Y-DNA tests generally examine 10-67 STR markers on the Y chromosome but over 100 markers are available. STR test results provide the personal hapolotype. SNP results indicate the hapologroup.
Haplotype
A Y-DNA hapolotype is the numbered results of a genealogical Y-DNA test. Each allele value has a distinctive frequency within a population. For example, at DYS455, the results will show 8, 9, 10, 11 or 12 repeats, with 11 being most common[1]. For high marker tests the allele frequencies provide a signature for a surname lineage.
The test results are then compared to another project member's results to determine the time frame in which the two people shared a most recent common ancestor (MRCA). If the two tests match on 37 markers, there is a 50% probability that the MRCA was fewer than 5 generations ago and a 90% probability that the MRCA was fewer than 17 generations ago.
It is important to check the number of markers that will be tested before choosing a test. For example, the Genographic Project looks at only 12 markers, while most laboratories and surname projects recommend testing at least 25. The more markers that are tested, the more discriminating and powerful the results will be. A 12 marker STR test is usually not discriminating enough to provide conclusive results for a common surname.
STRs results may also indicate a likely hapologroup, though this can only be confirmed by specifically testing for that Haplogroups' single nucleotide polymorphisms (SNPs).
Haplotype
A Y-DNA hapolotype is the numbered results of a genealogical Y-DNA test. Each allele value has a distinctive frequency within a population. For example, at DYS455, the results will show 8, 9, 10, 11 or 12 repeats, with 11 being most common[1]. For high marker tests the allele frequencies provide a signature for a surname lineage.
The test results are then compared to another project member's results to determine the time frame in which the two people shared a most recent common ancestor (MRCA). If the two tests match on 37 markers, there is a 50% probability that the MRCA was fewer than 5 generations ago and a 90% probability that the MRCA was fewer than 17 generations ago.
It is important to check the number of markers that will be tested before choosing a test. For example, the Genographic Project looks at only 12 markers, while most laboratories and surname projects recommend testing at least 25. The more markers that are tested, the more discriminating and powerful the results will be. A 12 marker STR test is usually not discriminating enough to provide conclusive results for a common surname.
STRs results may also indicate a likely hapologroup, though this can only be confirmed by specifically testing for that Haplogroups' single nucleotide polymorphisms (SNPs).
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