Localization chromatid breaks in Fanconi's anemia, using three consecutive stains.

The location of 339 break points was analyzed in three patients with Fanconi's anemia, using three consecutive stains: ordinary Giemsa, Q-banding, and R-banding. Almost all the breaks seem to take place in the Q bands, using R-banding, and in the R bands, using Q-banding. A very important artifact, varying according to the method used, is thus demonstrated. In fact, the breaks take place in the interbands, between R and Q bands. The breaks were also localized in relation to sister chromatid exchanges (SCEs), seen after BUDR treatment. There is a clear excess of breaks at place of SCE (29%). This may indicate a possible correlation between breaks and SCEs.