President's DNA Initiative
Advancing Justice Through DNA Technology
DNA Analyst Training
previous pagenext page

Positive Control(s)

Home > STR Data Analysis & Interpretation > Data Interpretation and Allele Calls > Step 1: Internal Size Standards and Allelic Ladders > Positive Control(s)
Positive Control 9947A
Profiler Plus®

Positive Control 9947A-Profiler Plus®
Click for larger image

Positive controls are included in most commercial DNA analysis kits used for quantitation or STR typing. Applied Biosystems and Promega STR kits both include 9947A control DNA for use as a positive amplification control. The control is usually amplified with each batch of samples and aids in determining the overall performance of the amplification and typing procedures. 9947A is a female cell line from a 31 year old Caucasian female. The cell type is B-lymphocyte from a blood sample.  This cell line is used as a positive control in forensic DNA analysis.

Online Link

The positive control should show the expected alleles. If no peaks are seen, this may indicate a problem with the amplification or injection. In the event that the positive control does not yield the correct results, analysts should troubleshoot the problem and follow the procedures established by the laboratory.


It is expected that injection issues would have been identified in the internal size standard evaluation step.

< Previous Page  ::  Next Page >

© 2007 NFSTC Science Serving Justice®
NOTE TO USERS: The President’s DNA Initiative DNA Analyst Training program and assessment were completed and published in 2005, in cooperation with the National Institute of Justice. The science and techniques in the program are sound and proven, however, program content has not been updated to include tools and technologies developed and in use after 2005, including many kits and robots. Assessment questions address only content delivered in this program and may not contain the full range of tools in use in your laboratory.