The age at which babies cut their first tooth very much depends on the age at which their parents did. But what genes — or general genome-wide differences, for that matter — mediate variations in this trait? Demetris Pillas and his colleagues set out to address this question, and others, by searching for genetic markers that affect primary-tooth development during infancy (D. Pillas et al. PLoS Genet. 6, e1000856; 2010).

The authors investigated records from two groups of subjects: one consisting of more than 4,500 individuals from northern Finland born in the mid-1960s, and the other made up of more than 1,500 individuals living in Britain and born in the early 1990s. They then performed genome-wide association studies on DNA extracted from blood samples taken from these individuals, looking for the genetic markers called single nucleotide polymorphisms (SNPs) that affect normal tooth development.

SNPs in five genomic regions (loci) stood out as showing a strong association not just with a delay in the time of first-tooth eruption but also with fewer teeth at the age of one year. SNPs within another five loci also seemed to associate with these traits, albeit to a lesser extent. The SNPs in the five top-ranked loci are within or near genes that have been implicated in growth and organ development, if not directly in tooth development, suggesting that tooth development is not an isolated event but is related to other developmental processes.


The extra benefit offered by Pillas and colleagues' subject groups was that, as well as providing records of infancy, the individuals were followed into adulthood. Taking advantage of this resource, the authors investigated how their top ten SNPs correlated with dental complications later in life. One SNP, rs6504340, which is located in the HOXB cluster of development-regulating genes, showed a strong association with a requirement for orthodontic treatment by the age of 30.

The authors point out the need for similar studies in other population groups to further establish the associations of these SNPs with tooth development. Given the link with other developmental processes, such studies might unveil connections with certain diseases in later life.