This week we will be taking a break from Dr, Cody's FAQ videos to provide one answer to the pertinent question: "Why did this happen to me?"
In her response, Dr. Cody states:
"This is a question commonly asked which I have addressed on a number of occasions. Quite understandably, parents want to know if they inadvertently did something or were exposed to something that caused their child to have a chromosome 18 condition. But the reality is that chromosome deletions, duplications and translocation are something that happen as unprovoked errors during cell division. There are no data indicating that any environmental exposure of the parents can cause chromosome abnormalities in their children. But the human studies to date included small numbers of people and used very limited DNA testing techniques. Their findings were therefore suggestive but not conclusive.
One type of environmental exposure that has been a major concern is that if radiation exposure. A recently published paper in the journal Science addressed those concerns. The authors investigated the transgenerational effects of the 1986 Ukrainian Chernobyl Nuclear Power Plant disastrous meltdown that released large amounts of ionizing radiation into the environment. This is the first large scale whole genome sequencing study that measured the effects of this nuclear accident on the offspring of those exposed. The authors report on the evaluation of 130 children (born between 1987 and 2002) whose parents were either evacuees from the immediate area near the power plant or were clean-up workers in the plant after the meltdown. Whole genome sequencing was perform on the children as well as both parents to determine if the children had acquired an excess of new DNA changes not found in the parents. Had the researchers found an excess number of DNA changes in the children it would have meant that the germ cells (sperm or egg cells) in the parents had sustained DNA damage.
Typically in an unexposed population there are about 50 to 100 new mutations per individual not found in their parents. As pointed out at the beginning of this article, mistakes in DNA replication leading to cell division just happen. Considering that 3.2 billion of the DNA building blocks need to be copied in each cell in order to divide in the two daughter cells, this rate of mistakes (new mutations) is astonishingly small. In this study, the investigators did not find any increase in the number of new mutations or DNA variations in the children of the radiation exposed parents. These data support the observation that the germ cells in the human body have evolved to be well protected from external sources of potential DNA damage."
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