Dear Dr. Stewart
Just found out about you and enjoyed Letters to a Young Mathematician.  You talked about symmetry being the repetition of identical units, and I realized that DNA was this and I wondered if symmetry had been applied to DNA. I never heard anyone talking about this.  Like flaws in a crystal perhaps some diseases can be identified by looking at DNA this way. Maybe our knowledge of crystals gives us insight here.
Computer instructions are the same but I assume this has already been done since computing came from math. Have you written about this?
​Thank you for your time reading this. If you could point me to where I could know more I would really appreciate it.​



​ Perroni