DNA fiber FISH detection of HLA-DQ and -DR deletions.

Schematic representation of part of the HLA class II and class III region of a DR 4, 7, or 9 haplotype, showing the approximate localization of clones used for fiber FISH. Black bars represent expressed genes, and white bars represent pseudogenes in the class II region. Microsatellite markers X87 344, D6S1666, and C47 are boxed. DNA-fiber FISH of 8 extranodal lymphoma cases with various deletions in the HLA class II region is depicted. In all cases except case T16, 1 allele contained a deletion involving all used probes. In these cases, the allele with a small deletion is shown. In case T16, both alleles DR5 and DR7 contained a deletion as illustrated.