Just briefly, I want to respond to some of the, I think, errors or misinterpretations of this amendment in Senator Steele-John’s statement and to some of the accusations made. Senator Steele-John said that this legislation gives us 10 or more years to evaluate the trial and research phase. The legislation does not do that. The government estimates in the explanatory memorandum that the research and trial phase may take 10 years, but there is nothing in the legislation which prescribes that the research and trial phase will last 10 or more years. It could be done in two or three. There is no limit at all placed on the number of years.
I also want to respond to Senator Steele-John’s statement that this was not based on science at all. I only briefly mentioned this in my original contribution, but I will just lay out here that in fact there is a statistical, scientific basis for the number of 20 trial participants that we have settled on in this amendment. As I mentioned before, the outcomes that are going to come from mitochondrial donation techniques are going to be different for different people, absolutely for sure. Almost all medical treatments have different effects on different people. It would normally be possible to express the effects in some kind of normal statistical distribution, in terms of their success or failure or other attributes. When something is uncertain or provides outcomes that do not deliver a definitive result, in scientific statistics the common rule, as I mentioned in my original contribution, is that, if your sample size is at least 30, you generally will have a sample size that accords with the overall population. It’s known as the central limit theorem, and the rule of thumb is that, once you get to about 30, your so called t-stat, which is what you get from a sample population, will start to converge on the limit of the z-stat which is what you get from the—almost always hypothetical—population distribution. So 30 is usually the figure used.
We didn’t choose 30, because we can see that in the UK, after almost eight years of work, they have only had eight participants go through, so, if 30 were chosen as a threshold, it might be a generation’s time before we go into that clinical phase. So, even though 30 would be the statistical, scientific number, we thought it would be more reasonable to choose a lower number: 20. Keep in mind that you’ve already had eight go through in the UK, without a single successful live birth, so an additional 12 on top of that number of participants seems a fairly reasonable request of the science in this regard. Yes, that will take a number of years, but in no way, as I said before, will that hold up the provision of these services, because the provision of the services can occur right now. Once the bill passes—if the bill passes—the provision of mitochondrial donation services can occur straightaway, not through the clinical practice process but through a trial process. So no-one will be denied or unnecessarily delayed in their provision of the services. Of course, while the trial is occurring, they’ll be subject to significant monitoring and oversight, which are the conditions that are placed in this bill. I do think it’s reasonable that 20—or at least something like 20—participants go through such a trial phase so we understand all of the different potential effects that might occur in different people with different genetic structures as best we can before going through to the clinical practice stage, where there is less oversight and less intense activity than would be associated with a trial phase.
