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The Possibilities of Medicine to Detect Genetic Disorders through Mother's Blood Were Presented at MU-Varna

The new possibilities of modern medicine for early detection of genetic diseases such as Down syndrome, Patau's syndrome, Edward's syndrome during pregnancy and some of the defects related to sex chromosomes through utilization of non-invasive DNA tests were presented at MU - Varna.

Prof. Dr. Lyudmila Angelova - Head of TRS Medical Genetics at the Department of Pediatrics and Medical Genetics at Medical University - Varna and Head of the Laboratory of Medical Genetics at University Hospital “St. Marina” - Varna explained that prophylaxis and in particular, genetic one, is the medicine of the future. The methods for prenatal prophylaxis have their limitations, possibilities and risks. They are in the competence of highly qualified, but very few specialists in our country.

 “Genetic counselling should accompany every step of the cares provided for a pregnant woman,” advises Prof. Angelova and explains the differences between screening and diagnosis. “These prophylactic methods are divided into non-invasive and invasive. Non-invasive are biochemical screening, ultrasound diagnosis of fetal anomalies, and non-invasive prenatal tests of fetal DNA in mother’s blood. They are available throughout the different periods of pregnancy, they have different characteristics, but these are screening approaches, not diagnostic. They are characterized with negligible risk, there is no risk involved in them, they can be offered on a large scale, but they are of low sensitivity. Prenatal tests of fetal DNA in mother’s blood are the most sensitive. If an anomaly is detected, even with 99% sensitivity of the test, it has to be validated by a second invasive diagnostic method before a pregnancy is interrupted,” said Prof. Dr. Angelova. According to her, the invasive methods of Chorion biopsy, Amniocentesis and Cordocentesis have one hundred percent sensitivity, but they pose a risk to the fetus.

“In prenatal prophylaxis we follow criteria, we take into consideration whether we have a serious illness or not, whether there is adequate treatment. It is usually severe, usually incurable, the genetic risk is different, we need to know whether the family is ready to interrupt the pregnancy, whether there are prenatal tests,” explained Prof. Dr. Angelova. She underlined that under diagnosis we should understand proving or rejecting a disease, not screening of high-risk pregnancies. “The family is always searching for 100% guarantees, anyway, there are no such guarantees due to a number of reasons. There is no genetic test that is 100 % accurate. It may not detect all mutations, but only selected ones, characteristic of a population of mutations. Genetic tests detect a mutation, but they do not reveal the degree and severity of the disease,” said the specialist.

PrenaTest is the first non-invasive prenatal test on the territory of Bulgaria and Europe and is performed only through mother’s venous blood. The test can be done after the 9 week of gestation, and the results are evident within 7 working days. The analyzes are carried out at LifeCodexx Laboratory (Konstanz, Germany). PrenaTest is also applicable in cases of bigeminal pregnancy or after assisted reproduction. “More than 80 000 analyzes have been carried out globally and more than 2 000 in Bulgaria,” explains Silvia Kostova, Product Manager of PrenaTest.

 “The advantages of non-invasive prenatal tests are the absence of any kind of risk to the fetus, 98-99% precision of autosomal aneuploidy analysis, a much earlier test period, and testing the genetic material of the fetus itself. Biochemical screening of biochemical markers of the fetus is carried out in the 1st and 2nd trimesters of pregnancy, with a sensitivity of between 70 and 90%, and the result is in the form of a probability calculation that categorizes high-risk pregnancies to be directed to the well-known invasive methods of Amniocentesis and Chorion biopsy. They pose a risk of complications and can only be performed in a limited number of hospitals, which also creates additional inconveniences for pregnant women,” Silvia Kostova added.
Silvena Hristova, chairperson of "Life with Down Syndrome" Foundation and a mother of a three - year old child with Down syndrome told her personal story:
"We had consultations with 7 specialists during the pregnancy; we went through early and late biochemical screening, integrated risk, echography. No specialist had ever told us that our child was likely to be born with Down syndrome, no one had advised us to do a prenatal test, in which the results were much more accurate. We were certain that our child was well. However, Mikaela was born with Down syndrome. I am already sure that there is no 100% in medicine! There are cases in families where the first child has Down syndrome, and during the second pregnancy they lose a healthy child after amniocentesis. Therefore, tests such as PrenaTest are an important option for the families. In Bulgaria the society refuses to accept our children because there is no adequate information. Provided we work hard with these children, the results can be positive.”
The meeting was attended by Maria Stoyanova, who is the 2 000th patient of PrenaTest in Bulgaria. She said that the genetic test was recommended to her by a doctor, who was monitoring her pregnancy because of her age. “He strongly recommended to me to do a non-invasive DNA test, not biochemical screening or an invasive method,” explained Maria.