Science Talk: Cytogenetics: What is it and what is it used for?

Cytogenetic techniques include cell culture, chromosome preparation, karyotype analysis of G-banded chromosomes (and other chromosome banding techniques) as well as molecular cytogenetics including fluorescence *in situ* hybridization (FISH) and chromosomal microarray by comparative genomic hybridization (CGH).
There is a relationship between chromosome gains, losses, or alterations to chromosome structure and a number of human diseases and genetic conditions such as Down Syndrome, a phenotype caused by the presence of an extra chromosome 21 (Trisomy 21).
Clinical cytogenetics includes evaluation of newborns and children with birth defects, study of individuals experiencing repeated pregnancy loss or unexplained infertility, evaluation of prenatal samples for chromosomal changes, and detection of cancer-associated chromosomal changes in patients with solid tumors and hematologic neoplasms.
The same techniques are used in cytogenetic research for studies on chromosome evolution and speciation.