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Cytogenetics is a subcategory of genetics that specifically studies chromosomes and their structures. "Trained cytogeneticists examine the number, shape, and staining pattern of these structures using special technologies. In this way, they can detect extra chromosomes, missing chromosomes, missing or extra pieces of chromosomes, or rearranged chromosomes."[1] Some diseases occur as the result of these chromosomal anomalies; for example, amplification of a particular gene in breast cancer or translocation of part of a chromosome in chronic myelogenous leukemia may be spotted with cytogenetic techniques.[1]
The cytogenetics laboratory depends on several analytical techniques to make these sorts of genetic discoveries in a patient. Methods include chromosome analysis or karyotyping, fluorescence in situ hybridization (FISH), and microarray-based assays such as comparative genomic hybridization.[1][2][3] Karyotyping involves the separation of whole chromosomes from the nuclei of cells that have been stained with special dyes, cutting and arranging the resulting imagery of those chromosomes, and examining the results. FISH uses special "probes" that fluoresce gene segments of chromosomes. The position and number of the fluoresced gene segments is then analyzed for abnormalities.[1] And the comparative genomic hybridization assay uses a complicated process of using a "competitive" form of FISH that compares two DNA sources, which are denatured so they are single-stranded, and hybridizes the two samples in a 1:1 ratio to a normal metaphase spread of chromosomes.[4]
Like a normal medical diagnostic laboratory, the cytogenetics laboratory must follow a set of good practices, many of which are similar to the medical diagnostic lab. However, additional considerations to good practice specific to the cytogenetics laboratory are typically required, particularly in being assessed for accreditation. In Australia, for example, the National Pathology Accreditation Advisory Council (NPAAC) makes recommendations on the accreditation of laboratories providing cytogenetic services.[5] The College of American Pathologists (CAP) does something similar with its Cytogenetics Checklist for its CAP Accreditation Program.[6]
References
- ↑ 1.0 1.1 1.2 1.3 Cite error: Invalid
<ref>tag; no text was provided for refs namedAACCGenetic19 - ↑ "Cytogenetics Laboratory". Departments and Centers: Laboratory Medicine and Pathology. Mayo Clinic. https://www.mayoclinic.org/departments-centers/laboratory-medicine-pathology/overview/specialty-groups/laboratory-genetics/cytogenetics-laboratory. Retrieved 18 November 2021.
- ↑ "Cytogenetics Lab Tests". Cytogenetics Lab. Yale School of Medicine. https://medicine.yale.edu/lab/cytogenetics/testing/. Retrieved 18 November 2021.
- ↑ Weiss, M.M.; Hermsen, M.A.; Meijer, G.A. et al. (1999). "Comparative genomic hybridization". Molecular Pathology 52 (5): 243–51. doi:10.1136/mp.52.5.243. PMC PMC395705. PMID 10748872. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC395705.
- ↑ National Pathology Accreditation Advisory Council (2013) (PDF). Requirements for Cytogenetic Testing, Third Edition (3rd ed.). Commonwealth of Australia. ISBN 9781742419572. https://www1.health.gov.au/internet/main/publishing.nsf/Content/76FFC342EA4F4CCBCA257BF0001D7A2A/$File/V0.22%20Cytogenetics.pdf. Retrieved 18 November 2021.
- ↑ College of American Pathologists (21 August 2017). "Cytogenetics Checklist" (PDF). https://elss.cap.org/elss/ShowProperty?nodePath=/UCMCON/Contribution%20Folders/DctmContent/education/OnlineCourseContent/2017/LAP-TLTM/checklists/cl-cyg.pdf. Retrieved 18 November 2021.
