Cytochrome P450 2C9 gene polymorphism in phenytoin induced gingival enlargement: A case report
A 18-year-old male patient came to Department of Periodontics, Mahatma Gandhi Post Graduate Institute of Dental Sciences, Pondicherry, with a complain of swelling of upper and lower teeth gums for the past 10 months. Patient's medical history revealed that he had been on long-term phenytoin therapy (10 years) for primary generalized epilepsy at a daily dose of 300-mg/day. On intraoral clinical examination, there was generalized gingival enlargement involving marginal, attached, interdental papilla of upper and lower anterior teeth both labial and lingual/palatal aspects [Figures -] and on the buccal aspects of upper and lower premolars and first and second molars. The enlargement was pale pink in color, firm, resilient with minutely lobulated surface and no tendency to bleed on probing. There was also presence of supra and subgingival deposits. There were no any other significant dental findings. Based on these clinical findings a provisional diagnosis of Phenytoin induced gingival enlargement with superimposed inflammatory component was made.\nRoutine blood investigations were done which were found to be within normal limits. Gingival enlargement was due to phenytoin toxicity. This phenytoin toxicity prompted appropriate pharamacogenomics studies. Patient was informed verbally and written informed consent was obtained. 5 ml of venous blood was collected from the antecubital vein into ethylenediaminetetraacetic acid tubes. Plasma was separated by centrifugation and stored at −20°C until the assay. After separation of plasma, the cellular fraction was subjected to DNA extraction from leukocytes by the standard phenol: Chloroform procedure and genotyping of CYP2C9 was performed by a polymerase chain reaction-restriction fragment length polymorphism method. The CYP2C9* (Arg144 Cys) was detected using the forward and reverse primers 5´ TACAAATACAATGAAAATATCATG 3´ and 5´ CTAACAACCAGA CTCATAATG 3´, respectively and the genotype result was found to be homozygous CYP2C9*3*3.