Fiber FISH with bar codes of probes for the

BCL2 gene and IGH locus.The top fiber shows a hybridization pattern representing a germlineBCL2 allele. The second fiber is a rearrangement pattern, as observed in case FL4104. It represents the derivative chromosome 18 from which the BCL2 gene was deleted. The third fiber is the hybridization pattern of a germline IGH allele. The position of Cγ genes and JH, DH, and VH regions is indicated.2 The last fiber shows an insertion of theBCL2 gene into the IGH locus. The CHgene region is juxtaposed to the 5′-side of the BCL2 gene. At the 3′-side, part of cosmid U2-2, containing most of the DH region, is present (labeled in red). Because in this image the most 3′-BCL2 cosmid is also in red, the breakpoint junction is not visible. Hybridization of these probes in different colors confirmed the juxtaposition of cosmid U2-2 to the BCL2 gene (not shown).