Detecting microscopic differences of twins and eggs

In the era of modern genetic technology, police can often identify a suspect through a small hair or blood droplet collected at the scene. However, their techniques may fail if the suspect has siblings with eggs.

Find out the tiny difference of twins and eggs

Twins and eggs have 100% identical genes. This means, until now, experts still can't determine which test sample originated from the same twins and eggs.

In 2013, two identical twins Mohammed and Aftab Asghar, 22, were charged with rape of a 17-year-old girl in Berkshire, because police were unsure of the DNA evidence of any of them. Mohammed was eventually convicted, and Aftab was determined to be unjust due to the mobile phone evidence that he was not present at the crime scene.

However, in some other cases, the authorities even have to cancel the prosecution, instead of risking convicting the wrong person in the twins. For example, in 2011, US prosecutors abolished allegations of murder against Orlando Nembhard, 19, because he could not prove he or his twin brother, Brandon Nembhard, shot a teenager. outside the nightclub in Arizona.

However, this problem has just been solved by a group of British researchers. Researchers at the University of Huddersfield claimed to have created a technique that could distinguish the genetic characteristics of twin brothers and sisters . Their technique heated DNA until its links were broken, helping to identify microscopic differences between the twins.

The team explained, the same twins born with the same genes, by forming the same fertilized egg, divided into two embryos. However, when you grow up and get older, different life experiences , such as smoking habits, sun exposure, chemicals, diets, . create a difference. especially in many hydrogen bonds inside their DNA.

The new DNA heating technique, called HRMA , helped uncover these subtle differences in the DNA of twin brothers and sisters. The technique relies on the concept of DNA methylation - the molecular mechanism that turns on / off many genes.

Environmental factors have changed the methylation status of DNA, changing the way it works. For example, an identical twins do outdoor work, while the other person does paper work, their DNA methylation characteristics are also slightly different. Essentially, the methylation process changes the amount of hydrogen bonding.

This breakthrough has been found to help eliminate major obstacles to identifying suspects, which often occur when one of the identical brothers and sisters causes crimes.

However, Dr. Graham Williams, a member of the British research group, admitted, their techniques still have some limitations. For example, if the same egg twins are raised in very similar environments, they may not develop sufficient methylation differences. In addition, the technique also requires a relatively large DNA sample, which may not always exist in the crime scene.