The Island of the Colorblind

John is a very vivid storyteller, and as he told me this story – a story not just of a scientific odyssey, but of his own most passionate hopes and disappointments – he seemed to relive it with almost unbearable intensity. He had enjoyed a cordial relationship with Kurland and Gajdusek, he thought, and a passionate one with Spencer – but when, in 1990, he gave up on the cycad hypothesis (as four years earlier he had given up on the mineral hypothesis), a sense of intense isolation gripped him; he felt he was out in the cold, seen as an apostate by them all. In the early 1990s, he toyed with a viral hypothesis (this was very much in his mind when we first met, in 1993). But as a primary physician, a general practitioner, living and working amidst the whole affected community in Umatac, he has been forced to think in terms of the entire families or clans with lytico-bodig under his care – no external cause alone, it seemed clear, could adequately account for such a pattern of distribution. Had a genetic theory been thrown out prematurely? Much had changed since Kurland and Mulder first considered, then rejected, this in the 1950s. The classic Mendelian patterns of inheritance had now been joined by concepts of complex inheritance involving the presence of multiple genetic abnormalities and their interactions with each other and with environmental factors. Further, it was now possible to directly examine the genetic material with molecular biology, using technologies and concepts not available to the early investigators.

Working with Verena Keck, an anthropologist, John started to collect pedigrees of every patient he had seen – pedigrees of unprecedented accuracy and detail, including medical histories going back fifty years. The more pedigrees he obtained, the more he became convinced that there had to be some genetic predisposition, or perhaps several predispositions – for it looked as though the lytico and the bodig had different patterns in different families. Sometimes one saw a family in whom the affected members had only the lytico, sometimes a family in which the clinical expression was always bodig, and sometimes, more rarely, a family with both. The similarity of the pathological pictures in lytico and bodig, he started to feel, might have been misleading them all; genealogically, they seemed to be two separate diseases.

Recently John has embarked on a new series of studies, collecting DNA samples from all of his patients and sending them out for genetic analysis. He has been very excited by preliminary results indicating the presence of a genetic marker in several cases of bodig – a marker which seems to be absent in lytico and normal controls. His immediate reaction has been one of exuberance: ‘I feel the excitement coming again, and it’s a feeling I have not had since ‘86, when I was captivated by Spencer’s hypothesis.’ But it is an exuberance tempered by considerable caution (‘I don’t quite know what it means’). The search for genetic markers is extraordinarily laborious and difficult – it took more than a decade of incessant work to find a marker for Huntington’s chorea – and John is not sure whether these preliminary results will be borne out. (And even if a clear genetic basis is established for lytico and for bodig, John feels, this will indicate no more than a vulnerability or disposition; he has never doubted that some external agent is also necessary.)

It is now a third of a century since he and his colleagues delineated progressive supranuclear palsy in the early 1960s and perceived it as a unique yet exemplary disease which might shed some light on neurodegenerative disease in general. The similarity of the clinical picture of lytico-bodig and postencephalitic parkinsonism to PSP continues to intrigue him. He had been struck from the start by the fact that supranuclear palsies could also be observed in some patients with lytico-bodig, and on occasion in those with post-encephalitic syndromes too (on a recent trip to New York, he was intrigued to meet one of my post-encephalitic patients who has had a supranuclear palsy for more than thirty years). But he is not yet sure how to interpret these affinities.