Lethal legacy left by Columbus

Press, 12 October 1988, Page 20

Lethal legacy left by Columbus

ROBIN McKIE,

of the “Observer,” looks at

a disease inherited from early explorers to the Caribbean.

A unique international project has been launched to eradicate a genetic disease that has afflicted an entire region of Cuba. The disease is a form of ataxia, an inherited, neurological illness that slowly cripples victims. Scientists believe it was brought to the island by one of the crewmen who took part in Christopher Columbus’s expedition to America almost 500 years ago. Since then, this form of ataxia — known as Olivo-Ponto cerebellar ataxia — has affected increasing numbers of people in the area of Holguin, on the north side of Cuba. Today, in some parts, almost every family has someone with the disease. In the town of Holguin, capital of the region, for instance, it is common to see many victims with their characteristic clumsy, uncertain gait. It is one of the world’s largest communities of inherited disease victims. And by estimating ataxia’s current prevalence, and by calculating how long it has taken to reach that level, scientists deduce the disease arrived on Cuba about 500 years ago — at the same time as Christopher Columbus landed there. “Given that Columbus landed at Holguin, the evidence that ataxia was brought over with his expedition is compelling,” says Dr Susan Chamberlain, of the biochemistry department at St Mary’s Hospital, London. From that one affected expedition member, a vast pyramid of suffering has since been spreading over the centuries until the disease has reached its current widespread proportions. “In the end, ataxia patients have to use wheelchairs, their speech becomes slurred, and most face a shortened lifespan,” says Dr Chamberlain, the principal British scientist working on the project. Dr Chamberlain’s involvement began when a leading Cuban geneticist, Dr Guillermo Orozco, asked for help in countering Cuba’s ataxia problem. The condition causes particular anguish because it is a

dominant genetic disease which means an affected person has a 50 per cent chance of passing it on to his or her children. As symptoms do not begin until the victims are in their early 20s, this often means they have begun families unaware that they might be passing on a lethal gene. However, recent developments in molecular biology have brought hope to many families afflicted by inherited diseases, and these techniques are now being used in Cuba. First, Dr Chamberlain and her colleague, a neurologist. Dr Georg Auburger, visited Holguin where they took tissue samples from both victims and unaffected members of ataxia families. Now they are searching through these samples to find a characteristic piece of DNA — the chemical from which our genes are made — that distinguishes victims from unaffected people. The DNA fragment does not have to be the mutant ataxia gene itself, but could be a piece lying near the gene on the same chromosome and which is inherited with it. By pin-pointing those with the DNA section, called a marker, doctors can spot those who will later succumb to ataxia. And once that has been achieved, pregnant women can be screened to determine if their unborn child will later succumb to ataxia. Those affected will be offered abortions, a procedure that should slowly lead to eradication of ataxia. These techniques have been developed for tackling genetic diseases such as muscular dystrophy and cystic fibrosis and are already used in Cuba’s advanced medical service. “Once we get a genetic marker for ataxia, we will be able to screen very quickly,” says Dr Chamberlain. “And we are confident we can get one fairly soon because we think we know on which chromosome the gene lies.” If they are successful, Cuba will then be well down the road to countering its ataxia affliction — for the first time in 500 years.