DDx – dim signal

· Denaturation of specimen slide inadequate

· Ensure temp of denaturation solution is appropriate

· Increase denaturation temp

· Increase denaturation time

· Aging of slides was improper

· Age for 24 hours at ambient temperature before performing FISH

· Slides not thoroughly dry prior to immersion in denaturation solution

· Wash too stringent

· Try decreasing the temperature to 70-73 degrees celcius

· Slide was GTG-banded

· Probe not added

· Probe, hybridization buffer, or probe mixture were not mixed well prior to use

· Probes improperly diluted for hybridization

· Probe not adequately denatured’probe not applied to the slide immediately after probe denaturation

· Probe mix dried too much on the specimen slide

· Probes or specimen slides stored improperly

· Air bubbles were trapped under the coverslip during hybridization

· Probe not sealed well with rubber cement

· Melt temperature too low

· Hybridization time too short

· Counterstain is too bright

· Filter set inappropriate

· Microscope filters are damaged

References:

· Vysis CEP probe insert