Mother and baby home investigations include DNA analysis using maternal genetic material

The investigation into the Tuam Mother and Baby Home in County Galway will include DNA analysis using genetic material from the maternal line only.

The investigation, overseen by Daniel McSweeney, director of the Authorized Intervention Unit, will include, where possible, comparing the genetic material in the remains with references from people believed to be related to them , to identify the bodies buried beneath Tiam.

Forensic Science Ireland (FSI), the national laboratory responsible for the examination of DNA material, is currently investigating and its research tools will include the examination of mitochondrial DNA (mDNA).

Although it is commonly believed that humans only have DNA contained in the nucleus (genome) of their cell, they actually possess two different sets of DNA – the material in the nucleus that is essential for human growth, development and many of its characteristics, and a piece within the mitochondria Small, independent pieces of genetic material, mitochondria are units that play a key role in energy production within each cell. While a person’s genome contains material from both sperm and eggs, the small amount of genetic material within each cell’s mitochondria comes only from the egg.

Dr. Geraldine O’Donnell, director of genetics at FSI, said the mitochondrial DNA analysis uses DNA from the tiny energy factories inside the mitochondria of all human cells. Mitochondrial DNA may be more abundant and useful in situations where biological material is limited, such as when cells have been damaged by environmental exposure, elements such as heat, light or water that can damage DNA strands.

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Mitochondrial DNA is inherited by the child from the mother, so all maternal relatives in the family will share the same mitochondrial DNA. This genetic pattern, coupled with the useful evidence provided from decomposed human remains, makes mitochondrial DNA analysis very important in family identification programs of mothers and infants.

The state lab will use next-generation sequencing technology when examining mDNA materials, a new breakthrough in its suite of tools. It will also use technology based on DNA sequencing, which involves detecting tiny variations in DNA strands called single nucleotide polymorphisms, which may also have advantages in the case of Tuam’s case.

The existence of separate DNA material within mitochondria results from an evolutionary event about 2 billion years ago that gave rise to the complex (eukaryotic) cells found in all animals, plants, fungi and even some single-celled animals, but not in bacteria But no.

Unlike eukaryotic cells, bacteria do not have a nucleus within the membrane and no other organelles outside the nucleus. Scientists believe that mitochondria are the evolutionary descendants of bacteria that were infected or eaten by single-celled organisms about two billion years ago, an event that had a huge impact on life on Earth.

Everything in your cell is important, but [mitochondria] Professor Dan Bradley, professor of genetics at Trinity College Dublin, said they were vital because they produced energy. Map of the origins of future residential population changes.

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In deep evolution, initially, you have a cell, a mitochondrion is a bacterium that gets swallowed up into the cell by its own chromosomes and then progresses over time, so eukaryotic cells, more complex cells like ours, They have remnants of other cells that are engulfed and become mitochondria. Therefore, it is a cell within a cell. Originally it was a bacterium, but now it is not a bacterium. It evolved from phagocytosis of bacteria.

Over time, he says, engulfed bacteria lose elements of their chromosomes, and the parts that are no longer useful degrade or migrate into the host cell’s DNA. Therefore, mitochondrial elements are greatly reduced, mainly related to energy metabolism.

He said that everything that still exists in evolution is there because it worked so well, and the stuff that didn’t work no longer exists. But there is no doubt that phagocytosis of bacteria into mitochondria found in all complex cells was a major stepping stone in the evolution of complex life.

The ability to examine DNA material from different sources and find evidence of family links between different DNA samples used to take a lot of time and a lot of money, but can now be done in a few afternoons instead of years, and for just a few hundred euros . Driven by biomedical science, so-called next-generation sequencing has been advancing. Bradley explained that the system works by looking at the genome, which is made up of base pairs, and looking for locations on the segment or code where one of the two possible codes or letters can be found.

The genome is like a giant book, and within that book, within sentences, there are different letters. You have your own unique set of sentences. We’re not that different, but we differ at these points in our genome. One in every thousand letters is different, but that’s a lot of information. There are three billion base pairs, three billion letters, so there’s a lot of diversity.

Since half the genome comes from the mother and half from the father, comparing samples can link cousins ​​who are connected through either mother or father. This is not the case with mDNA.You can only get this from your mother, which means that all people who are maternally related, such as brothers and sisters, have the same [mDNA]if your mother’s sister had children, you would have the same children [mDNA] Just as they do too. So, it’s a special relationship, and it’s good at finding that.

Because mDNA is passed down through the maternal line, it cannot connect you to your father, your father’s father, or his brother, so it has its limitations. This is good for the mother-son relationship. But the entire genome can locate all relationships, down to a certain distance, such as fourth or fifth cousins.