Alternative Lengthening of Telomeres: Lessons to Be Learned from Telomeric DNA Double-Strand Break Repair

Genes (Basel). 2021 Oct 29;12(11):1734. doi: 10.3390/genes12111734.


The study of the molecular pathways underlying cancer has given us important insights into how breaks in our DNA are repaired and the dire consequences that can occur when these processes are perturbed. Extensive research over the past 20 years has shown that the key molecular event underpinning a subset of cancers involves the deregulated repair of DNA double-strand breaks (DSBs) at telomeres, which in turn leads to telomere lengthening and the potential for replicative immortality. Here we discuss, in-depth, recent major breakthroughs in our understanding of the mechanisms underpinning this pathway known as the alternative lengthening of telomeres (ALT). We explore how this gives us important insights into how DSB repair at telomeres is regulated, with relevance to the cell-cycle-dependent regulation of repair, repair of stalled replication forks and the spatial regulation of DSB repair.

Keywords: ATRX; alternative lengthening of telomeres; break-induced replication; double-strand break repair; telomeres.

Publication types

  • Research Support, Non-U.S. Gov't
  • Review

MeSH terms

  • Cell Cycle
  • DNA / metabolism
  • DNA Breaks, Double-Stranded*
  • DNA Repair*
  • DNA Replication*
  • Telomere / metabolism*
  • Telomere Homeostasis*


  • DNA