Article Aug 3, 2017

Explainer: American scientists “edit” human embryos

A team of researchers in Oregon has made the first known attempt at creating genetically modified human embryos in the United States, according to MIT Technology Review. Previously, such experiments had only been conducted only a few times by scientists in China.

As the report notes, none of the embryos were allowed to develop for more than a few days—and there was never any intention of implanting them into a womb. The purpose of the experiment was to show that by using “germline engineering” biotechnology may one day be able to eradicate or correct genes that cause inherited disease.

Critics of such experiments, however, warn that the procedure may be used to create “designer babies” where parents can select and enhance children for such traits as height, looks, or intelligence.

What is germline editing?

Gene editing (or genome editing) is a form of genome engineering in which DNA is inserted, replaced, or removed from the genetic material of a cell using artificially engineered enzymes, or "molecular scissors." Germline editing is when this procedure is used on the genome of germline cells.

What is a human germline?

Our genes, the basic physical and functional unit of heredity, are passed on from generation to generation through our sex cells (i.e., ovum (egg) and sperm). These sex cells are part of the germline. The term germline can refer to these cells in an individual or to the lineage of cells spanning generations of individuals. The other cells in the body that are not part of the germline (and hence do not pass on traits to other generations of people) are called somatic cells.

How do scientists “edit” the human genome?

A common method of genome editing, and the process used by the both American and Chinese researchers, is the CRISPR/Cas9 system. The simplistic explanation is that the “molecular scissors” (Cas9, an RNA-guided DNA enzyme) cuts an enzyme on a specific spot of DNA in the nucleus of a cell. The cell then repairs the break using a piece of single-stranded DNA that has been injected into the cell by scientists.

The following video provides a more in-depth, technical explanation of how CRISPR and Cas9 edit genes.

Is gene editing immoral or unethical?

There are two main ethical concerns related to such experiments.

The first is that human beings (embryos) are being created for the sole purpose of being experimented. After the experiments, the humans are killed. This destruction of innocent human life is a direct violation of God’s moral law (Genesis 9:5-6).

The second ethical consideration for gene editing is the purpose for which is done—whether the reason is therapeutic or for enhancement—and the long-term impact on both individuals and on mankind. This is why the ethical issues differ for gene editing on somatic (non-reproductive) cells (which would affect only the individual being treated) and on germline (reproductive) cells (which could potentially impact not only the individual but their offspring and future generations of their descendants).

The concern for germline editing is that therapeutic treatments that are passed along to future generations may have unexpected and unintended consequences. In essence, we would be experimenting on future generations without their consent.

The other worry is that the procedure could eventually be adopted for non-therapeutic genetic enhancement, a form of eugenics. For example, the process could be used by wealthy people to create “designer children” whose genetic “improvements” (e.g., height, intelligence, longevity) would be passed along to future generations.

Is there an ethical consensus on germline editing?

Currently, most researchers and ethicists agree that genome editing of human somatic cells for therapeutic treatments is largely uncontroversial, while germline editing should be prohibited. The process is banned, however, in 15 of 22 nations in Europe, though it is has not officially been banned in the U.S.

One area of disagreement is between groups who think that all forms of germline editing should be disallowed and those who believe the process should be used for research purposes on non-viable germline cells.

Why is non-therapeutic genetic enhancement problematic?

From a Christian perspective, therapy implies fixing a malady that is a result of sin entering the world, such as curing diseases or restoring broken physical systems. Enhancement, in contrast, is attempting to make improvements of the body that are either not the result of sin or not necessarily caused by human brokenness. Distinguishing between therapy and enhancement is a perennially tricky issue for Christian ethicists. Additionally, not all therapy is beneficial and not all enhancements are sinful.

Using gene editing for enhancement, though, is troubling for several reasons. For example, using the process on ourselves implies that humans know how to “improve” on God’s general design for the human body. It also can imply that certain traits (such as height or a particular IQ) are so preferable that they should be purposefully engineered so that they can be distributed in a way that is outside the normal distribution range for the human species.

Other concerns include questions about the cultural and social impacts of having certain humans be engineered to have the “right” traits. Will the changes lead to unjust forms of inequality? Will those who do not possess the preferred traits be treated as inferior or sub-human? Will discrimination increase for those who are unable or unwilling to modify their children?

Ultimately, the reason we should oppose germline editing is because children (and future generations of children) are to be considered as gift from God (Psa. 127:3) and not as products that we can tinker with and modify to our preferences.