Identification of the male sex

Up until the beginning of the last century it was generally believed that in humans sex was determined by environmental factors such as maternal nutrition. With the discovery of the human X and Y chromosomes in the early 1920s (Painter, 1923) it was first assumed that the number of X chromosomes determined the sex of a human individual. It took an additional 36 years to establish that sex determination in humans and other mammals is independent from the number of X chromosomes and that the...

Analysis of STR data

The review of STR data can be relatively straightforward for pristine, single-source specimens such as those collected from convicted offenders. Still, regardless of sample type, a number of samples will present some anomalous features that may interfere with the final allele call and genotype assignment. Most anomalies (e.g. pull-up, saturated and split peaks, elevated baseline, heterozygote ratio imbalance, elevated stutter, profile slope) will present electrophoretic data signatures that can...

Minisatellite variable repeat MVRPCR

The majority of minisatellite loci consist of heterogeneous arrays of two or more repeat unit types (MVRs) that differ slightly. The human hypervariable minisatellites characterized to date vary not only in the number of repeat copies (allele length) but also in the interspersion pattern of variant repeat units within the array. This internal variation provides a highly informative approach to the study of allelic variation and the processes of mutation. Interspersion patterns can be determined...

Identification of a males geographical origin

The third forensic application of Y-chromosomal DNA polymorphisms is in the identification of the geographical origin or genetic ancestry of an unknown male individual. Since this is the most recent application of Y-chromosomal markers to forensics, it deserves a somewhat more detailed summary. Geographical origin or, in other words, genetic ancestry identification is important in forensic cases with no known suspects. In such cases it would be helpful for the police to be able to concentrate...