The National Institute of Standards and Technology (NIST), in a recent paper, has suggested guidelines for improving the current system of genetic genealogy testing. According to them, the guidelines will increase the accuracy and reliability of test results.
Genetic genealogy is a lesser known, but rapidly growing application of DNA profiling in which a person's paternal ancestry is traced for forensic examination of evidence recovered at a crime scene.
The laboratories performing this testing often differ in their results, making data comparison between labs difficult and casting doubt on reported genetic matches.
And the researchers are hopeful that the suggestions would help making genealogy testing more accurate and reliable.
A man's paternal lineage can be traced using the DNA on his Y chromosome (Y-DNA), which passes from father to his son.
Genetic genealogy works by studying the sequences of repeating nucleotide (the base components of DNA) patterns on the Y chromosome known as short tandem repeats (STRs).
Each STR is considered a separate marker for potential genetic matching because the number of times it is repeated will be the same for related males.
For instance, a person may have one STR sequence that repeats 12 times, another 11 times, a third 17 times and so on. If another male has a Y chromosome with a high percentage of the same STRs, it is considered likely that they share a common ancestor.
Counting the number of repeats accurately is a tricky task and the source of much of the error in genetic genealogy tests, causing genealogists to make incorrect matches or miss family connections altogether.
In the paper, the NIST researchers have explained the basis for the differing interpretations and have offered a solution using the agency's certified reference material for human Y-chromosome DNA profiling (Standard Reference Material 2395), a collection of Y-STR markers that can serve as a means for genetic labs to calibrate their testing equipment.
The researchers "strongly encourage [SRM 2395's] use to enable compatible and calibrated measurements to be made between different Y-STR testing laboratories."
The paper is published in the Journal of Genetic Genealogy.