Loss of heterozygosity is the observation that malignant tissues
present in an individual bearing a tumor supressor gene
mutation or deletion tend to have a mutated or deleted allelomorph at
the locus of the tumor suppresor gene in question in the transformed tissue.
Global microsatellite instability, particularly in hereditary, non-polyposis
colon cancer, is thought to be a consequence of a deficit in
mismatch repair capacity, specifically, in hMSH2 (the mammalian
homolog of bacterial mutS) and other proteins required for the
assembly of the mismatch repair complex. See the work of
Paul Modrich of Duke U., 1994-'95 and Kolodner and Fishel, '93-'95.
The two are disparate manifestations of malignancy on the molecular
level, and do not appear to me to be conceptually conjoined.
Diverse views welcomed!
Bert Gold, Ph.D.
University of California, San Francisco
Program in Medical Genetics