Result Format
Cytogenetic reporting follows strict international standards to ensure clarity and reproducibility
ISCN (International System for Human Cytogenomic Nomenclature)
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Structure:
<Total Count>,<Sex>,<Abnormality>[<Cells>]-
Example:
46,XY,t(9;22)(q34;q11.2)[20]
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Example:
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Key Symbols
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+/-: Gain or Loss (e.g.,+21,-7) -
t: Translocation (reciprocal exchange) -
del: Deletion -
inv: Inversion -
der: Derivative (unbalanced product) -
;: Separates chromosomes and breakpoints in translocations
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Mosaicism: Cell lines separated by a slash
/-
Example:
45,X[10]/46,XX[10](Mosaic Turner)
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Example:
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Uncertainty:
?indicates questionable identification (e.g.,?del(5)(q31))
Preliminary Results
- Purpose: Rapid reporting for urgent cases (e.g., APL t(15;17), Newborn Trisomy)
- Method: Usually based on FISH (Interphase) or Direct Harvest (poor quality metaphases) within 24–48 hours
- Disclaimer: Must be clearly labeled “Preliminary” with a warning that final results are pending
- Communication: Critical abnormal prelims are typically telephoned to the provider
- Limitation: A negative prelim FISH does not rule out other defects found later in the full karyotype