In the November issue of The American Journal of Human Genetics, work by researchers in Colombia and Britain suggests that the current population of the Colombian province of Antioquia is derived from a highly asymmetric mating pattern between European males and Native females. Not only is this interesting from a historical viewpoint, this mixed population may prove useful for the identification of disease genes.

The data in this work by Carvajal-Carmona et al. show that 94% of the Y chromosomes in this population are of European derivation, predominantly from southern Spain. Since Y chromosomes are passed only from father to son, this result suggests that few Native males contributed to the current Antioquian population. In contrast, about 90% of the mtDNA, which is passed only from mother to child, is derived from Native Americans. These data support historical evidence that Spanish males immigrated to the New World without spouses and that, historically, few European women overall immigrated with them. Further analysis of the current Antioquian gene pool demonstrated that Europeans, who, as stated above were largely male, played a larger genetic role in establishing the current population than did Native Americans. Although the reason for this finding is not clear, one hypothesis is that catastrophic mortality rates in Native Americans during the development of the New World led to a decrease in this population, relative to the number of immigrating Europeans.

This study of the Antioquian population is part of a large effort by genetic researchers to study the genetic histories of a variety of populations all over the world. Their hope is that they will identify populations that are ideally suited to mapping disease genes. Mixed populations, such as the Antioquians, show more linkage disequilibrium than others. That is, there is an increased likelihood that two genetic elements on a chromosome will both be passed from parent to child. This increases the likelihood that an identifiable genetic marker will be transmitted to a child along with a disease gene, making it easier to identify that disease gene by tracking the associated marker through affected families. No single population will be ideal for mapping all disease genes, but researchers hope that they can identify populations that have a distribution of linkage disequilibrium in the genetic region of interest that will facilitate the identification of a particular disease gene.

For the full text of this article entitled "Strong Amerind/Caucasoid gender bias and a possible Sephardic contribution among the founders of a population in North West Colombia", please see the electronic version of the November issue of The American Journal of Human Genetics at www.ajhg.org.

For further information, contact the corresponding author:
Andres Ruiz-Linares, Dept. of Biology, University College London
4 Stephenson Way, London NW1 2HE.
Phone: 44 (0)20 8869 3537
Fax: 44 (0)20 8869 3167
Email: andres.ruiz@ic.ac.uk

Contributed by: Kate Beauregard, The American Journal of Human Genetics.
Phone: (404)712-9985
Email: kbeaure@emory.edu