Definition: In genetics, anticipation refers to changes in a genetic disorder as it is passed from one generation to the next, such as symptoms appearing at earlier ages or becoming more severe. Anticipation most commonly occurs in disorders caused by the abnormal repetition of a sequence of three building blocks of DNA (nucleotides). When these repeats occur too many times, a gene may function abnormally, and as the number of repetitions accumulates, the severity of the disease increases.