Figure 6.

Hypothetical multi‐step mechanism forming the abnormal chromosome X structure. (a) Chromosome X bending. A telomeric end of chromosome X is flipped prior to DNA replication of chromosome X. (b and c) Template switching during DNA replication. A replication error occurred in a DNA replication fork at NC_000023.11 nt155,013,481 (F8 intron 1) followed by an intra‐chromosomal template switching into NC_000023.11 nt155,028,224 (FUNDC2) with two bases of microhomology. This strand switching could be explained by FoSTeS or MMBIR. (d and e) Template switching back and mutant allele formation. After synthesizing a duplicon strand, the abnormal strand switched back to the original strand via an int1h‐1 on the original strand and an int1h‐2 on the abnormal strand. The recombination machinery between the int1h‐1 and ‐2 could have occurred due to homologous recombination or FoSTeS/MMBIR