Fig. 3. Formation of unstable inverted Alu pairs and proposed consequences to human genome stability. Alu retroposition may lead to an inverted Alu pair. Depending on homology and distance, IRs may initiate genome instability either in wild type or in mutants. Among the outcomes in addition to homologous recombination may be chromosomal aberrations and LOH events. During evolution, inverted Alu pairs that have a destabilizing effect would be excluded from the human genome.