Bad habits - or bad genes?: The Finns

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Bad habits - or bad genes?

The Finns have the lowest life expectancy in Europe. But it's not all down

to their unhealthy lifestyle. Steve Connor reports

15 September 2004

http://news.independent.co.uk/world/science_technology/story.jsp?story=56169

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The people of eastern Finland are famous for being ill. They have the

dubious distinction of having one of the highest rates of heart disease in

the world. They also suffer more than their fair share of diabetes, high

blood pressure, schizophrenia and depression. In eastern Finland, the infant

mortality rate is one of the lowest found in the developed world, yet by the

time people reach middle age, their life expectancy falls well short of

other Europeans.

 

The mystery of why the Finns - particularly those who live in the eastern

province of Savo, close to the border with Russia - are so prone to some of

the most lethal disorders of the Western world has been a longstanding

conundrum. But it is one that is slowly being solved with the help of a

meticulous study of local families, combined with the scientific power

provided by the deciphering of the human genome.

 

Scientists involved in a 20-year project to unravel the role of genes and

lifestyle on the health of the eastern Finns believe they are at last

beginning to find possible answers to the question of why this isolated

group is so prone to illness. Solving the problem has wide-reaching

implications. It could help to explain why other areas of the world are also

experiencing epidemics of heart disease, diabetes and the other serious

disorders of later life.

 

Finland has for years come top - or close to the top - of the European

league table of mortality rates from circulatory diseases such as heart

disease and stroke. Its eastern province of Savo, around the small city of

Kuopio, has historically fared even worse than the national average in

potentially lethal diseases of middle age.

 

An obvious explanation was the notoriously fatty diet of the Finns, which

has by necessity evolved to provide the body with vital sustenance during

the long and bitterly cold Nordic winters. Full-fat milk is still regularly

drunk with meals, and the people of Savo, the Savolainen, are partial to

heart-attacks-on-a-plate, such as Karelian pies, a stodgy concoction of

pastry filled with mashed potato or rice and liberally smeared with butter

and chopped egg.

 

Then there are the notorious drinking habits of the eastern Finns. Although

they do not drink that much per head (not as much, for instance, as do the

French or Italians), what they do drink is almost always consumed in one

sitting and for one purpose - to get drunk.

 

However, while the drinking and diet of the eastern Finns is not noted for

being particularly healthy, neither is it so different from that of other

Finns - or, indeed, the rest of northern Europe. Food and drink, in other

words, cannot explain why this group of Europeans suffers so badly with the

diseases of the Western lifestyle.

 

The real answer lies in the unique history of the eastern Finns, which has

exacerbated their genetic isolation. A limited influx of genes from other

parts of the world, and the resulting inbreeding, has exaggerated any

genetic defects. This group of people is, therefore, the best population for

geneticists to study in order to tease apart the complex interaction of

genes and lifestyle on long-term health.

 

From her base at the University of Helsinki, Professor Leena Peltonen has

spent much of her life contemplating the respective role of nature and

nurture on the health of the eastern Finns. After many years of research,

Professor Peltonen, a medical geneticist, has helped to explain how the

history of the eastern Finns has led to the sharing of certain genetic

traits that have predisposed them to the illnesses they suffer from today.

 

" The genes of this population are better known than any other population, "

Professor Peltonen says. " The diseased genes of the Finnish population have

definitely made what I would say is a landmark in disease genetics, simply

because Finns are isolated and they have remained isolated for hundreds of

years, " she explains.

 

Sandwiched between two powerful neighbours - Russia and Sweden - who have in

the past both ruled Finland, the eastern Finns are in many way the medical

victims of colonial conflicts stemming back many centuries. It really began

in the 16th century when the Swedish King Gustavus of Vasa ordered the mass

movement of Finnish-speaking families from the south and west of Finland

into the sparsely populated eastern interior to act as a buffer against

Russian encroachment.

 

Historians estimate that between 40 and 60 " founder families " made up this

migration and that these people subsequently gave rise to the bulk of the

population living in eastern Finland today. However, the growth of this

pioneer population was not without its setbacks. Famine and plague ripped

through the small rural community creating a " genetic bottleneck " - when the

population crashes and becomes small enough to limit the diversity of genes

inherited in subsequent generations.

 

In scientific terms, this results in a dramatic shrinkage of the available

gene pool. More simply, it means that the eastern Finns today are a

relatively inbred population, made up of people with an unusually

homogeneous array of genetic traits.

 

What is unusual is that this genetic homogeneity was maintained for

centuries simply because so few people migrated into the region. The

geographical, religious and linguistic isolation of the eastern Finns helped

to maintain a common genetic inheritance that is still prevalent to this

day.

 

" There is some inbreeding, but it's typically not recognised, " Professor

Peltonen says. " People don't know that they are related because their

relationships are so old - people could have been related seven generations

ago. "

 

It is this combination of events - a small founder population, severe

genetic bottlenecks and generations of intermarriage - that has turned the

eastern Finns into perfect experimental material.

 

Professor Peltonen says that scientists have already identified 31 different

disease-causing genes as a result of studying the Finns, especially those

living in the eastern region of Savo. " The Finnish population is the best

characterised population in the world with regard to these genes, " she

explains. " It's a unique setting. If you monitor all of these 31 disease

mutations, one Finn in three carries at least one of them. "

 

There is an additional factor that makes the eastern Finns such good study

material. In 1634, the then Swedish king established detailed church records

for taxation purposes. This record-keeping has continued with Finland's

modern health service, which follows every Finn from birth to death and has

the records to prove it.

 

" Finland is one of the best places on the globe to study these complex

diseases because we have this wonderful, isolated population, but we also

have high-quality, socialised healthcare that produces good records, "

Professor Peltonen says.

 

The study of human genes and the unravelling of the human genome still

relies on piecing together the DNA jigsaw of life by studying people who are

in some way related to one another, either as a family or as a relatively

inbred, homogeneous population. It is a study that has produced important

medical breakthroughs with potentially lucrative spin-offs.

 

A Finnish company called Jurilab, set up with the help of government money,

has exploited this wealth of record-keeping and genetic information to

discover the genes that could account for the poor health of the eastern

Finns today. Professor Jukka Salonen, Jurilab's chief scientific officer,

says that some 6,000 different items of health information have been

collected on about 3,000 people since the project on heart disease first

began in 1984.

 

" This was the first population to be studied where DNA was collected, "

Professor Salonen says. " The resulting wealth of medical and social

information has resulted in the world's most comprehensive DNA and data

bank. "

 

Jurilab scientists are working on a gene involved in triggering type-2

diabetes, a gene that plays a role in hypertension and a genetic test to

identify people whose livers are capable of breaking down prescription drugs

too fast for the medicines to work properly. The potential income from a

diagnostic test for just one of these could run into hundreds of millions of

pounds.

 

Such breakthroughs have come out of studying the DNA of local Savo people

such as Pekka Ropponen, a 56-year-old former construction foreman. Like his

two sisters and three brothers, Ropponen suffers from high blood pressure -

hypertension. One of the benefits of taking part in the study, he says, is

recognising that if family members have hypertension, you are also at risk;

and that you can do something to help yourself by taking exercise, cutting

down on salt and watching your weight.

 

Professor Salonen said that Finns such as Ropponen take part in the research

because they are interested in finding out about why their health is so

poor. " These people know about these diseases a lot. They see their family

members dying of coronary heart disease and diabetes. It affects their

lives, " says Professor Salonen.

 

Knowing that you, your family and your nearest community is at such a high

risk of heart disease, hypertension or diabetes can have its negative side.

Professor Salonen used to frequent a run-down petrol station owned by a man

with three brothers who had all died of heart attacks before the age of 40.

The reason the garage was run down was because the man believed there was no

reason to invest in the future, Professor Salonen says.

 

Despite their history of disease, there are signs that the Finns are finally

beginning to take note. Nationally, the rate of heart disease is falling as

younger people take up a healthier lifestyle than their parents. Despite the

disadvantages conferred by their genes, even the people of eastern Finland

are beginning to show signs of learning a healthy lesson in the art of

living well.

15 September 2004 15:31