anticipation
A genetic phenomenon where a condition becomes more severe or has earlier onset in successive generations of a family.
Full Definition
Genetic anticipation refers to the progressive worsening of a genetic condition through generations, typically involving earlier age of onset, increased severity, or both. This phenomenon is most commonly associated with trinucleotide repeat expansion disorders, where the number of DNA repeats increases when passed from parent to child, particularly through paternal transmission in some conditions. Understanding anticipation is crucial for reproductive genetics counseling as it affects recurrence risk estimates and family planning decisions.
Usage
Usage note: Often qualified as 'genetic anticipation' to distinguish from common usage of the word.
In Context
- "The family history showed clear anticipation, with each generation experiencing earlier onset of symptoms." — Clinical genetics consultation
- "Anticipation is characteristic of Huntington disease, with paternal transmission often leading to juvenile onset." — Medical textbook