Genetic diagnostic technology is rapidly improving. DNA or RNA can be amplified, producing many copies of a gene or gene segment, using PCR.

Gene probes can be used to locate specific segments of normal or mutated DNA. A known DNA segment may be cloned and then radioactively or fluorescently tagged; this segment is then combined with a test specimen. The tagged DNA binds to its complementary DNA segment and can be detected by measuring the radioactivity or the amount and type of fluorescence. Gene probes can detect a number of disorders before and after birth. In the future, gene probes will probably be used to test people for many major genetic disorders simultaneously.

Microchips are powerful new tools that can be used to identify DNA mutations, pieces of RNA, or proteins. A single chip can test for 30,000 different DNA changes using only one sample.

Last full review/revision May 2007 by Judith G. Hall, MD

Content last modified February 2012