Analysts expect the market for DNA probes to grow a hefty 20% a year from now through 2006, but presently the segment is still a relatively small part of the $18-$20 billion diagnostics products industry. Worldwide sales of DNA probes now total $600 million or so, which tells Jack Johansen, PhD, CEO of Boston Probes Inc. that other new probe-based technologies stand a good chance of gaining acceptance.