A genetic technique can identify which parts of your genome came from your biological mother and which parts are from your biological father. The method could be useful in cases where an individual is carrying a disease-associated gene variant by helping to establish which other family members should consider undergoing screening for the gene.
鈥淚t鈥檚 a very, very cool study,鈥� says at the Hebrew University of Jerusalem, who wasn鈥檛 involved in the research. 鈥淪uppose that a person was found to carry a gene variant that increases their risk of a certain cancer. If the parents are not available, how do you know which side of the family to test? You could test both sides, which will take more effort, or you could use this new sequencing method and determine which parent was the carrier, then only test relatives of that parent.鈥�
at the University of British Columbia, Canada, and his colleagues developed the approach using DNA sequence data from the genomes of five people, which had been analysed in previous studies. The researchers also had access to genomes belonging to the biological parents of each of the five people.
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As is typical of humans, each genome tested contained 22 pairs of non-sex chromosomes, called autosomes, with each pair containing one chromosome from the biological mother and one from the biological father.
The team then applied an existing technique called Strand-seq to sort all autosomes into two sets, one from each parent, but this didn鈥檛 establish which parent was which.
To identify whether an autosome came from the biological mother or father, the researchers looked for evidence of a type of epigenetic marker called DNA methylation in around 200 regions of the DNA.
鈥淎bout 200 sites in the genome are methylated only in the paternal or only in the maternal chromosome. These sites are well known, and the parent-specific methylation is robust,鈥� says Carmi.
Using these sites as a guide, Jones and his colleagues were then able to predict which biological parent was the source of a particular autosome. They then confirmed their results by looking at the genomes of the biological parents.
鈥淭he researchers showed that they just need two to three parent-specific methylation sites in order to assign a parental origin,鈥� says Carmi.
The method could also help to trace the relatives of an individual.
鈥淲here I find the method more interesting is in the context of genealogy, where individuals would like to learn about their ancestry or relatives. Here, it isn鈥檛 uncommon that the parents are no longer available, either because they already died or because of adoption. In these cases, the new method will provide the only way to tell from which side of the family a relative [found through genetic testing] came from,鈥� says Carmi.
However, clinical application of the technique will be limited by the high cost of the equipment and can only be carried out by people with the relevant expertise.
鈥淭he method could be very expensive 鈥� I think thousands of dollars in the best case,鈥� says Carmi.
Jones and his colleagues didn鈥檛 respond to a request to discuss their work.
Reference: bioRxiv,
