Recently completed, the new technique of molecular genetics called Prenatal BoBs allows to identify some of the most frequent forms of a part of congenital disease linked to the presence of submicroscopic modifications of DNA that cannot be detected through the traditional cytogenetic examination. This technique, by FISH in the liquid phase, allows a multiple detection of aneuploidies of chromosomes 13,18,21, X and Y and 9 microdeletions associated with genetic syndromes.
It is a series of 9 complex anomalies (syndromes), associated with mental retardation or malformations, which are due to the loss of a small part of the DNA that constitutes the chromosomes (microdeletions), and that have globally a frequency in the order of just less than 1 in 1000.
HOW TO PERFORM THE PRENATAL BOBS?
Because the examination is an important and useful complement to the traditional cytogenetic examination, carried out through an invasive survey (amniocentesis or chorionic villus sampling) offering a high level of security against a series of very strict conditions, which in most cases are not identified in the prenatal period and that at most may be suspected late for the detection of abnormal ultrasound data, but non-specific, such as growth restriction or structural abnormalities.
This examination is particularly suitable for all couples at risk for these abnormalities (i.e., because they have a sick child or because the previous ultrasound showed a picture of characteristic malformations in the fetus).
However the Prenatal BoBs can be offered to all spouses that perform invasive prenatal diagnosis, due to the high level of precision (the presence of a microdeletion is unambiguously related to a specific syndrome) and to relatively low costs. The examination also has the advantage, which is not secondary, to allow rapid diagnosis of autosomal trisomies (21, 13 and 18), similarly to the interphase FISH and/or QF- PCR.
WHICH DISEASES CAN BE DETECTED BY THE PRENATAL BOBS?
The Prenatal BoBs was developed to detect aneuploidy of chromosomes 13, 18, 21, X and Y in addition to the deletions and duplications in 9 common regions responsible for syndromes.
The nine diseases detectable with the Prenatal BoBs are as follows: George syndrome
Cri du Chat syndrome
WHEN MAY I PERFORM THE PRENATAL BOBS?
The Prenatal BOBs is performed concurrently with the invasive diagnosis examination (amniocentesis and chorionic villus sampling), thus in the case of chorionic villus samplingit's performed around the 11-13th week and in the case of amniocentesis around the 15-17th week.