Sister chromatid exchanges in adult epileptic patients on phenytoin therapy.

Sister chromatid exchanges (SCE) were studied in lymphocyte cultures of 12 adult male epileptic patients on long-term monotherapy with phenytoin (PHT) and of matched controls. Significantly increased frequency of SCE was observed in the epileptic patients as a group and in almost all individuals, indicating a detectable chromosome damaging effect of PHT therapy on its human users.