Frequent loss of heterozygosity on chromosome 6p in uveal melanoma

Lack of expression of HLA class I antigens is frequently observed on primar y uveal melanoma, and is correlated with improved pat-lent survival. Severa l mechanisms may contribute to the observed loss of HLA class I expression, including changes at the DNA level. In this study, we used microsatellite analysis as a molecular genetic approach to examine loci on chromosome 6p f or loss of heterozygosity (LOH). Three pairs of microsatellite markers were used co screen 20 formalin-fixed, paraffin-embedded uveal melanomas for LO H on the short arm of chromosome 6. In all cases, normal adjacent scleral t issue was used as a control. We identified LOW in eleven cases from microsa tellite locus D6S105 to the telomere, in eight cases from microsatellite lo cus D6STNFa to the telomere (area includes D6S105), and in seven cases from microsatellite locus D6S291 to the end of chromosome 6p (includes D6STNFa and D6S105). In seven cases, retention of heterozygosity was found at all t hree loci using these primers. Our results suggest that loss of heterozygos ity on chromosome 6p is a common feature in uveal melanoma. We did not find a correlation between the presence of LOH and locus-specific HLA-A and -B expression. (C) American Society for Histocompatibility and Immunogenetics, 1999. Published by Elsevier Science Inc.