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The development of conventional cytogenetic techniques in the 50’s leaded to a rapid increase of the knowledge on the etiology of malformation syndromes, being chromosomal anomalies reported as the most common genetic condition in humans (Pena, 1998). Around 2-3% of newborns may have congenital malformations, and from those, just 20% have an established etiology (genetic or environmental), being 80% of these multifactorial or unknown (Stevenson & Hall, 2006). But this is only the tip of the iceberg, as probably half of the human concepts may have some kind of chromosomal defect (A. Boue & J. Boue, 1973), indicating that cytogenetic analysis is fundamental for the investigation of these cases. Since the 70’s, prenatal diagnosis for detecting cytogenetic abnormalities has become a routine procedure in many countries, and an important tool for the prevention of birth of handicapped children (A. Milunsky & J. Milunsky, 1998). Cytogenetic analysis is an important component of invasive prenatal diagnosis as chromosomal abnormalities are detected in about 1 in 200 newborns and constitute a major cause of mental retardation and congenital malformations (Shaffer & Lupski, 2000). Microscopic chromosome analysis of cultured cells has been regarded as the gold standard method for prenatal diagnosis, since its first application to prenatal testing in 1966 by Steele and Breg (Steele & Breg, 1966) and the routine use of chromosome banding analysis in 1970s. Karyotyping has proved to be highly reliable for diagnosis of numerical chromosome abnormalities and structural rearrangements in fetal cells obtained invasively by either amniocentesis in the second trimester of pregnancy, or chorionic villus sampling (CVS) in the first trimester, since the early 1980s. The diagnostic accuracy of karyotyping fetal cells from cultured amniotic fluid (AF) has been found to be 99.4%-99.8%, and that of CVS 97.5-99.6%. However, the main limitation of karyotyping is the requirement of a cell culture, resulting in a period of 10-14 days for obtaining the final results (Bui, 2007). Furthermore, the success of cell culture depends on many factors: very good laboratory conditions for tissue culture, technician’s experience, and satisfactory cell growth with good quality of metaphases. Unfortunately, due to failure in one of these steps the whole process becomes jeopardized.

The Contribution of Molecular Techniques in Prenatal Diagnosis and Post mortem Fetus with Multiple Malformation