ISCN rules in FISH analysis: how to report a rare recombinant chromosome?

Unbalanced chromosomes are often the result of inheritance of a balanced chromosome rearrangement from one parent. During meiotic segregation, the chromosomes with balanced alterations in the parent may "unbalance" in the gametes and, consequently, in the offspring, resulting in a partial gain and a partial loss of different regions of that chromosome. We present the FISH results of two samples (mother and daughter) to confirm the underlying rearrangement of the chromosome 4 alterations detected in the daughter's chromosomal microarray analysis (dup4p16.3 and del4q35) and to confirm the presence of a pericentric inversion of chromosome 4 in the mother.

In the analysed metaphases of the mother’ssample, the observation of the subtelomeric regions allowed to identify a chromosome 4 with a pericentric inversion.
In the analysed metaphases of the daughter’ssample, it was observed a normal subtelomeric pattern for one of the chromosomes 4, while in the other chromosome, in place of the normal subtelomeric region of the long arm (4qter), one signal was observed for the subtelomeric region of the short arm of the same chromosome.