Hypodontia, the congenital absence of one or a few permanent teeth, is one
of the most frequent alterations of the human dentition, Although hypodonti
a does not represent a public health problem, it may cause both speech and
masticatory dysfunction and esthetic problems. A missense mutation in the h
omeodomain of MSX1 gene has been associated with hypodontia of second premo
lars and third molars in humans. However, another study excluded this gene
as causative locus for hypodontia of incisors and premolars, To further inv
estigate the role of the MSX1 gene in human hypodontia, we analyzed the hom
eobox region of the MSX1 gene in 20 individuals with different patterns of
familial or isolated hypodontia, The direct sequencing of PCR products did
not show any polymorphisms or mutations in the human MSX1 gene, Our results
indicate that inactivation of MSX1 gene in humans must have a highly selec
tive effect on dentition, and other genes must be involved in the cause of
hypodontia in humans. Am. J. Med. Genet. 92:346-349, 2000. (C) 2000 Wiiey-L
iss, Inc.