Micronucleus Assay: An Early Diagnostic Tool to Assess Genotoxic Changes in Patients with Tobacco Use, Oral Leukoplakia and Oral Submucous Fibrosis.

Abstract

Micronuclei (MNi) are acentric chromatid or chromosome fragments produced via genetic damage through genotoxic agents contained in tobacco and betel nut. Evidently, the various Oral Potentially Malignant Disorders (OPMDs) like oral lichen Planus, oral leukoplakia and Oral Submucous Fibrosis (OSMF) demonstrate MNi, as a substantiation of genetic damage. As these changes can be easily appreciated in oral exfoliated cells, an exfoliated cell based MNi assay might be utilized as handy and non invasive biomonitoring tool for gauging the genetic damage and hence the propensity for malignant transformation in OPMDs. To this end, MNi are definitely easier to evaluate when compared to chromosome aberrations. To compare the MNi frequency in normal mucosa, in individuals using various tobacco forms without oral leukoplakia, individuals using various tobacco forms with oral leukoplakia, and areca nut chewers with OSMF, using three different stains. Oral exfoliated cells from 50 cases of normal mucosa (Group I), 50 cases of tobacco chewing people without Oral Leukoplakia (Group II), 50 cases of people with Oral Leukoplakia (Group III) and 50 cases of areca nut chewers with OSMF (Group IV) were taken. MNi frequencies were compared in these groups using three different stains i.e., Papanicolaou (PAP) stain, May Grunwald Giemsa (MGG) stain and Feulgen stain. The data between cases (Group II, III and IV) and control groups (Group I) was analyzed by Kruskal-Wallis Test. The comparison between two independent groups was done by Mann-Whitney U test and interstain comparison between cases and control was done by Wilcoxon Signed Rank Test and the individual p-value was obtained. A significant increase in the count was observed during transition of normal mucosa to OPMDs. The best stain for detecting MNi was PAP stain followed by MGG stain and Feulgen stain. The higher mean MNi count for PAP stain and MGG stain could be attributed to nonspecific staining. Further study using a larger sample size on quantitative assessment of MNi count in various OPMDs is warranted.