CRISPR-Cas9 is a precise method of gene editing. It can snip a gene out of the DNA sequence –say, a harmful mutation – then add a healthy gene to replace it. This new but exciting technique is being used in clinical trials to treat things like hereditary cancer. It could also be a godsend for certain genetic diseases, such as Huntington’s or Tay-Sachs disease, among others. Experimental studies with cancer and blindness are slated to reap benefits this year.