Somatic vs Germline Interventions and Ethics

The basic difference

MedlinePlus Genetics explains that most genome editing changes are limited to somatic cells, which are cells other than egg and sperm cells. These changes are isolated to certain tissues and are not passed from one generation to the next. [1] Changes made to genes in egg or sperm cells, or to an embryo, could be passed to future generations. [1]

An example of a somatic approach is a product approved by the FDA in which a patient's own blood stem cells are edited outside the body and returned to the same patient. [2] See gene editing and CRISPR explained and gene therapy vs gene editing.

Why germline editing is treated differently

MedlinePlus Genetics lists the concerns: germline therapy might affect the development of a fetus in unexpected ways or have long-term side effects that are not yet known, and the people affected are not yet born and cannot choose whether to have the treatment. [3] It also raises the question of whether such tools could be used to enhance normal traits such as height or intelligence. [1]

An international commission of the U.S. National Academy of Medicine, the U.S. National Academy of Sciences and the U.K.'s Royal Society concluded that edited human embryos should not be used to create a pregnancy until it is established that precise genomic changes can be made reliably and without introducing undesired changes, criteria it said have not yet been met. [4] It called for extensive national and international dialogue before any country decides whether to permit clinical use. [4]

The 2018 case

In November 2018, Chinese researcher He Jiankui announced that he had used CRISPR on human embryos to edit the genes of twin girls, intending to protect them against HIV. [5] Many scientists expressed concern about possible unintended side effects that could be passed to future generations. [5] In December 2019 a court in Shenzhen sentenced him to three years in prison and fined him about $430,000 for illegal medical practice, and it indicated that three genetically edited babies had been born. [5] This account is from a news report (NPR, December 2019), not from a scientific paper or a court document, and the sentence was reported at that time. This page did not verify later events.

The case is an example of research that went around oversight, not of an accepted treatment.

What WHO recommends in outline

The WHO published a governance framework and a set of recommendations from an expert committee that examined the scientific, ethical, social and legal challenges of human genome editing, including somatic, germline and heritable editing. [7] The recommendations cover nine areas, including human genome editing registries, international research and medical travel, and illegal, unregistered, unethical or unsafe research and other activities. [8] The documents are guidance for governance, and they do not by themselves approve any use.

How to think about claims

• "Gene editing" is not one thing. Check whether a claim is about body cells in one patient or about embryos or reproductive cells.
• Heritable editing is not an approved treatment in the sources read here. The commission said criteria for safe clinical use had not been met. [4]
• Offers of embryo editing or "designer baby" services should be treated as red flags. The WHO list of governance areas includes illegal, unregistered, unethical or unsafe activities and medical travel. [8]

Related: off-target effects, durability and long-term monitoring, genetic privacy and incidental findings and gene-therapy access and cost.