Dr Hannah Brown

Researcher at the Robinson Research Institute, School of Medicine at the University of Adelaide, and the ARC Centre of Excellent for Nanoscale Biophotonics

最近、中国の研究グループはヒト胚をゲノム編集したと報告し関心を集めました。今回の超小型豚の作出にも同様の技術が使われています。今回のような成果は、ゲノム編集技術が、ハンチントン病、パーキンソン病、嚢胞性線維症などの遺伝子疾患を治療しうることを示しており、その意味では評価できます。ただし、超小型豚へのゲノム編集効果が豚の一生を通じて発揮されるのか、豚の健康が維持されるのかといったことは不明です。研究チームは、ゲノム編集技術を用いることで、飼い主が超小型豚の色や柄も指定できるとしていますが、「デザイナーズ・ペット」とでもいうべき動物の是非について倫理的な問題が出てくる可能性があります。

原文

“Genome editing tools have created excitement over the last few years for scientists in many fields, offering a way to cheaply, and easily alter the genetic make-up of individuals.  Recently, this technology generated a great deal of excitement when a research group reported they had genetically altered a human embryo.  Now, another Chinese research group have described a similar technology, which they have used to generate miniature pigs.

The technology, known as TALENs (Transcription activator-like effector nuclease), acts like a GPS-guided pair of molecular scissors, honing to a specific region of the DNA and cutting and altering the DNA backbone.  Technologies such as these (and including CRISPR) allow researchers to remove and replace faulty pieces of DNA (or genes), perhaps replacing the disease-causing DNA or information, with healthy information. These tools are routinely being used for scientific research purposes, but the number of live animals generated from the use of these technologies remains limited.

This is an exciting step forward in a research field where these technologies promise the possibility of curing genetic diseases caused by faulty DNA (including diseases like Huntington’s, Parkinson’s and Cystic Fibrosis). These technologies have been used heavily cells in culture, and in mice, but it is exciting to see live, large animals produced, and these miniature pigs appear to be a very useful research tool so far. 

Concerning, however, is that while it appears that they were able to generate a smaller pig (making research cheaper and easier), the effects that these genetic changes may have on the life of an animal that lives for many years is not yet established.  Whether the pigs will live a long healthy life remains to be seen.  These technologies are likely to also raise ethical questions about the necessity for designer-pets, with their creators suggesting they will be able to make pigs to order, with the owners being able to choose colours and patterns.”

Dr. Willard Eyestone

Research Associate Professor, Reproductive Biology / Biotechnology, Virginia Tech

今回の豚が極小サイズであることから私がまず思ったのは、長期にわたる研究で使いやすく便利な動物モデルになるだろうなということです。ただし、サイズを小さくするためのゲノム編集の影響が限局的で、他の遺伝子機能が普通の豚と変わらないことが前提になります。仮にサイズ以外のすべての点で一般の豚と変わらないとしても、技術的には食用の遺伝子改変動物と同等に扱われるべきで、米国食品医薬品局（ＦＤＡ）による遺伝子改変規制の範疇にあるといえます。ＦＤＡはゲノム編集の影響を慎重に検討し、この超小型豚をペットとしてどう扱うべきか決めることになるでしょう。

一方で、ペットにゲノム編集を施し、大きさや形、色などを変更してもよいものかどうかは公の場で討論されるべきです。現在のペットは無理な交配を重ねたことによる健康への悪影響が問題となっていますが、ペットと飼い主の両者の健康に資する場合には、ゲノム編集も一つの手段になると思います。

原文

"My first reaction to learning about these 'micropigs' was how useful they could be as a research model, especially for long-term studies, during which even currently available 'minipigs' grow to substantial size (which of course is why they were made in the first place).  Of course, their utility for research will depend on whether they are otherwise normal like a regular pig and unaffected by the edited gene other than their diminutive size.  That said, the gene editing technique used to generate the micropig is designed to introduce extremely precise, targeted changes to the genome that have similarly precise and targeted effects on phenotype, in this case adult size, and it is very likely that size will be the only trait affected by this particular 'edit'.

"Even if the micropig proves normal in every other way but size, it’s still a pig and technically a food animal, and the FDA at least reserves the right to regulate any genetic modification introduced into food animals.  However, traditional FDA-regulated GMO’s generally contain larger segments of DNA added to the genome.  In sharp contrast, the micropig was made by removing just a few, highly targeted letters of DNA from the genome.  The FDA should be grappling with this major difference right now as to how it will affect regulatory policy, and whether gene edited organisms should be regulated in the same way as more traditional GMOs.  I’m sure that at this stage the FDA will want to take the matter of marketing micropigs as pets under consideration.

"If the micropig is carefully evaluated and found to be equal in health compared to a normal pig and differs only in terms of size, then would be little scientific reason to block it from being offered as a pet.  The ethics of whether the use of gene editing for altering traits in pets should be the subject of public debate.  We must bear in mind that we have been altering the genetic make-up of pet animals for millennia, using the comparatively imprecise method of selective breeding, which sometimes results in less than healthy traits for the animal.  Gene editing offers a much more precise and potentially humane method to achieve traits that are both useful and desirable for people and healthy for the animal. So in principal, gene editing should offer a far more predictable and humane alternative to selective breeding for all domestic animals, including pets."