II. Forensic applications.

Terms

NOTE Dr. Dennis Lockerman, director of the DNA crime laboratory at the Texas Department of Public Safety, will be the guest speaker. This is one you won't want to miss!

I. A DNA profile (fingerprint) is the name given to an array of genetic markers that are useful in distinguishing one individual from others and for establishing genetic relationships between persons.

A. RFLP's were the first markers to be used for this purpose. In particular, several DNA probes detect hypervariable (highly polymorphic) sites at more than one locus. This gives a high yield of information for the effort.

B. Microsatellites have made DNA profiles even more informative because there are very many loci with multiple polymorphic alleles. Furthermore, since microsatellite detection requires PCR to generate DNA fragments, the starting materials can be infinitessimal in amount.

A small drop of blood.
Saliva from a stamp.
A semen stain.
Old bones.

1. Paternity suits. The question usually reduces to, "Does the child have markers that must have come from someone other than the putative father?"

2. Matching evidence (DNA) left at a crime with the DNA of suspects.

3. Matching DNA from unidentified victims (bodies, bones, hair, etc.) with authentic DNA from missing persons or from their relatives.

Victims of major catastrophes.
Persons kidnapped as children.
Military personnel killed in action.
Victims of crimes. E.g. the family of the Tsar.

4. When attempting to identify an unknown with possible family members, it is advantageous to use mitochondrial DNA markers because (1) mitochondrial variations do not segregate and the victim's mitochondria should be identical to all maternal relatives related through females, and (2) there are many more copies of mitochondrial DNA in a cell that there are nuclear genes.

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