What does a “+” or a “-” mean after P40? Ive seen P40- and P40+, for example.
The + means you tested positive for that SNP (Single Nucleotide Polymorphism) mutation and the – means you were negative for that marker mutation. P40 is the marker’s name. 32. Does a P40- mean that there was no P40 marker at all, or that it existed but there were no repeats for it? The P40 marker is a single nucleotide on the Y chromosome which exists in two states … the original state (for example a C) and the mutated state (for example a T). It does not have a repeat pattern. It is a single nucleotide polymorphism, i.e., a SNP (pronounced “snip”). If the male tested and was found to have the original C value at that SNP location he would be P40-. If he had the mutated value of T at that SNP location he would be P40+ Repeat patterns are associated with YSTR markers, not SNP markers. YSTR markers contain multiple nucleotides in a row in a pattern such as: GATAGATAGATAGATA which is a 4 count repeat of the nucleotide pattern/motif GATA. Family Tree DNA Specific 33.
