Termination of Sequencing Chromatogram Printout Services


Effective at the start of business on 01-Feb-05, we will no longer be printing
DNA sequencing chromatograms.

These printouts have become increasingly obsolete and increasingly difficult
to produce and to justify. The information they provide is poor and sometimes
even misleading, since one frequently cannot judge the shape of the peaks and
thus cannot ascertain the quality of the resulting base calls.

We STRONGLY encourage all of our clients to download and view the electronic
chromatogram files. These are far and away superior to any hard-copy printouts
in several respects:

  • Electronic chromats are cheaper and easier - for client and Core alike.
    Chromatogram viewing programs are easily available for most computer
    systems (often for free) and links to them are provided in the instructions
    page for our Download Results section.

  • Those viewing programs allow you to see even the smallest peaks, so any
    flaws (baseline noise, distorted shape, mis-spacing) are quickly detected.
    Printouts are inferior for assessing the validity of your basecalls.

  • Chromatograms can be utilized by a large variety of ancillary programs
    that help you to detect heterozygous peaks, identify point mutations and
    perform sequence matching or assembly. If you're trying to eyeball your
    sequence, you're just wasting valuable time.

I would be happy to help you with problems in downloading data; feel free to
give me a call (at 4-8531), email me (boblyons@umich.edu), or simply stop by
my office in 2560 MSRB II.

Please note that printouts for microsatellite genotyping will continue for now,
since some of our genotyping clients do not have easy access to programs suitable
for viewing their chromatogram files.

And, as we always emphasize ....

If you aren't looking at your chromatograms, the sequence is USELESS!


Dr. Robert Lyons,
Director, UM DNA Sequencing Core
22-Dec-04