2023-11-23 15:44:02
The amniocentesis is a test that removes amniotic fluid, which surrounds and protects the baby during pregnancy, and cells from the uterus to obtain information about the baby’s health; However, it has associated risks. But now, thanks to a non-invasive genetic test, developed by a team of researchers from the Hospital General de Massachusetts (MGH), el Hospital Brigham and Women’s (BWH) and the Broad Institute of MIT and Harvard (US), it is possible to test the blood of pregnant people to study all fetal genes safely.
So far, the test has been evaluated on blood samples from 51 pregnant people and it has been seen that the test could capture variants inherited from the mother, as well as new variants that were not present in the mother and were associated with prenatal diagnoses. The results are published in ‘The New England Journal of Medicine‘.
“The study suggests that it is feasible to detect the majority of genes in the fetal genome through a blood test without the need for an invasive procedure such as amniocentesis,” explains the lead author. Michael E. Talkowski.
Non-invasive prenatal tests can detect, through a blood test of a pregnant person, important changes in the fetal chromosomes, such as an extra copy of the chromosome 21, known as Down syndrome (trisomy 21); the gain or loss of entire copies of other chromosomes; the presence and number of X and Y sex chromosomes (which indicate the sex of the fetus) and, more recently, a small number of variants that are relevant to some fetal conditions.
However, many prenatal genetic diagnoses require determining individual nucleotide changes in the genome’s protein-coding sequence, known as “exome».
Currently, exome detection requires genetic testing with an invasive medical procedure such as amniocentesis, which involves significant cost and carries some inherent risks to the mother and fetus.
This test now offers the ability to discover and interpret variants in the fetal exome from DNA circulating in the mother’s blood.
The team calls the method non-invasive fetal sequencing (NIFS).
This high-resolution NIFS approach allowed the research team to examine the exome, discover sequence changes, and distinguish potentially pathogenic variants from likely benign variants inherited from the mother.
The test offers the ability to discover and interpret variants in the fetal exome from DNA circulating in the mother’s blood
They tested their NIFS approach on 51 pregnancies that spanned all three trimesters.
The NIFS screening method used a maternal blood draw without the need for separate genetic testing of the mother or father.
The results showed that the method was very sensitive in discovering single-base DNA changes and small insertions and deletions that were present in the fetal genome but not in the maternal genome, regardless of the amount of fetal DNA detected.
“In our analysis we were able to accurately discover and predict fetal sequence variants from the NIFS approach with >99% sensitivity from the raw data and >90% sensitivity after filtering using our analysis methods,” notes the co-lead author Harrison Brand.
The implications are important, especially for pregnancies in which a fetal anomaly is suspected.
In 14 pregnancies referred for current standard of care genetic testing that were also evaluated with the NIFS approach, The test detected all clinically relevant variants that were reported from invasive testing in the same individuals.
The authors performed this initial test on 51 pregnancies, but the findings suggest the test could be performed on many samples. “The clinical implications of this research are important, especially for pregnancies in which a fetal anomaly is suspected by ultrasound and invasive testing is indicated,” says co-senior author Kathryn Gray.
“It has long been known that fetal sequence variants can be obtained from cell-free fetal DNA, and exome sequencing is already part of the standard of care, but currently requires an invasive procedure,” adds Talkowski. “Our results suggest that non-invasive sequencing can probably capture the same genetic information from the fetal exome that is already obtained in standard treatment, but only from a blood test, without the need for invasive procedures.”
The team emphasizes that this is not currently a clinical trial available to women who want it and that these first studies must be replicated in much larger samples.
#prenatal #genetic #test #retire #amniocentesis