PRENATAL IDENTIFICATION OF DE-NOVO MARKER CHROMOSOMES USING MICRO-FISH APPROACH

Chromosome microdissection combined with polymerase chain reaction (PC R) and reverse chromosome painting ('micro-FISH') is a powerful techni que for the unequivocal identification of complex or subtle chromosoma l aberrations. We have applied this technique to the prenatal diagnosi s of three fetuses with lie novo marker chromosomes. One small supernu merary satellited marker chromosome was shown to have originated from the fusion of the centromeric heterochromatin of one or both of chromo somes 14 and 22. The second marker was identified as i(9)(p10) while t he third marker chromosome was shown to have been derived from the 1p1 3.1-1q21.3 region. At birth, the clinical outcome correlated well with that expected from the prenatal cytogenetic findings. Our study highl ights the importance of the application of 'micro-FISH' to prenatal di agnosis.