Genetics of the Class III Malocclusion in US Caucasians

The Class III skeletal malocclusion has been shown to have a genetic component, and is sometimes familial. In its most severe forms, this phenotype can be socially and physically debilitating, and typically requires a combination of surgical and orthodontic correction. Unfortunately, however, not all Class III cases treated in the mixed dentition or adolescence result in a permanent correction. This may partially be due to a person’s inherent genetic predisposition to adequately respond to growth modification protocol(s), or due to continued or increased mandibular growth. To date, little is known regarding the actual genetic factors that contribute to Class III malocclusion formation, especially within Caucasian populations living in the United States. With this funded proposal, we will recruit 10 Class III patients with a family history of Class III, along with 4 to 5 additional biologically related family members, to generate a family-based cohort of US Caucasians for the purpose of studying Class III genetic factors by linkage analysis. We will require that at least one (or more) of the additional participating family member(s) also exhibit a Class III phenotype. Participation in the study will involve providing informed consent and HIPAA authorization, allowing access to family dental history information, and providing a sample of saliva. Genomic DNA will be isolated from the saliva to genotype 21 potential markers of Class III malocclusion. If not available in our Axium dental records, facial photographs will be taken on all study participants, and a Cephalometric radiograph will be taken of all adults For this study, a skeletal Class III case will be defined as having an ANB of