Leica Biosystems HER2 FISH System - 30 Test - Manual (Page 10)

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Leica Biosystems Leica HER2 FISH System - 30 Test Instructions for Use TA9217 EN-CE-Rev_D 08/04/2013
Recommended Method for LSI HER2 to CEP17 Ratio Determination
To determine the LSI HER2 to CEP17 ratio, use the following method:
1. Record and determine the number of LSI HER2 and CEP17 signals in 20 nuclei (see
Figure 2 Leica HER2 FISH System - 30 Test score sheet below).
2. Total all of the LSI HER2 signals. This represents the total LSI HER2 signals for the count,
e.g. 143.
3. Total all of the CEP17 signals. This represents the total CEP17 signals for the count,
e.g. 48.
4. To calculate the final result, use the following calculation:
Total LSI HER2 signals divided by Total CEP17 signals,
e.g. 143/48 equals a ratio of 2.98, which is positive for HER2 amplification.
Important Note: If the LSI HER2 to CEP17 ratio is equivocal (1.80 - 2.20), count an
additional 20 nuclei and recalculate the ratio.
Results should be reported as follows:
1. If the ratio is <2, HER2 gene amplification was not observed
2. If the ratio is ≥2, HER2 gene amplification was observed
Important Note: A ratio at or near the cut-off (1.80 - 2.20) should be interpreted with
caution, as described above.