Chromosomal Microarray versus Karyotyping for Prenatal Diagnosis

This large, systematic study of prenatal diagnosis shows that chromosomal microarray analysis provided additional, clinically significant cytogenetic information as compared with karyotyping but did not identify triploidies and balanced translocations. The development of array-based molecular cytogenetic techniques has improved the detection of small genomic deletions and duplications (called copy-number variants) that are not routinely seen on karyotyping, the standard cytogenetic analysis performed. Copy-number variants result in a variation from the expected number of copies of a segment of DNA (i.e., the number in a normal genome). Copy-number variants can be either benign or pathogenic, depending on their location and genetic content. They are identified with the use of chromosomal microarray analysis in which a test sample of DNA from the patient is compared directly or indirectly with a reference (normal) . . .