The DYS, DYZ, and DYF prefixes are part of the scientific name for a short tandem repeat (STR) found on the Y chromosome. STR markers are named according to guidelines published by the HUGO Gene nomenclature committee. For Y-DNA STR tests:
- D stands for DNA.
- Y stands for Y chromosome.
- S, Z, and F stands for the complexity of the repeat segment as follows:
- S is a unique segment.
- Z is a number of repetitive segments at one site.
- F is a segment that has multiple copies on the Y chromosome.
- All STRs are given a unique identification number.
For example, DYS393: the D indicates that the segment is a DNA segment, the Y indicates that the segment is on the Y chromosome, the S indicates that it is a unique segment, and the number 393 is the identifier.