Instability at the H-ras minisatellite is associated with the spontaneous abortion of the embryo.

Recently we have shown that microsatellite instability (MI) is a detectable phenomenon in aborted embryonic tissues. In the present study we investigated if instability is also detectable in a minisatellite located at the 3'-end of the H-ras proto-oncogene, affecting either the repetition number of the 28-bp core generating larger or smaller alleles or its sequence creating a detectable restriction fragment length polymorphism (RFLP). Among 30 aborted embryonic tissues, alterations at the repetition number of the core were found in 3 (10%) while point mutations were detected in 7 (23%) cases. These results indicate that structural alterations of the H-ras minisatellite may be associated with the rejection of the embryo.