Characterization of a complex rearrangement involving chromosomes 1, 4 and 8 by FISH and array-CGH

Complex chromosomal rearrangements (CCRs) are structural aberrations involving more than two chromosomes with at least three breakpoints. CCRs can be divided into familial and de novo. Balanced CCR are extremely rare in humans and are at high risk of producing unbalanced gametes. Individuals with balanced CCR are usually phenotipically normal but report fertility problems, recurrent miscarriages or congenital anomalies in newborn offsprings as consequence of either meiotic failure or imbalanced chromosomes segregation.We describe the case of an unbalanced CCR involving chromosomes 1, 4 and 8 found in a girl with developmental delay, hexadactilia and microcephaly. The rearrangement, apparently balanced at a standard karyotype analysis and of maternal origin, was demonstrated to be unbalanced by array-CGH and FISH. In conclusion our study underlines the importance of the combined use of a quantitative technique, as array-CGH, to detect criptic segmental aneuploidies, and a qualitative tool, as FISH analysis, to physically map the localization of the chromosome segments involved, in order to realize the exact nature that underlies a chromosomal rearrangement.