Why do frequent mutations to hypervariable region of DNA not cause harm to humans?​

If most mutations are due to DNA replication errors, then mutation rates are expected to be higher in males than in females, owing to the greater number of cell divisions per generation in the male germ-line.

during the process of dna replication, brdu can replace thymidine and incorporate into the newly synthesized dna, cell proliferation thus can be reflected in the extent of brdu incorporation.