Externally visible characteristics of the cell donor

Another aspect of retrieving donor information from forensic samples that may be useful for investigative intelligence purposes to find an unknown person is to directly predict appearance traits of the sample donor. Finding out what the sample donor looks like may be of even more relevance for leading police investigation than knowing the bio-geographic ancestry, although both may potentially be used in combination. Unfortunately, the genetic understanding of human appearance traits is still limited and so far we know much more about the underlying genetics of numerous diseases than about our looks.

In this research line we perform systematic scans of the entire human genome (using SNP chips) of large numbers of individuals for with appearance traits information is available to us (such as eye color, hair color, skin color, height, facial dimensions etc.) and use statistical methods to find genes involved in human physical appearance. We are also using other biomarkers such as RNA and methylated DNA for investigating appearance traits. We are then applying such data in dedicated algorithms and performing model-based prediction analyses of appearance traits. We recently exemplified this approach for human eye color, first finding new genes involved in eye color variation; then showing that eye color can be predicted from DNA markers with high accuracy, to finally developing a DNA-test for eye color prediction customized for forensic applications. The prediction of more appearance traits using molecular approaches will follow this initial success. In the end we plan to develop tools to accurately and reliably predict appearance traits from biological samples such as those found at crime scenes that take into account the specific requirements of forensic DNA analysis (high sensitivity, multiplexing etc.).