Microdeletion syndrome

A microdeletion syndrome is a syndrome caused by a chromosomal deletion smaller than five million base pairs that spans several genes at once. These deletions are too small for standard karyotyping to detect and instead require specialized molecular techniques such as fluorescence in situ hybridization, or FISH, to identify. Because a microdeletion removes multiple neighboring genes together, the resulting condition produces a characteristic pattern of symptoms that depends on which genes are lost and what those genes normally do, and the specific features differ across the many distinct microdeletion syndromes that have been identified.