1581 Genetic Association Study of CASP1 and EARR During Orthodontia

Saturday, March 24, 2012: 9:45 a.m. - 11 a.m.
Presentation Type: Poster Session
J. DEMPSEY1, G. FALC√O-ALENCAR1, L.A. MORFORD2, J. MACRI3, and J.K. HARTSFIELD JR.1, 1Oral Health Science, University of Kentucky, Lexington, KY, 2Center for Oral Health Research, University of Kentucky, Lexington, KY, 3Orthodontics and Oral Facial Genetics, University of Indiana - Indianapolis, Indianapolis, IN
Objective: Genetic variation in the IL-1ß gene is associated with increased external-apical-root-resorption (EARR) in orthodontic patients. Caspase 1 (interleukin converting enzyme) is an upstream catalyst for the activation of IL-1ß in both monocytic and osteoclastic cells. This study investigates the potential association of two single nucleotide polymorphisms (SNPs) in CASP1, rs530537 and rs580253, with EARR of the maxillary-incisors in orthodontic patients. The null-hypothesis states that variation in CASP1 is not associated with EARR. The alternative-hypothesis states that variation in CASP1 is associated with EARR.

Method: DNA was isolated from the buccal swabs of 159 Caucasian orthodontic patients (22-affected, 143-control) with informed consent. Taqman®-based genotyping was utilized for the allelic discrimination of rs530537 and rs580253 on the Roche LightCycler480. Pre/post-treatment radiographs were analyzed qualitatively by three investigators for EARR of the maxillary-incisors. Subjects were considered to be “affected” when at least two-of-three investigators agreed that EARR was present on at least one of the subject's maxillary-incisors. Chi-square analyses were used to assess Hardy-Weinberg equilibrium in the unaffected, and the association of rs530537 and rs580253 CASP1 genotypes with EARR in the affected and unaffected groups, with significance at (p<0.05). All samples were genotyped for rs530537, a subset of 74 were genotyped for rs580253.

Result: All rs530537 and rs580253 genotypes of the unaffected were in Hardy-Weinberg equilibrium. Chi-square analysis yielded p=0.89 and p=0.14 respectively for rs530537 and rs580253.

Conclusion: While the null-hypothesis could not be rejected for rs530537, rs580253 and EARR, the data are suggestive that analysis of additional subjects could reveal a small effect of the rs580253 CASP1, which is a functional polymorphism, on EARR. If demonstrated, this would indicate that CASP1 (or a locus in linkage disequilibrium with it) plays a role in EARR during orthodontic treatment. Additional subjects are being analyzed along with analysis of rs580253 CASP1 genotypes.

This abstract is based on research that was funded entirely or partially by an outside source: Southern Association of Orthodontists

Keywords: Cytokine, Genetics, Orthodontics, Resorption and Root
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