enamel-renal syndrome (ERS), featured by agenesis of dental enamel, nephrocalcinosis, and other orodental abnormalities, including gingival hyperplasia.
By direct sequencing of the PCR products of TITF2, we screened the genomic DNA from 46 patients with thyroid dysgenesis (five had agenesis, six had hypoplasia, 15 had ectopy, and 20 were undetermined).
By including WNT10A in the DNA diagnostics of isolated tooth agenesis, the yield of molecular testing in this condition was significantly increased from 15% to 71%.
Cleft-side MxI2agenesis in CLP subjects appears to be largely a genetically controlled anomaly associated with cleft development, rather than a collateral environmental consequence of the adjacent cleft defect, since increased hypodontia involving multiple missing teeth observed remote from a cleft clearly has a significant genetic basis.
Cleft-side MxI2 agenesis in CLP subjects appears to be largely a genetically controlled anomaly associated with cleft development, rather than a collateral environmental consequence of the adjacent cleft defect, since increased hypodontia involving multiple missing teeth observed remote from a cleft clearly has a significant genetic basis.
Cleft-side MxI2 agenesis in CLP subjects appears to be largely a genetically controlled anomaly associated with cleft development, rather than a collateral environmental consequence of the adjacent cleft defect, since increased hypodontia involving multiple missing teeth observed remote from a cleft clearly has a significant genetic basis.
Cleft-side MxI2 agenesis in CLP subjects appears to be largely a genetically controlled anomaly associated with cleft development, rather than a collateral environmental consequence of the adjacent cleft defect, since increased hypodontia involving multiple missing teeth observed remote from a cleft clearly has a significant genetic basis.
Cleidocranial dysplasia (CCD, MIM#119600), for which the responsible gene is RUNX2, is a genetic disorder characterized by hypoplasia or aplasia of the clavicles, patent fontanelles, and a short stature.
Considering the discrepancy between the high incidence rate of agenesis and the relatively small number of reported causative mutations in PAX9, MSX1 and AXIN2 genes, the genetic contribution to oligodontia probably is much more heterogeneous than expected so far.
Crossing IP<sub>3</sub>R-LacZ mice with mice hypomorphic for Tbx1 alleles revealed that PTA of Tbx1 mutants may result from agenesis or hypoplasia of the pulmonary trunk; thus, the left and right central to peripheral PAs connect directly to the dorsal side of the truncus arteriosus in these mutants.