trinucleotide repeat expansion

Full Definition

Trinucleotide repeat expansion refers to the pathological increase in the number of three-nucleotide DNA sequences, which can cause various genetic disorders such as Huntington's disease, fragile X syndrome, and myotonic dystrophy. These expansions often exhibit anticipation, where successive generations show earlier onset and increased severity. The instability of these repeats during meiosis makes genetic counseling complex, as the number of repeats can change between generations, particularly through maternal transmission in some disorders.

Usage

Usage note: Hyphenate when used as a compound adjective.

In Context

• "Trinucleotide repeat expansion testing confirmed the diagnosis of Huntington's disease." — Genetic test report
• "The patient's symptoms were consistent with a trinucleotide repeat expansion disorder." — Clinical assessment