gentagelsesstabilitet

Gentagelsesstabilitet refers to the consistency with which a specific DNA repeat sequence is maintained across cellular replication cycles. It is most commonly discussed in the context of tandem repeats, such as microsatellites and minisatellites, which consist of short, consecutive nucleotide motifs. The stability of these repeats is influenced by DNA polymerase slippage during replication, the efficiency of DNA mismatch repair pathways, and the local chromatin environment.

During replication, DNA polymerase can temporarily disengage from a repeat tract and re‐anneal at a misaligned position, leading to insertion or deletion of repeat units. If the mismatch repair machinery fails to correct these errors, the repeat number changes, producing a new allele. In organisms with highly active mismatch repair, repeat length changes are rare, resulting in high gentagelsesstabilitet. In contrast, individuals or cell types with deficient repair enzymes exhibit increased repeat instability, which can accumulate over many generations.

Gentagelsesstabilitet is clinically significant because expansions of certain repeats are pathogenic, as seen in Huntington’s disease, myotonic dystrophy, and fragile X syndrome. In these disorders, instability of the affected repeat drives disease progression and determines age of onset. From an evolutionary perspective, repeat instability contributes to genomic diversity and can generate new regulatory elements or gene variants.

Measurement of gentagelsesstabilitet typically involves allele frequency analyses in pedigrees, single‑cell sequencing to track repeat number changes, or in vitro replication assays with reporter constructs. Statistical models that account for slippage rates and repair efficiency are employed to predict the likelihood of repeat number alteration over time. As genomic technologies improve, the ability to quantify gentagelsesstabilitet will enhance our understanding of disease mechanisms and evolutionary processes.