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Statistical Genetics

Statistical Genetics

Statistical Genetics

Forensic DNA evidence is essential in modern societies to solve crime cases and other legal disputes to increase public safety. DNA is also used as evidence in paternity and family reunion cases. The central element in making this possible is to calculate the evidential weight of the DNA evidence. The evidential weight can only be calculated if the genetics and statistics of the DNA profiles are well understood. Modelling the genetic part of the evidence as well as the biotechn­ol­og­ical processes calls for statistical models.

For many applications of forensic genetics the probabilistic and statistical models are well understood and described by simple statistical models. However, several frequently occurring situations in crime case related forensic genetics impose more complicated scenarious to be modelled and accounted for. Hence, statistical models are needed in order to deal with e.g. DNA
mixtures, allelic drop-out, and/or degradation of the biological material. Other challenges are the introduction of newer and more sensitive biotechnological methods, e.g. sequencing, which implies models to be continuosly improved and refined.

In some applications of forensic genetics, the genetic component is less well understood, and fundamental problems need to be addressed. Linage markers (i.e. Y-chromosome and mitochondrial markers), which are passed from generation to generation with no or few recombinations impose a challenge due to their structural form.

Hence, recent research has focused on this area and how to improve the understanding of these haplotypes in the Y-chromosome and mitochondrial DNA. With more genetic markers becoming available through the introduction of DNA sequencing, methods for predicting phenotypes and physical appearance for investigative leads is being used more and more. Features such as eye, skin and hair colour can be predicted by some accuracy. Similarly, predictions of age and ancestry are possible through the use of genetic markers.