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RTD info logoMagazine on European Research N° 38 - July 2003   
 Europe's troubled seas
 Gutsy bacteria 
 Utopia on wheels

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Title  The triumphs of a gene hunter

Internationally recognised as a pioneer and one of the world's leading experts in molecular genetics, Leena Peltonen owes her vocation – and success – to her family background and country of origin. Her fascination with the 'innate' and the 'acquired' in determining the health of every individual led her to base her scientific investigations on the unique and isolated genetic pool of her native Finland. 

Leena Peltonen: 'The big question posed by research into the genetic origins of diseases is to distinguish between what really depends on the genetic make-up and what is linked to environmental factors.'

Leena Peltonen: 'The big question posed by research into the genetic origins of diseases is to distinguish between what really depends on the genetic make-up and what is linked to environmental factors.'
Leena was ten years old when her younger brother, two years her junior, became seriously ill. He was diagnosed as having an insidious disease which would affect him for life: juvenile-onset diabetes. 'As a little girl I felt both a sense of deep anguish and profound injustice. I thought I would get the disease too.' She decided to fight and refused to accept as inevitable this disease which was attacking her brother and frightening her: she would become a doctor. 

This drama unfolded in the small port of Oulu, on the Baltic coast, 600 km north of Helsinki and close to the Arctic Circle.   Remote as it is, the town has a school of medicine housing one of the best research departments in Finland. It is there that Leena Peltonen was introduced to the world of research, thanks in particular to her doctoral supervisor, Kari Kivirikko, a renowned specialist in the biochemistry of collagen and related dermatological diseases.  

Genetico-genealogical detective 

In 1978, increasingly fascinated by the genetic dimension of diseases, she stepped up her research activities and decided to make the most of the 'Finnish laboratory'. 'Traditionally isolated from Europe's principal migratory flows and comparatively small in number, the Finnish population – records of which have been kept meticulously since the 16th century – provides a uniquely interesting 'genealogical database', with a marked inbreeding due to a common ancestry which provides fertile ground for autosomal-recessive genetic transmission.'(1)

Pursuing a remarkable career as both 'genealogical detective' and 'gene hunter', this tenacious researcher followed up all the possible genetic leads behind a vast range of pathologies – both rare and common – which occur within the Finnish group. These range from Marfan's syndrome (resulting in excessive growth and a heart condition) to schizophrenia and other neuropsychiatric disorders, including familial combined hyperlipidemia, lactose intolerance and multiple sclerosis. 

From Finland to California
Over the years, Leena Peltonen has become recognised universally for the excellence of her research – first in her native Finland, where she was elected to the Academy of Sciences, appointed Chair at the University of Helsinki and, in 1987, charged with founding and heading up the Department of Human Genetics at the National Institute of Public Health. And subsequently abroad, where she participated in many international research programmes. 

In 1997, the School of Medicine at the very prestigious University of California, Los Angeles (UCLA) asked her to create and head a new department of genetics in the field of paediatrics and neuropsychiatry. 'I did not hesitate for long. It meant interrupting the comfortable scientific career I could have pursued in my own country, but the challenge of this expatriation was not something I could refuse.' Soon after she arrived in Los Angeles, accompanied by a whole team of Finnish researchers. 

This brilliant American interlude ended in 2002. She was beginning to miss Finland, and Europe, for its cultural traditions as well as for scientific reasons. 'With its variety of populations and characteristic lifestyles, our continent offers a wealth of raw material for demographic genetics. In addition to this diversity there are infrastructures and health systems of the highest quality, and a population with a high average level of education. These are all essential assets for research and create a unique environment to study genetic background of human diseases.' 

The twin laboratory

On her return to Finland, Leena Peltonen continued her investigations among the vast samples of ‘real population’ groups by launching an ambitious European research project which she had been aiming to do for some time: the systematic analysis of the genetic information provided by the medical observation of twins. 'The big question posed by research into the genetic origins of diseases is to distinguish between what depends on the expression of a given gene and  what is linked to environmental factors, i.e. lifestyles which could be the cause of good health or a pathological condition. In this respect, twins – and real twins have common genes – provide the ideal test population. They have also shared a common environment during their fœtal life and early childhood, both determining periods for the growth of the human being. Therefore, it is possible to analyse precisely the causes of any health problems later in life, depending on whether they share them genetically or display them because of their different lifestyles as adults.'

This ambitious project was made possible thanks to a unique wealth of data widely available within the Union. Six European countries – Finland, Sweden, Norway, Denmark, the Netherlands and Italy – have records dating back many years on the medical history of twin populations, making it possible today to study a total of around 600 000 pairs.  Ten research teams of epidemiologists, geneticists, mathematicians and bio-informaticians carried out an in-depth analysis of this 'documentary material'. 

The post-genomic revolution
The ultimate motivation for Leena Peltonen's latest research is the completion of the human genome project which she believes is a major scientific revolution. 'The complete sequencing of the human genome changes all our strategies. For the first time in history, we can start to examine the full genetic spectrum of the human being and the essential interactions which take place there, rather than just one gene at a time, or the role of just one of them in an illness, whether during growth or ageing. This will overturn the whole medical approach. When a patient sees a doctor about a specific illness, the doctor will be able to consult his genetic profile and the specific risks related to it. As a result of this information, he will be able to decide on preventive measures and treatment which are genuinely made to measure for each individual.'

But how does this leading geneticist, renowned for her excellence worldwide, view the prospect of human cloning? On this point, Leena Peltonen is categorical. There is no legitimate scientific justification for seeking to clone men and women. 'All the research data we have built up on twins tells us how marvellously different they are. No two identical individuals exist, even if their genetic make-up is exactly the same. The fascination some people have with human cloning reflects a kind of pathetic fear of death and an impossible desire for immortality. Although genetics is in the process of changing our knowledge of man so radically, it is absurd to think that one day he will be nothing more than the sum of his genes.'   

(1) A gene is said to be autosomal recessive when it produces the trait which is linked to it on the condition that it exists simultaneously in the X sex chromosome of the XX (male) and XY (female) constitutive pair.