[New analytic methods provide answers regarding chromosome aberrations in 1-2 days]

During the last decade, new tools have been made available to clinical genetics laboratories through the technologies developed for gene scanning, sequencing, detection of short tandem repeats (STRs) and single nucleotide polymorphisms (SNPs). Two methods (interphase fluorescence in situ hybridization, FISH, and quantitative fluorescence PCR, QF-PCR assay) have been introduced recently for the rapid prenatal diagnosis of numerical chromosome abnormalities within 1-2 days after sample collections, thus obviating the 7-14 days delay needed for cell culture associated with conventional chromosome analysis. Most commonly, probes or STRs specific for chromosomes 13, 18, 21, X and Y are used as, depending on the indications for invasive tests, numerical abnormalities involving these chromosomes account for the vast majority of the chromosome aberrations identified prenatally. The advantage of QF-PCR over inter-phase FISH is that the former is considered substantially more cost-effective, in particular when larger sample numbers are processed.