What’s New on the CRISPR Front?

By Michael Jorrin, "Doc Gumshoe", April 5, 2021

Aside from the tiny minority of people who can actually say what each of those initials stand for, we can divide the populace into two groups – those who specifically know that CRISPR is a tool used in gene editing and those who know (or figure) that it’s a highly promising but exceedingly complex technique for addressing difficult-to-treat medical conditions or diseases. And of course there are those who conclude that CRISPR must be something that makes things more crispy, like putting soggy French fries in the oven.

We’ll get to spelling out the acronym a bit further on in this piece – and believe me, just spelling it out won’t make you understand the way it works. I will attempt a clear explanation, not only of the acronym, but of how CRISPR works in gene editing. But in the meantime, a bit of background on the larger subject of gene editing itself.

Gene manipulation in some form has been around for a long, long time – millennia, dating from those times when nobody had the foggiest notion of what a gene was, or how it was that some but not all of the characteristics of the parent were passed on to the offspring. The term “parent” as used here does not refer to a human Daddy or Mommy but to whichever being, animal or vegetable, that gave rise to offspring. When hunter-gatherers selected the largest fruit from trees, brought these prizes back to their huts for dinner, and threw the pits on the dung heap, they were unknowingly practicing genetic manipulation. From those seeds the next generation of fruit trees would grow, producing bigger fruit than their cousins in the woods. Tulip fanatics in Holland in the 17th century were doing genetic manipulation, as were breeders of prized hogs, as well as the agronomists who gave us such mixed-breed fruits as the pluot (a cross between a plum and an apricot) and perhaps the grapefruit (a cross between a sweet orange and a pomelo, which looks like a grapefruit but is quite a bit larger, and more sour). The grapefruit may have emerged accidentally, or it might have been a deliberate creation.

In any case, what the creators of those hybrids (and many, many more) were doing was taking genetic material from different “parents” and putting them together such that the offspring are genetically modified – essentially different from their parents. But they had no idea that all characteristic features of the animals and plants they were working with were encoded in genes, nor yet even of the existence of genes.

The concept of genes and genetics came into being in the early years of the 20th century, although as yet nobody knew what a gene actually was. Chromosomes had been identified as related to inherited characteristics, and had even been observed under the microscope at that time, but what the chromosomes actually were was still unknown. As the capacities of microscopes progressed, it became possible to get a closer look at chromosomes, which led to the discovery in 1953 by Francis Crick and James Watson of the configuration of the DNA molecule in the chromosome, i.e., the famous double helix. DNA in turn was found to be composed of a linking of four amino acids, termed “bases” (adenine, cytosine, guanine and thymine plus a phosphate group and a pentose sugar). The human genome consists of about 6.2 billion bases, paired and linked together in a very long twisting chain, which is wound around itself so as to take up minimum space. The genetic information is carried by these 3.1 billion base pairs, and the possibility of effecting changes to that genetic information, such as eliminating the genes that carried the information that would cause diseases or disabilities, was immediately the subject of research.

The information carried in the genome m