Chapter 28 : Forensic DNA Typing

Abstract:

One of the early goals of researchers was to relate known genetic differences in humans, such as hemoglobin differences related to various anemias, to base sequence changes in DNA. The first DNA-typing techniques were based on the minisatellites and used restriction fragment length polymorphism as the typing method. In criminal cases, DNA typing is used to exclude the possibility that a given suspect left DNA-containing evidence at a crime scene. Some crimes have been solved by analysis of DNA that did not come from humans. DNA testing can also be used to establish paternity or maternity. Since an offspring inherits half its chromosomes from its mother and half from its father, its DNA profile should show contributions from both. To establish paternity, profiles of the child, mother, and putative father are generated. The child’s DNA profile is compared to the mother’s, and the bands that match are subtracted. The remainder of the bands in the child’s profile should match bands in the father’s. DNA testing can also establish whether human remains are male or female. Normally, scientists can make that determination based on measurements of the skeleton (if other evidence is not available), but when the skeleton is badly fragmented (or parts of it are missing), it may not be possible. In humans, gender is determined by the so-called sex chromosome.