UNASSIGNED: Phenytoin-induced gingival overgrowth is an adverse drug reaction affecting few individuals, on phenytoin therapy for its antiepileptic effect. Analysis of genetic variation of CYP2C9*2 gene was done to identify the action of metabolic enzyme cytochrome P 450 on this drug. The main background of this publication is a quick review about one of the molecular techniques used to identify the single-nucleotide polymorphism (SNP) using polymerase chain reaction coupled with restriction fragment length polymorphism (PCR-RFLP).
UNASSIGNED: Deoxyribonucleic acid (DNA) was extracted from 5 ml of venous blood withdrawn from the individual, who had gingival overgrowth following phenytoin therapy. DNA was isolated, using the phenol-chloroform method. Isolated DNA was used for SNP analysis of CYP2C9*2 presentation. The basic procedure used for SNP analysis in our case was PCR-RFLP.
UNASSIGNED: Genetic variation of CYP2C9*2 in our case was homomutant.
UNASSIGNED: The etiology of phenytoin-induced gingival overgrowth is always an enigma, but it is now becoming clearer that a multifactorial role may be involved in the cause. One of the factors analyzed was polymorphism of CYP2C9*2 gene and it was found to be homomutant in our case. Adverse drug reaction can be minimized, by either reducing the drug dosage or drug substitution. However, larger scale genome-wide study has to be carried out to confirm one of the etiopathogenesis as mutation of the CYP2C9 gene, in phenytoin-induced gingival overgrowth.

Drug-induced gingival overgrowth (DIGO) secondary to chronic phenytoin intake for seizure control is a well-recognized phenomenon. Phenytoin-induced gingival overgrowth (PIGO) usually resolves gradually following cessation of phenytoin intake. It is usually seen throughout the dentate regions of the maxillary and mandibular dental arches, but more severely affect their anterior portions exposed to atmosphere. We report a rare case of PIGO predominantly involving hard palate and floor of oral cavity, which has not been reported in English literature till date.