Anticipation (genetics)

Anticipation is a phenomenon observed in certain genetic disorders where the symptoms of the disorder become apparent at an earlier age with each succeeding generation. This phenomenon is also associated with an increase in the severity of the symptoms in each subsequent generation. Anticipation is most commonly observed in disorders that are caused by the expansion of trinucleotide repeat sequences.

Mechanism

The mechanism of anticipation is not fully understood, but it is believed to be due to the expansion of trinucleotide repeat sequences in the DNA. These sequences can become unstable and expand in size when they are passed from parent to child. This expansion can lead to an increase in the severity of the disorder and a decrease in the age of onset.

Disorders associated with anticipation

Several genetic disorders are associated with anticipation. These include:

• Huntington's disease
• Myotonic dystrophy
• Fragile X syndrome
• Friedreich's ataxia
• Spinocerebellar ataxia

In each of these disorders, the symptoms become more severe and appear at an earlier age in each subsequent generation.

Research

Research into anticipation is ongoing, with scientists seeking to understand the exact mechanisms behind this phenomenon. This research could lead to new treatments for the disorders associated with anticipation.

See also

• Genetic disorder
• Trinucleotide repeat disorder
• Genetic anticipation