The Fluorescence in Situ Hybridization (FISH) Microdeletion Syndromes test screens for microdeletion syndromes resulting from chromosomal deletions smaller than five megabases. These syndromes are associated with multiple congenital anomalies and developmental delays. Fluorescence in situ hybridization detects cryptic chromosomal rearrangements compared to traditional chromosome analysis. The test confirms screening results, screens family members, and performs prenatal diagnoses.