A scientist recently announced he had manipulated the genes of twin girls before they were born so they would be less likely to ever get HIV infection. This announcement brought a lot of attention to gene research and gene manipulation, and to CRISPR, the instrument used by the scientist. Here is the background you need for you to get into the discussion.
What are Genes?
Genes are big molecules of DNA. They control cells and what cells do. Genes are in almost all human and other animal cells. Plant cells also have genes, but they have cell walls, vacuoles, and other differences. One-celled organisms, bacteria and archaea, have genes— one gene per bacterium or archaeon. (Viruses are bits of DNA or RNA with a protein coat. They do not have genes.)
Genes, the big molecules of DNA, are made up of smaller molecules called nucleotides. There are only a handful of different kinds of nucleotides, but piling them up in various ways can produce virtually unlimited sets of combinations.
Here’s the order, small to larger: nucleotide molecules make up DNA; DNA molecules make up a gene; a collection of genes make up a chromosome; and all the chromosomes as a package are the genome.
What is CRISPR (and is it spelled correctly?)
It’s an acronym for Clustered Regularly Interspaced Short Palindromic Repeats. These protein bits of virus material help cells create an antibody to a virus.
But today, CRISPR is often used as a shortcut word for CRISPR-CAS9, a substance used to manipulate cells to add or subtract gene components. Researchers generate artificial CRISPR protein bits to match the targeted DNA. CAS stands for Cellular Apoptosis Susceptibility, a characteristic that allows cells to cut off a function related to the CRISPER. This is the substance that ‘cuts out” the cell.
So, the components of the instrument used for gene manipulation are (1) the RNA in the CRISPR part which guides the other part, and (2) the CAS9, an enzyme that can dissolve or break molecular bonds like microscopic scissors. CAS9 can also break bonds that cripple a function, so it can activate some functions as well as block a function. Additionally, a DNA template can be added to CRISPR so new DNA can be inserted in place of the cut-out DNA.
How the Babies Genes Were Changed
The scientist, He Jiankui, said he “knocked out” or immobilized one gene, the CCR5 gene. That gene produces a receptor on white blood cells that (perhaps) catches HIV viruses; people without those receptors are less likely to get HIV if exposed.
Scientists Shudder But Potential Benefits Emerge
While conceivably gene manipulation in babies could modify human genes to produce a “super race,” scientists worry that such controversial work could draw negative emotions to gene science. Gene science has great potential to reduce human disease and suffering.
- STIM1, a gene on chromosome 11, appears to be involved in Alzheimer’s dementia; many people with Alzheimer’s dementia have a deficiency in STIM1. Perhaps gene manipulation, enhancing or adding STIM1, could reduce or even prevent Alzheimer’s dementia.
- Scientists in Spain are currently developing ways to control invasive breast cancer. ETS1 genes, also on chromosome 11, are involved in the spread of breast cancer. Knocking out that gene may reduce cancer spread, allowing it to be removed surgically.
- One gene, SCN9A, is an important link in feeling pain. Manipulation to block that gene could possibly reduce suffering from chronic pain.
Many other gene studies that could lead to break-through benefits are underway.