WS MoreOrLess: Kidney Donation

Summary

---

Podcast Summary: More or Less – Kidney Donation

Host: Ruth Alexander (BBC Radio 4)
Episode Date: November 1, 2014
Theme: Exploring the statistics and realities behind kidney donation compatibility, as well as the numbers involved in founding populations.

---

Episode Overview

In this episode of More or Less, host Ruth Alexander investigates two intriguing listener questions:

1. How many people are needed to start a new population without problematic inbreeding?
2. What are the real chances that one spouse can be a kidney donor match for another?

Both questions are explored with the help of subject matter experts, yielding surprising and optimistic insights into genetics, transplantation, and human health.

---

Section 1: Founding Populations and Genetic Viability

Timestamps: 00:19–04:56

Key Points and Insights

• The episode opens with a whimsical question from listener Ben Moody, aspiring James Bond villain, who asks how many men and women are needed to avoid inbreeding problems when founding a new population.
• Ruth seeks out evolutionary biologist Dr. Yan Wong for an expert answer.

Notable Discussion

• Inbreeding vs. Genetic Disorders:

  • Dr. Yan Wong clarifies, “It’s not that inbreeding creates genetic disorders. What it is is that inbreeding exposes genetic disorders that are already present in the population.” (01:35)
  • Over generations, inbreeding can actually reduce the prevalence of these disorders because the carriers are more likely to manifest and thus be selected against.

• Population Size Needed:

  • Ecological “50/500 rule”—50 individuals for short-term, and ideally 500 for long-term viability. But for founding, small numbers can suffice, as shown by animal and human precedents.
  • Animal case studies: Just a handful of deer (three females, one male) in Finland and one breeding pair of wild sheep on an island.
  • Human examples: Pitcairn Island (descendants from “six Polynesian women and 11 Caucasian men”) and Tristan da Cunha (“seven females and eight males”).
    • Dr. Wong summarizes: “Under 20 seems like a reasonable conclusion for founding a human population.” (03:30)

• Founder Effect:

  • Small founding numbers can mean specific problems get amplified, as happened with asthma on Tristan da Cunha, where about “23% for diagnosable asthma, but probably over 50% have mild or potential asthma.” (04:20)

• Playful Bond Villain Advice:

  • Dr. Wong quips, “As a James Bond villain...you could probably found a new colony just with yourself and some vials of sperm from different men.” (04:51)

Memorable Moment

• The expert tone remains scientific but playful, indulging the Bond-villain angle for educational effect.

---

Section 2: The Odds of Kidney Donation Compatibility

Timestamps: 05:29–08:44

Listener Question

• Kay Varden asks about her experience: She was surprised to learn she could be a live kidney donor for her husband, even though they are not blood relatives. She wants More or Less to investigate how common this compatibility is.

Expert Insights

• Interview with Professor Anthony Warrens

  • President of the British Transplantation Society.

• Technological Advances:

  • “We’re now doing a very large number of living donations exactly like this, partner to partner, and the outcome really is fantastic.” (06:23)
  • Key improvements include manipulation of the immune system and antibody removal that make more transplants possible than ever before.

• Two Main Compatibility Factors:

  1. Blood Group Compatibility:
     • Antibody removal has “made blood group incompatibility almost a non-issue for 75 to 80% of people.” (06:46)
  2. Tissue Typing:
     • Still a hurdle, but modern immunosuppressive drugs “make it possible in many cases.” The outcomes are “close to comparable to people who have got...tissue type matched kidneys.” (07:24)

• Statistics for Partner-to-Partner Donation:

  • Professor Warrens: “Assuming people are blood group compatible, the chances...of it being possible to do a transplant between two partners are 80% or more. And so it’s a very likely scenario to be successful.” (07:58)

• Impactful Statistic:

  • “A person who’s agreed to donate his organs after his death will generate on average an extra 56 years of added life in other people.” (08:29)
    • Ruth notes the statistic is validated and may now be even higher.

Memorable Moments

• Prof. Warrens’ optimism: The advances in medicine mean most partners, even unrelated, can successfully donate kidneys to each other.
• The revelation of the 56 years of extra life from a single deceased donor is a striking and hopeful takeaway.

---

Notable Quotes

• Dr. Yan Wong on inbreeding and founder populations:
  • “It’s not that inbreeding creates genetic disorders. What it is is that inbreeding exposes genetic disorders that are already present in the population.” (01:35)
  • “Under 20 seems like a reasonable conclusion for founding a human population.” (03:30)
• Professor Anthony Warrens on transplant success:
  • “With the drugs available to us, assuming people are blood group compatible, the chances...are 80% or more.” (07:58)
  • “A person who’s agreed to donate his organs after his death will generate on average an extra 56 years of added life in other people.” (08:29)

---

Key Takeaways and Summary

• Founding a new population:
  • You could start with as few as 15–20 people, but randomness (founder effect) matters more than sheer inbreeding.
• Kidney donation compatibility:
  • Due to medical advances, about 80% of couples can achieve a transplant—even without close genetic matches.
• Organ donation’s impact:
  • One donor can give an average of 56 years of extra life to recipients, making donation a major public good.

---

For More Information or Listener Questions:
Email: [e-mail]
Listen to more episodes: http://bbcworldservice.com/moreorless

---

Transcript

[A]

This is the short edition of More or Less first broadcast on the BBC World Service.

[B]

Thank you for downloading from the BBC. For details of our complete range of podcasts and our terms of use, go to bbcworldservice.com podcasts

[A]

hello, this is More or Less on the BBC World Service and I'm Ruth Alexander. With the deaths of the actors Geoffrey Holder and Richard Keel in recent weeks, the world has lost two of the great vill from the James Bond films. We considered them irreplaceable, but then we had this email from a loyal listener.

[C]

I'm embarking on a career as a James Bond baddie and I want to make sure everything is carefully planned. I'm under no illusions that Commander Bond will thwart my first efforts to take over the world, but I'm keen to become a recurring character. And that's where you come in. I intend to escape from Mr. Bond at the last minute and populate an island or other planet, depending on budget. However, I'm not clear how many men and how many women I'll need to take with me to ensure we don't have any issues with inbreeding in the population that might cause genetic disorders and the like. So my question is, how many people do you need to create a new race of people? If you're able to help out, I'd be happy to offer you a job as either a henchman or a victim, depending on your inclination. Thanks, Ben Moody. I know, I'm working on the name.

[A]

So who should we get to answer that? Well, we thought an evolutionary biologist. We know, his name is Yan, Yan Wong.

[D]

Well, it's not that inbreeding creates genetic disorders. What it is is that inbreeding exposes genetic disorders that are already present in the population. And in fact, if you do inbreeding because it exposes it, that actually reduces the amount overall in the population eventually. But as for the actual numbers, you might have thought that it was quite large, say in the hundreds, because people who are interested in interstellar intergalactic travel have done calculations and they come up with hundreds of people. And ecologists have this rule called the 5500 rule, which says that for short term viability of a population, you need about 50 individuals. In fact, that's the effective population size, so probably more like several hundred. And for long term maintenance you need about 500 individuals. So the real number of individuals is probably in the thousands. I think that's slightly misguided actually, because it's not the long term population size you need to worry about it's just the number of founders of your colony that you take with you on your little escape pod. There are examples from other animals where really quite small numbers of individuals have founded successful populations. There are deer in Finland, three females and one male. And there's even a single breeding pair of wild sheep that were introduced, introduced from a Paris zoo to Oat island in the Kirligan Archipelago. In terms of humans, there are two examples that people often come up with, and that's Pitcairn island, which famously was founded by people from the Mutiny on the Bounty. The breeding population there now springs from six Polynesian women and 11 Caucasian men. Nine of those were from the Bounty and two arrived later. And if you look at the other example, Tristan da Cunha, it seems that you can trace everyone back to seven females and eight males. These aren't perfect experiments, because there probably were the occasional people visiting and immigrating, but under 20 seems like a reasonable conclusion for founding a human population. The problems from a genetic point of view aren't really inbreeding. They're more to do with just having a small population size and you get a thing called the founder effect, which means that if you have very few individuals, it might just be that you're dealt a bad hand at the start. For example, on Tristan de Cunha, there's a very high asthma rate. Two or possibly three of the original 15 founders happen to have relatively severe asthma, and now the population is sort of dominated by this asthma problem. A second problem is if you keep the population small for long periods of time, it's like repeatedly sampling. And so now. Now the asthma rate on Tristan de Kuna is 23% for diagnosable asthma, but probably over 50% of people have mild or potential asthma. But, you know, given the animals colonizing islands with just one breeding pair as a James Bond villain, especially if you're a female and young, then you could probably found a new colony just with yourself and some vials of sperm from different men.

[A]

Yan Wong there, helping the next generation of Bond villains. You're listening to More or Less on the BBC World Service. I'm Ruth Alexander. As regular listeners of More or Less will know, our programme always encourages loyal listeners to email in to query numbers that they've heard and want investigating. But some requests and ideas, we ignore the ones from our editor, which is why we almost overlooked one recently. But then we realise it wasn't from Richard the editor. It was from his mum, Kay Varden, a particularly loyal listener with an interesting question.

[E]

My Husband had problems with his kidneys and they gradually got worse and in the end they put him onto the pre dialysis clinic and said he had end stage kidney failure and if he didn't have a transplant he would need to go on dialysis. They talked about all the different options about kidney transplants, and I hadn't realized that there was any chance that you could do a live transplant if you weren't actually blood relative. But they said, oh yes, they would do tests and see if I might be a match. And so then I had various tests and we were rather surprised and very pleased to find that I was a suitable match. I want more or less to find out what are the chances of two people like myself and my husband being compatible.

[A]

So should Kay be surprised? Well, that's a question we asked Professor Anthony Warrens, president of the British Transplantation Society.

[F]

But she shouldn't be surprised because we're now doing a very large number of living donations exactly like this, partner to partner, and the outcome really is fantastic. Now, that's because we've learned to do some manipulation of the immune system that makes it possible to do transplants that frankly just wouldn't have worked 15 years ago.

[A]

There are two big things kidney transplant surgeons think about.

[F]

Number one is blood group compatibility. Now, that used to be an absolute barrier. If people were incompatible, then it just wasn't possible to do a transplant between them. But we're now able to remove the antibodies that we've got in our blood to prevent the damage to somebody whose kidney blood group is incompatible. Now, the outcome of having removed these antibodies is pretty close to the same as if there was no incompatibility of blood group. It does work for 75 to 80% of people who are blood group incompatible. If we can remove the antibodies. The second thing is what we call tissue typing. The details don't matter, but this is a higher hurdle to clear. But we've learned with the right immune suppressive drugs that we've got now available in many cases, we can suppress much of the immune response. The outcome is again, close to not the same, but close to comparable to people who have got, well, tissue type matched kidneys.

[A]

Well, three cheers for improvements in technology and clinical practice. Rather than asking ourselves what are the chances of a match, then the pertinent question to ask now is what are the chances of a successful transplant? Whether or not there's a good match,

[F]

Two partners are not going to be genetically related to each other, so you might predict that it's unlikely that they would have a tissue type in common, and that's largely true. But nonetheless, with the drugs available to us, assuming people are blood group compatible, the chances in my experience of it being possible to do a transplant between two partners are 80% or more. And so it's a very likely scenario to be successful.

[A]

But perhaps this is the standout statistic you'll take away from this week's program.

[F]

So if you consider transplantation of all organs, a person who's agreed to donate his organs after his death will generate on average an extra 56 years of added life in other people. That is a very major contribution.

[A]

And in case you're thinking that sounds like just the sort of statistic we should check, we have done published almost 10 years ago, so maybe it's even more now. Thanks to Professor Anthony Warrens, president of the British Transplantation Society. Well, that's all we've got time for this week, but if you have any numbers you're suspicious about or you just want help in building an evil empire, please do email us at more or lessbc.co.uk. you can also listen to other editions of More or Less at our website, bbcworldservice.com More or less

[B]

there are dozens of different podcasts now available from the BBC, including news, documentaries, science, business, arts and sports. The details of them all go to bbcworldservice.com podcasts.