Evidence for somatic pairing of chromosome 7 and 10 homologs in a follicular lymphoma

Fluorescence in situ hybridization using centromeric probes for chromosomes 7 and 10 in a follicular lymphoma revealed only one signal in about 40% of interphases, whereas two copies of each chromosome were consistently seen in metaphases. In four out of 18 metaphases both copies of chromosome 7 were situated close to one another. In contrast, two signals for chromosome 1 were seen in 94% of interphases, consistent with observations on metaphases. The findings suggest chromosome-specific somatic pairing, the functional significance of which is at present unknown, and reinforce previous evidence suggesting that care should be taken in the interpretation of interphase signal numbers using centromeric probes in neoplastic as well as normal material.