Null425 Project by Charles Kerchner

Project Goals

The Null 425 yDNA Project was formed to gather data and learn more about haplotypes which have a Null result for ySTR marker DYS425. For how to join the project see the bottom of the "Project Background" section of this website.

Also, if not already tested for DYF371X, people with a Null at DYS425 who are joining this project must order prior to joining this project the test for the advanced marker DYF371X to learn the specific allele values for this multi-copy marker. You don't need to know your test results for marker DYF371X when you join, but the test must at least be on order and in process. Ordering that marker test is easy and requires no new samples. It is a simple and inexpensive advanced marker test. The test for the multi-copy advanced marker DYF371X is available via your personal account page at FTDNA using the Order Tests link and then selecting the "Advanced Orders" section. Order that advanced marker prior to sending this project a "Join Request". Thank you.


This is what FamilyTreeDNA.com says about Nulls at DYS425 and its relationship to the advanced marker DYF371:

DYF371 is usually a four copy marker like DYS464. Its alleles are located on the palindromes P1 and P5 on the Y chromosome.

See Y Chromosome Palindromic Map

One of the copies on P5 can carry a mutation in the flanking region from C to T. This T-type allele was discovered as an independent marker and was called DYS425. Our lab has developed a test to detect the C- and T-type alleles for all DYF371 STR alleles simultaneously. This test is called DYF371X. We can see the T-type alleles and the C-type alleles in different fluorescent colors, so we can label each allele with c or t. A normal person without a NULL at DYS425 would look like 10c-12t-13c-14c for example. You will notice that in a DYS425 NULL result you don't have a T-type allele. This is because a C-type allele has overwritten the T-type allele during the RecLOH event. Other haplotypes may have two T-type alleles that may have occurred by the reverse copying process. Consequently these persons will have two DYS425 alleles.

Some persons who get a DYF371 result may notice that they have an odd number of alleles at this marker (3 or 5). This occasionally happens if a deletion or duplication occurs at the large P1 palindrome. Asymmetric markers that are located on different palindromes make such events visible while regular multi-copy markers (like DYS459, CDY, DYS464) are hard to figure out their molar equivalents of alleles in each genome. If you have a deletion or duplication on P1, don't panic! Today we know that many (almost all) persons with abnormal palindromic conformations at P1 or P2 are still perfectly fertile and can produce healthy children. Even whole haplogroups (like N) carry a deletion at P1/P2 as one of their characteristic markers on their Y chromosome. If you want to find out more about possible RecLOH events, insertions or deletions on your Y chromosome we suggest ordering the markers from the Palindromic Pack (Panel 5).

Source: Presentation on Palindromic Markers at FTDNA conference 2006 by Thomas Krahn

See:
RecLOH at Wikipedia
Gene Conversioni at Wikipedia

Some papers with discussion of marker DYS425:
Diagnostic Y-STR Markers in Haplogroup G by Phillip G. Goff and T. Whit Athey