First woman Genome

In 2001, the DNA sequence was published of a combination of persons. The DNA sequences of Jim Watson, discoverer of the DNA’s double helix structure, followed in 2007, and later the DNA of gene hunter Craig Venter. Recently the completion of the sequences of two Yoruba-Africans was announced.

Geneticists of Leiden University Medical Centre (LUMC) are the first to determine the DNA sequence of a woman. This research was announced by the researchers May 26, 2008 at ‘Bessensap’, a yearly meeting of scientists and the press in the Netherlands.

She is also the first European whose DNA sequence has been determined. The results will contribute to insights into human genetic diversity.

DNA of geneticist Marjolein Kriek

The DNA is that of Dr. Marjolein Kriek, a clinical geneticist at LUMC. Professor Gert-Jan B van Ommen, leader of the LUMC team and director of the ‘Center for Medical Systems Biology’ (CMSB), a center of the Netherlands Genomics Initiative women do not have a Y-chromosome, they have two X-chromosomes. As the X-chromosome is present as a single copy in half the population, the males, it has undergone a harsher selection in human evolution. This has made it less variable. We considered that sequencing only males, for ‘completeness’, slows insight into X-chromosome varialibity. So it was time, after sequencing four males, to balance the genders a bit”.

Eight times coverage

The DNA sequencing was done with the Illumina 1G equipment. In total, approx. 22 billion base pairs (the ‘letters’ of the DNA language) were read. That is almost eight times the size of the human genome.

The sequencing itself took about six months. Partly since it was run as a ‘side operation’ filling the empty positions on the machine while running other projects. Would such a job be done in one go, it would take just ten weeks.

The cost of the project was approximately €40.000.- This does not include further in-depth bioinformatics analysis. This is estimated to take another six months.