CHARACTERIZATION OF 12 MICROSATELLITE LOCI OF THE HUMAN MHC IN A PANEL OF REFERENCE CELL-LINES

The human genome contains a large number of interspersed microsatellit e repeats which exhibit a high degree of polymorphism and are inherite d in a Mendelian fashion, making them extremely useful genetic markers . Several microsatellites have been described in the HLA region, but a llele nomenclature, a set of broadly distributed controls, and typing methods have not been standardized, which has resulted in discrepant m icrosatellite data between laboratories. In this report we present a d etailed protocol for genotyping microsatellites using a semi-automated fluorescence-based method. Twelve microsatellites within or near the major histocompatibility complex (MHC) were typed in the 10th Internat ional Histocompatibility Workshop homozygous typing cell lines (HTCs) and alleles were designated based on size. All loci were sequenced in two HTCs providing some information on the level of complexity of the repeat sequence. A comparison of allele size obtained by genotyping ve rsus that obtained by direct sequencing showed minor discrepancies in some cases, but these were not unexpected given the technical differen ces in the methodologies. Fluorescence-based typing of microsatellites in the MHC described herein is highly efficient, accurate, and reprod ucible, and will allow comparison of results between laboratories.