MOLECULAR CHARACTERIZATION OF AN UNUSUAL VARIANT OF THE SHORT ARM OF CHROMOSOME-15 BY FISH-TECHNIQUE

One of the most frequent translocations involving the long arm of chro mosome Y with autosomes is with the short arm of chromosome 15. The re gions which are involved in this translocation fluoresce brightly, are highly heteromorphic and thus escape detection. Therefore, these abno rmalities could not be fully characterized, especially in cases where parents are not available or paternity is disputed. Results from the e mployment of the selective staining techniques DA/DAPI and Q-banding h ave been inconclusive. FISH-technique using whole chromosome painting (WCP) probes should be used to decipher such translocations. We presen t a case where, even after using a battery of probes, the origin of ex tra material on chromosome 15p could not be identified though it was n ot a part of Yq.