Genetic diseases are caused by mutations, or changes in the DNA, which result in loss of function or altered function of a protein.  These changes in the DNA can be detected, even in the absence of disease symptoms, by isolating DNA from the patient and using various molecular biology lab techniques to detect the mutation. The following cases illustrate different types of DNA mutations associated with human genetic diseases, as well as different lab techniques, including restriction enzyme digestion and restriction fragment length polymorphism (RFLP), Southern blot, polymerase chain reaction (PCR), and dot blot. Each case scenario indicates which technique to use, and the necessary sequences (DNA samples, primers, probes) are found in the case folder.

Techniques used here do not necessarily represent what would currently be done in a clinical laboratory, as DNA sequencing is increasingly being used for diagnosis. Our cases are intended to illustrate the variety of techniques that have been used to detect DNA differences, and are designed to sharpen students’ analytical skills.

Keys to cases are available (instructors only) – contact mark.s.bergland@uwrf for access.

Terminology:  For the genetic disease cases, the term “normal” is generally used to refer to DNA samples or probes without the disease mutation, i.e. the normal or most common sequence for this DNA.  No value judgment regarding individuals who have inherited the disease-associated mutations is intended or implied.