G-BANDED KARYOTYPING
WHAT IS KARYOTYPING?
A karyogram is the pictorial alignment of the 22 pairs of homologous autosomes from one metaphase cell, sequentially numbered from 1 to 22 (largest to smallest, one exception is that chromosome 21 is shorter than chromosome 22) by their unique band patterns, and the two sex chromosomes, XX (female) or XY (male). Alignment of the normal homologues is centered with the centromere so that the bands can be compared equally between the two arms of the homologous pair1,2.
A karyotype is the unique language of cytogenetics that translates what is analytically observed from multiple cells of a specimen into a universally understood string of alpha-numeric symbols. It is a way for cytogeneticists to explain the chromosomal makeup, normal or abnormal, constitutional or acquired1,2.
G-banding is the technique used to produce thin, alternating bands along the length of the entire chromosome that create unique patterns on each homologous set and allows for their identification. Giemsa or Leishman stain are often used in this technique1.
WiCell's chromosome analysis is optimized for pluripotent stem cells. Our analysis are reviewed by an American Board of Medical Genetics and Genomics (ABMGG) board certified or board eligible director, with results available in 7-10 days.
WHAT IT DETECTS:
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Microscopic genomic abnormalities (>5-10 Mb)
- Inversions
- Duplications/deletions
- Balanced and unbalanced translocations
- Aneuploidies
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>10% mosaicism (for example: cultures where >1 of 10 cells are trisomy 12)
WHAT IT DOESN'T DETECT:
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Submicroscopic genomic abnormalities (<5Mb)
WHEN TO USE:
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As a baseline genomic screen
- At derivation of cell lines
- At the start of experimental protocols
- To assess and monitor genomic stability (ex. every 5-10 passages of cell culture)
- At conclusion of experiments (prior to publication)
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For cell line banking when publication-quality karyotypes are needed
INTERPRETING YOUR RESULTS:
REFERENCES:
2. McGowan-Jordan, J., Simons, A., & Schmid, M., (Eds.) (2016). An International System for Human Cytogenomic Nomenclature (2016). Basel, Switzerland: S. Karger Publishing.
