A new chromosome study may lead to individualized counseling for pregnant women, claims a research team.
Fetuses with a so-called new balanced chromosome aberration have a higher risk of developing brain diseases such as autism and mental retardation. According to a study by the University of Copenhagen, the risk of fetuses with such aberrations is 20 percent.
These chromosomal aberrations occur in one out of 2,000 pregnant women in the fetus. So far, when such a deviation was found, the doctors of the pregnant woman said that the risk of the fetus developing congenital malformations is 6-9 percent.
"We identified all people who were fetuses In Denmark, such a chromosome aberration was diagnosed and we find that they have developed a disease more often: The previous study, which showed a risk of 6-9%, examined mainly congenital malformations and did not include neurocognitive disorders such as autism and mental retardation that often occurs later, so we were unaware of the magnitude of the overall risk, "said one of the authors of the study, Iben Bache.
We call these aberrations balanced chromosomal rearrangements because all the genetic material is still there. There is no loss or gain in genetic material. The problem is that parts of the genetic material have been exchanged, and that could have caused the disruption of an important gene, "said Bache.
The study was the largest systematic study of these rare chromosome aberrations in fetuses and was also evaluated using the methods These chromosomal abnormalities are diagnosed by chorionic villus sampling or amniocentesis using classical chromosome analysis, whereby the genetic material is examined microscopically.
This method has been used for 40 years and is still the method used in most pregnancies However, in Danish hospitals, this method is increasingly being replaced by another method, the chromosomal microarray, which tests exclusively for loss and gain of the genetic material.
Chromosomal microarray can therefore balance the rare ones studied here Do not discover aberrations. In contrast, the study shows that modern genome sequencing is in most cases not only able to detect these balanced chromosomal aberrations, but also whether genes have been damaged.
The researchers carefully examined the Danish health records to find all de novo balanced chromosomal aberrations since 1
In addition, the researchers found that the New Genome Sequencing techniques are much better than any other techniques to assess the health effect of a balanced chromosome aberration. This is the conclusion of almost identical assessments made by two independent research groups, including a group from Harvard Medical School.
"We did not know which analyzes would be used to distinguish the healthy fetuses from those that would evolve later Our study shows that by using the new sequencing technologies we can actually discriminate in a number of cases severely affect the diagnosis and counseling of pregnant women who carry fetuses with this specific type of chromosome aberration in the future, "said Bache.
The study appears in the American Journal of Human Genetics.
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