CGH Labeling

Technical Support Request Form

Low yield and incorporation.

• Poor labeling often reflects low quality input DNA. This can be due to the presence of contaminants from the purification of genomic DNA and/or the presence of degraded DNA and/or cross-linked DNA isolated from FFPE tissues.
  
  

Poor signal to noise ratio despite good incorporation.

• Low signal can be caused by inappropriate hybridization conditions (too stringent buffer or excessive temperature) or when the hybridization time is too short. High background can be caused by inadequate blocking and/or washing conditions. Excessive amounts of labeled DNA can also result in high background.
  
  

Good DLRs in the CGH analytics QC report, but some oligos show whiskering or significant deviation from the expected log2 ratio.

• We suggest keeping the Cot-1 DNA at 50 μg regardless of the hybridization volume.
  
  

Bright yellow array with reduced magnitude of expected changes.

• This can be due to insufficient Cot-1 DNA, blocking agents or hybridization and washing conditions that are not stringent enough.