Use of fluorescence in situ hybridization to clarify a complex chromosomal rearrangement in a child with multiple congenital anomalies.

A child with multiple congenital anomalies was referred for cytogenetic evaluation. G-banded analysis showed a complex chromosome rearrangement involving 6 different chromosomes and 10 breakpoints. Fluorescence in situ hybridization (FISH) using whole chromosome painting probes and repetitive sequence probes was performed. In most cases the painting probes alone helped to clarify the G-banded results. However, in one instance, where the terminal band of the long arm of chromosome 1 was involved, the use of a telomeric probe was essential in defining the rearrangement.