X–SV test
Sometimes X–SV tests are simply referred to as female lineage tests. To understand what an X–SV test is, it helps to know a little more about chromosomes. The ‘X’ in the X–SV test relates to the X chromosome. This is sometimes referred to as the ‘female chromosome’.
All humans have two chromosomes in every cell of their body. While women have a pair of X chromosomes, men have one Y and one X, instead. By looking at the DNA taken from an X chromosome, from one sample, laboratory technicians can see whether there are any patterns which match the DNA of another sample.
If there are patterns and the DNA matches then the two people which the samples came from could be proven to be mother and daughter, for example, or sisters from the same mother. If however, the samples don’t have matching sequences of nucleotides (lines of DNA) then the two people would be revealed to be unrelated to each other by maternity. This means that they would not have the same mother or share DNA with their purported grandmother, or sister (depending on who the samples came from).
X–SV tests are only useful for finding out about maternal lineage, so it’s possible to determine whether an estranged mother and daughter are related, for example but not find out anything about a father. Something interesting about X–SV tests is that men don’t pass on the X–SV DNA to their children, but women do. Men still inherit the X–SV DNA from their mother; they just don’t pass it on to their own children.
