What is array CGH

Array comparative genomic hybridisation (CGH), a new cytogenetic technology, is a new diagnostic tool for genetic disorders. A 2-year-old girl was seen in clinic because of concerns regarding her development. Her parents say that she has always been a bit floppy and had difficulties feeding as a baby. She is not yet walking, but bottom-shuffles. She has no recognisable words. In clinic, she has a happy disposition and is hypotonic. The child had previously had a karyotype which was normal. Array CGH revealed a microdeletion of the long arm of chromosome 17 (17q21.31) (figure 1). This is a microdeletion syndrome which is reminiscent of Angelman Syndrome. Figure 1 Array plot showing a microdeletion at 17q21.31, not visible on conventional karyotype. For many years, chromosome imbalance has been tested by karyotyping. Karyotyping is only able to detect relatively large abnormalities, …