Y-STR analysis focuses on short tandem repeats (STRs) found on the Y chromosome, only carried by male individuals

For forensic labs, the most common application of Y-STRs is in criminal cases such as sexual assault, where evidence samples are difficult to resolve with traditional autosomal STR analysis due to low amounts of male DNA present in a high background of female DNA.

Y-STR analysis is also a valuable tool to trace familial relationships among males, to help identify missing persons, and to assess paternal relationships when the alleged father is not available.


The Yfiler Plus PCR Amplification Kit is now approved for use by laboratories generating DNA profiles for inclusion to the US National DNA Index System (NDIS), the national level of the Combined DNA Index System (CODIS) database.

Latest Yfiler Plus PCR Amplification kit

In order to help maximize discrimination capability and provide optimum results when used with the latest generation Applied Biosystems Quantifiler Trio DNA Quantification Kit and STR kit (GlobalFiler PCR Amplification Kit), we have built our Yfiler Plus PCR Amplification Kit. The Yfiler Plus kit leverages 6-Dye technology and contains 27 Y-STR markers.

See product comparisons  Request details

 Flyer: Yfiler Plus PCR Amplification Kit

Powerful discrimination capacity, particularly between closely related males
  • Includes 7 rapidly mutating Y-STRs
  • Concordant with 17 markers of Yfiler and Yfiler Direct kits
High performance with challenging samples
  • 11 mini- STRs (<220 bp)
  • Highly robust chemistry to overcome PCR inhibitors
Easy interpretation
  • 6-Dye Chemistry enables expanded allelic ladder for easier data analysis

Customer videos

Optimizing the sexual assault workflow: Applied Biosystems Quantifiler Trio, Yfiler Plus and Identifiler kits

Donna Foskin, senior scientist, from the Institute of Environmental Science and Research (ESR) describes their workflow optimization for processing sexual assault kits using forensic DNA analysis.

Why should Forensic labs use Y-STR analysis in sexual assault cases

In many sexual assault cases, standard autosomal STR typing does not yield a probative result due to large quantities of female DNA and very little male DNA. Dr. Jack Ballantyne from the University of Central Florida explains that Y-STR analysis can help in such cases and it is a mere extension of standard methodology that labs are using today.

Customer quotes
“The inhibited samples are quite impressive.”
“I thought the kit was great! I really like how fast the
amplification was.”
“One of the samples I tested was an old paternity
proficiency and guess what, I can differentiate son and
dad at one of the RM loci! Pretty neat.”
“I also ran a lab staff with a known null at DYS448 and
he is still a null. We have another lab staff with 2 peaks
at DYS438 in Yfiler and he still has the 2 peaks in
Yfiler Plus.”
“A full mixture profile for haplotypes of both males
is obtained for all dilutions.”
“I typed low amounts of male (100-–300 pg) in the
presence of 250 ng of female DNA and overall
the balance was pretty good.”
“I like how you expanded some of the loci. We had
another lab staff and a proficiency sample with peaks
that were outside of the old Yfiler marker ranges but
now they are in a bin.”

Y-STR product comparison

Yfiler Plus kit

Yfiler kit,
Yfiler Direct kit

Number of loci2717
Total rapid mutating loci7N/A
Discrimination capacityExcellentVery good
Dye technology6-Dye Chemistry5-dye
Allelic ladder345137
Virtual bins17972
Mini-STRs (<220 bp)118
Amplification time (min)~90>180
Casework Amp protocolYfiler kit
Database (direct) Amp protocolYfiler Direct kit
Fully integrated workflowExcellent:
Quantifiler Trio + 6-Dye Autosomal-STR kits
Very good:
Quantifiler Duo + 5-Dye
Autosomal-STR kits
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Learn more about Y-STR analysis


Webinar: Enhancing the Sexual Assault DNA Workflow
Jack Ballantyne introduces how our Quantifiler Trio, Yfiler Plus, and GlobalFiler kits work in tandem to help improve the DNA analysis workflow for sexual assault samples.

Webinar: Y-STR Statistics Workshop
Bruce Budowle, Aurthur Eisenberg, and John Planz discuss STR statistics.

Publication on value of rapidly mutating Y-STRs

Toward male individualization with rapidly mutating y-chromosomal short tandem repeats.
Rapidly mutating Y-STR loci can help discriminate between closely related male relatives. Learn more about them in this publication. (2014) Hum Mutat. 35(8):1021-1032. doi: 10.1002/humu.22599. Epub 2014 Jul 14.

Useful information to get started with Y-STR analysis in your lab

 SWGDAM Interpretation Guidelines for Y-Chromosome STR Typing - 2014
If you or the law enforcement agencies you support are thinking about bringing Y-STR analysis online or are looking for ways to improve your current practice, this guide will help you get started. The guidelines address interpretation of results, including mixtures, as well as statistical interpretation using Y-STR haplotype databases.

Y chromosome STR typing in crime casework 
Review paper on Y-STR analysis addressing applications and usage in forensic casework settings. (2009) Forensic Sci Med Pathol. 5(2):77-84. doi: 10.1007/s12024-009-9089-5. Epub 2009 May 20.

Interpreting Y chromosome STR haplotype mixture 
Assessment of mixtures from Y-STRs differs from traditional autosomal STRs, due to lack of recombination. Learn how to best augment your lab’s forensic insight with this capability. (2010) Leg Med (Tokyo). 12(3):137-143. doi: 10.1016/j.legalmed.2010.02.003. Epub 2010 Mar 25.

  10 Tips for Testifying to Y-STR Results
Learn best practices for testifying in court for cases involving Y-STR analysis (Forensic News 2009).

Using the Y-STR Haplotype Reference Database (YHRD)

For Research Forensic or Paternity Use Only. Not for use in diagnostic procedures.

For licensing and limited use restrictions visit thermofisher.com/HIDlicensing