07 June 2012 | General, BMBS
Do ‘Caucasians’ really exist?

The term 'Caucasian' was first used by Johan Friedrich Blumenbach, a German naturalist, at the end of the 18th century to describe all populations from Europe and surrounding areas. However, today Europeans are characterised by an extremely wide diversity in appearances, such as hair and eye colour, body height and the use of almost 50 different languages.

In addition, the analysis of molecular markers belonging to a metabolic process of milk digestion also demonstrates large differences within the European population. 75 % of adult human beings are unable to digest milk sugar lactose, and develop a condition known as lactose intolerance also called lactase deficiency and hypolactasia upon consumption of milk-derived products. This condition develops since the enzyme involved in lactose digestion - called lactase - loses its activity in adults after weaning. On a European scale, adult southern Europeans are unable to digest milk, while some of the northern Europeans are very well adapted to milk consumption because they have genetically retained enzyme activity. From this point of view, the term Caucasian is therefore a rather ‘crude’ simplification that does not reflect European genetic diversity.

COST Action BM0803 ‘A European network of the HLA diversity for histocompatibility, clinical transplantation, epidemiology and population genetics’ (HLA-NET) now provides additional molecular data to further corroborate this notion and has as main objective the characterisation of genetic diversity among Europeans.

Scientists involved in HLA-NET used the human leukocyte antigen (HLA) system located within the major histocompatibility complex (MHC) present on chromosome 6 to unravel European diversity. This distinct MHC complex contains a large number of genes coding for proteins that are key factors in organ transplantation. Such HLA proteins constitute a unique make-up of each individual and are particularly important in tissue and organ transplantation when matching donor and transplant recipient. They play a vital role in whether or not ‘non HLA-compatible’ tissues are rejected by the recipient or not.

Over the last three years, the networking activities carried out within HLA-NE produced an impressive dataset on European HLA genetic diversity. The Action provided standards for population genetic analysis, transplantation and epidemiology, while adopting international legislation and recommendations related to genetic analysis. HLA-NET now highlights the importance of retaining the maximal amount of information when collecting data concerning genetic HLA typing, including all ambiguities and genetic diversities. This is in contrast to current practices used by the National Marrow Donor Program coding system.

The Action summarised these recommendations in a recent article published in the International Journal of Immunogenetics (A. Sanchez-Mazas et al.; 2012, 00, 1-18), which describes in detail the outcome of pan-European networking efforts in HLA-based mapping of European population diversity.

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Dr Magdalena Radwanska
Senior Science Officer Biomedicine and Molecular Biosciences
COST Office