Book Description

Facial and dental features are of considerable importance in biomedicine and forensics. Facial appearance has a strong genetic component and could have evolved to facilitate individual recognition. Teeth are the hardest and well-preserved parts of the body and they have been used to establish biological relatedness among past and current human populations and to identify individuals. Although genes have been identified for various facial and dental phenotypes, the genetic basis of normal variation for both traits are still poorly understood. I performed Genome Wide Association Studies (GWAS) using ~700,000 genome-wide markers from ~6,000 Latin American individuals (CANDELA cohort). Ordinal and quantitative facial traits were assessed in individual photographs. Single Nucleotide Polymorphisms (SNPs) situated in four gene regions showed associations with three ordinal and quantitative traits related to nose morphology. Quantitative analyses, in addition, detected an association of SNPs in the Ectodysplasin A receptor (EDAR) gene with chin protrusion. Subsequently, statistical and experimental follow-up analysis were performed to endorse the discovered significant associations. Consistently, Edar mouse mutants were characterized to observe alterations of mandible length. Subsequently, I conducted GWAS for dental traits using the same markers from a subgroup of ~500 volunteers from the same cohort. Eighty-six traits were scored using the Arizona State University Dental Anthropology System (ASUDAS) scale. In addition, inciso-cervical, mesiodistal and bucco-lingual distances were measured on the incisors, canines and premolars in the same photos. Eleven of the categorical traits examined showed genome-wide significant association with SNPs in at least one genomic region and seven measurements showed genome-wide significant association with SNPs in four genomic regions. Ten of the genomic regions detected have been associated for other dental GWAS.