Conventional karyotyping +/- FISH is used for:
Investigation of congenital anomalies;
delayed puberty; infertility;
recurrent spontaneous abortion (test both parents); and
microdeletion syndromes,see also Fluorescence in situ hybridisation.
Microarray testing is used to investigate patients with developmental delay/intellectual disability and/or multiple congenital anomalies.
Microarray testing has a higher resolution for gains/losses of genetic material than conventional karyotype, but will not detect balanced chromosomal rearrangements, Microarray testing may not detect mosaic gains or losses of genetic material.
Microarray testing is rebated by Medicare only for investigation of developmental delay/intellectual disability OR autistic spectrum disorder OR patients with two or more congenital abnormalities. Note that karyotype and microarray testing will not be rebated by Medicare if requested on the same test episode.
Karyotype or microarray studies should be performed on the affected individual and sometimes family members may also require investigation.
Molecular genetics has now replaced cytogenetics for the diagnosis of Fragile X syndrome.