Rewriting Your Genome

Comments Off on Rewriting Your Genome
Rewriting Your Genome

The human genome is the equivalent of an enormous book in which the letters A, C, T, and G are written in endless combinations that determine—among other things—how tall or short you will be, what color eyes you will have, and whether or not you will develop a life-threatening disease.

But what if scientists could "read" that book, identify a "typo" in the letters that will cause you to suffer from a medical condition, and then "edit" that typo to fix it and prevent the disease from developing?

It sounds incredible, but that is precisely what several research teams are working on right now. So far, working on fruit flies, zebrafish, mice, rats, monkeys, and human cells, they have shown that it is possible to reverse serious health problems that are caused by single genetic mutations, such as hemophilia, liver disorders, and Huntington's disease.

The recent breakthroughs all center on the CRISPR-Cas system. CRISPRs, short for Clustered Regularly Interspaced Short Palindromic Repeats, are mechanisms that bacteria use to defend themselves from viral infection. CRISPRs were first discovered in 1987, but scientists only recently copied the approach to create a powerful genome-editing tool.

When it detects an invader such as a virus, the system responds by creating CRISPRs, which are small strands of RNA that match DNA sequences specific to a given invader. When those CRISPRs find a match, they unleash Cas9 proteins that cut the DNA.

The key to this process is the Cas9 complex, which includes the CRISPR "cutting" enzyme Cas9 and an RNA "guide" that leads the enzyme to its DNA target and tells it where to make its cut to eliminate the flawed sequence.

For example, MIT researchersrecently used the system tocure mice of a rare liver disorder caused by a single genetic mutation. The findings, described in Nature Biotechnology,1 offer the first evidence that the CRISPR gene-editing technique can reverse disease symptoms in living animals.

For this study, the researchers designed three guide RNA strands that target different DNA sequences near the mutation that causes type 1 tyrosinemia, in a gene that codes for an enzyme called FAH.

Patients with this disease, which affects about 1 in 100,000 people, cannot break down the amino acid tyrosine, which accumulates and can lead to liver failure. Current treatments include a low-protein diet and a drug called NTCB, which disrupts tyrosine production.

In experiments with adult mice carrying the mutated form of the FAH enzyme, the researchers delivered RNA guide strands along with the gene for Cas9 and a 199-nucleotide DNA template that includes the correct sequence of the mutated FAH gene...

To continue reading, become a paid subscriber for full access.
Already a Trends Magazine subscriber? Login for full access now.

Subscribe for as low as $195/year

  • Get 12 months of Trends that will impact your business and your life
  • Gain access to the entire Trends Research Library
  • Optional Trends monthly CDs in addition to your On-Line access
  • Receive our exclusive "Trends Investor Forecast 2015" as a free online gift
  • If you do not like what you see, you can cancel anytime and receive a 100% full refund