'I've seen science fiction films with a plot that makes more sense', says Adam Pearson, at the start of his very personal film about his own genetics, 'My Amazing Twin', showing on BBC Two's Horizon. Being a British television producer and actor, Adam is no stranger to the screen. He also has type 1 neurofibromatosis (NF), a genetic condition that causes tumours to grow along nerves – in Adam's case facial nerves. His genetically identical twin brother, Neil, has no tumours. This is a medical conundrum. How much do these twin brothers really have in common? And how far can modern medicine understand and treat their illnesses?
It quickly becomes clear that this is a conundrum that baffles even the experts who have written the paper on Adam and Neil. They interview one of the co-authors at Guys' and St Thomas' hospitals in London, Professor Ros Ferner. The science is well-described and comprehensible to the viewers, but Adam has heard it all before, and is left frustrated by the lack of answers as to his and his brother's differences.
Moving on to Manchester, geneticist Dr Sue Huson has a hypothesis as to why Adam's condition is so severe. Finally, hurrah for science! She thinks he has two separate NF mutations on each side of his face, at odds of 40,000 to one. Adam has his face biopsied to check, but Dr Huson is proven wrong. The truth revealed by the biopsy is even more unlikely, and goes back to the very early stages of embryonic development. Adam developed a spontaneous NF mutation at the fetal stage in the womb after he had split from his twin but before his face had stared to develop. The second NF mutation, on top of the one he and his brother already shared, caused the tumours.
NF1 affects 1 in 2500 people, but usually less severely than in Adam's case. Adam, an anti-bullying spokesperson, speaks briefly but poignantly about the bullying he experienced as a child with NF. However, Adam keeps the tone light and full of jokes. He enjoys his friendship – 'dare I say a bromance' – with his amazing facial surgeon Dr Simon Eccles. But Dr Eccles is clear that all surgery can do is 'firefighting' on the constantly growing facial tumours. During the course of the programme, Adam has his thirty-second operation. He also turns 31 years old.
By this point, over halfway through the programme, the viewer is so invested in Adam and Neil's personal journey that it comes as a shock to learn that one likely suspect in the genetic disease is a mutation-causing chemical called Agent Orange, used by the US during the Vietnam War. The lens on NF suddenly widens as Adam visits Vietnam and finds hospitals overwhelmed with NF patients like himself. The hospitals are inundated by demand for surgery, and do not have enough resources. The doctors dream of a pill that could stop or reduce NF tumours. Can Adam find such a pill?
Given the sepulchral tone of every featured doctor, surely there is no wonder pill, the viewer thinks, sadly watching the sun set over the Vietnamese landscape. Spoiler alert, pessimists! Adam finds a pill being trialled on NF in the US – but would enrolling be worth the side effects, such as retinal detachment? This illustrates the risks and trade-offs concerned with clinical trial participation, which often the public don't hear about in the media. However, one thing that was glaringly absent from this section was any discussion of the economics of the pill, and we never learn if the trial will be expanded to Vietnam.
Back to the UK, the brothers reunite. They finally have some answers about their unusual genetics, and more choices about the future thanks to the trial. As for the viewers, they have undoubtedly learned something too; about the amazing work of plastic surgeons, about genetics and blind chance, about war, about bullying and about hope. As a biologist, I found Horizon turned an academically exciting genetics question into a gripping, moving and very human story. My Amazing Twin offers a thought-provoking look at both the scientific and the personal side of genetic disease, and I'd recommend it to all.