New technology could reveal which of your genes came from which parent

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This new methodology can help assess people’s disease risk. Image credit: Motortion Films / Shutterstock.com

Did you take your eyes off your mother? Your father’s nose? Well, now there is a technique that can dig deeper than its characteristics and identify which parts of its genome came from which biological parent. The new study, yet to be peer-reviewed, was published in the preprint service bioRxiv.

This type of technology could have greater medical implications, as it could be used in disease risk assessment – ​​when a patient’s risk depends on which gene they inherited from their parents. Another possible use is when doctors need to identify other family members who need to consider screening for the gene.

Normally, most cells in the body have two copies of each autosomal chromosome plus sex chromosomes (XX or XY), these cells are called diploid. The exceptions are sperm or eggs (gametes), which are haploid, meaning they have one copy of each autosomal chromosome and one sex chromosome. In our bodies, we have sets of genes that are so close together that they are unlikely to split during meiosis (which is a type of cell division that reduces the number of chromosomes in a gamete). These sets of genes are called haplotypes and can come exclusively from one of the biological parents.

The team developed the new methodology using DNA sequence data from the genomes of five people. These genomes had already been analyzed previously in previous studies, and the genomes of each biological parent were available and accessible so that the developed methodology could be validated.

All the genomes tested contained 22 pairs of autosomes – the typical number of human non-sex chromosomes. With autosomal pairs, one comes from the biological mother and the other from the biological father. Prior to this research, it was often difficult to determine the parent of origin for these autosomes.

An existing technique called “Strand-seq” was applied to the datasets. Strand-seq is a genome library preparation method that can capture template strands of parental DNA in daughter cells. This technique can be used as a support for other techniques to determine whether an autosome is maternally or paternally inherited without parental sequence data.

So to identify which autosome came from which parent, scientists looked for evidence of epigenetic markers. The type of marker examined was DNA methylation, which is a biological process where methyl groups are added to the DNA molecule. It is important as it can change the activity of the DNA molecule without changing the sequence. DNA methylation patterns can be inherited from biological parents.

DNA methylation has been examined in nearly 200 regions of DNA, and these are well-known sites that can be used to identify parental-specific methylation. These sites were then used as a guide to predict which biological parent was the source of a specific autosome – this indicated that only two or three parent-specific methylation sites were needed to identify the source. The results were confirmed by looking at the genomes of the biological parents.

In the future, this method may become a routine component of genomic analysis.

“We predict that this will improve the diagnosis and management of many genetic diseases,” the authors write in their paper.

[H/T: New Scientist]

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