INCIDENCE OF LOW-FLUORESCENCE A SATELLITE REGION ON CHROMOSOME-21 ESCAPING DETECTION OF ANEUPLOIDY AT INTERPHASE BY FISH

Aneuploidy detection for chromosome 21 by fluorescence in situ hybridi zation (FISH) to interphase nuclei using a probe specific for the alph oid DNA sequences D21Z1/D13Z1 should be avoided. An extreme heteromorp hism, resulting in misdiagnosis if interphase FISH is the only test em ployed, may be far more frequent (4/101) than expected.