Case-specific, breakpoint-spanning DNA probes for analysis of single interphase cells.

Balanced reciprocal translocations are known to interfere with homolog pairing in meiosis. Many individuals carrying such chromosomal abnormalities suffer from reduced fertility or spontaneous abortions and seek help in the form of assisted reproductive technology. Although most translocations are relatively easy to detect in metaphase cells, the majority of embryonic cells biopsied in the course of in vitro fertilization (IVF) procedures are in interphase. These nuclei are, thus, unsuitable for analysis by chromosome banding or painting using fluorescence in situ hybridization (FISH). Our assay, based on FISH detection of breakpoint-spanning DNA probes, identifies translocations in interphase nuclei by microscopic inspection of hybridization domains. Probes are selected that span the breakpoint regions on normal homologs. The probes should hybridize to several hundred kilobases of DNA flanking the breakpoint. The two breakpoint-spanning DNA probes for the translocation chromosomes are labeled in separate...