Prometaphase chromosome analysis as a routine diagnostic technique.

The use of techniques for the production of prometaphase chromosomes leading to increased resolution of banding patterns has resulted in problems as well as advantages in their routine use. A simple technique utilising the folate antagonist methotrexate has been in use in this regional diagnostic cytogenetics centre for three years, and a number of chromosome abnormalities have been detected in cases previously reported as normal following G banding studies. With reference to this, the routine analysis of prometaphase-type chromosomes is discussed and assessed.