Direct DNA analysis in family studies.

Restriction fragment length polymorphisms can be followed through families to track the incidence of genetic disease. Either cloned genes or anonymous DNA fragments, closely linked to the disease locus, may be used. 10 mL of blood collected into EDTA provide an excellent source of DNA and the blood is suitable for up to 3 days. In addition to gene tracking, the gene mutation itself may be studied to determine whether there is a DNA deletion.