Patient survival and microsatellite instability in gliomas by high-resolution fluorescent analysis

Deficient repair of nucleotide mismatches in the genome is considered a maj or factor in tumorigenesis. Such deficiency is evidenced by alterations in dinucleotide repeats of microsatellite sequences, specifically microsatelli te instability (MSI) or replication errors. We investigated the frequency o f MSI in human gliomas in terms of patient outcome. Frequency of MSI was es timated by examining five loci on chromosomes 2, 5, 10, 11, and 13 in 31 gl iomas using high-resolution fluorescent microsatellite analysis. MSI was fo und at all loci in only 2 malignant gliomas (6.5%). MSI was detected at the D10S197 locus in 3 of 11 glioblastomas (27.2%) and 4 of 8 anaplastic astro cytomas (50%), while no MSI was detected in low-grade gliomas. Among patien ts with anaplastic astrocytoma, the 3 with MSI at D10S197 died from local r ecurrence less than 18 months after surgery, while 3 of the patients withou t MSI survived for more than 20 months. MSI at D10S197 may be a prognostic marker for patients with anaplastic astrocytomas.