Cytogenetics

Cytogenetics looks at the chromosomes themselves — how many there are and whether their structure is intact. The sample is cultured so that cells divide, then arrested, dropped onto slides and banded, and each chromosome is photographed and arranged into a karyotype.

Missing, extra or rearranged chromosomes become visible on that karyotype, which is why this is the department behind recurrent-miscarriage work-ups, developmental delay in children, infertility studies and part of the classification of blood cancers.