Detection of VH-CH transcripts of the IgH gene.
VH-CH transcripts were amplified by RT-PCR with lymphoma-specific 5′ primers and isotype-specific 3′ primers, transferred to nylon membranes, and labeled by isotype-specific probes (A). The identity of the PCR products was confirmed by cloning and sequencing. In case 3, an abnormally large Igα transcript was observed. Sequence analysis of this transcript (B) revealed an aberrant VH-Cα splicing, caused by a T>G transversion within the regular donor splice site at the 3′ end of VHDHJH6 (single arrow) and use of a cryptic donor splice sequence (double arrows mark the first 2 bases of cryptic donor site). As a result, VHDHJH6 and Cα exon 1 (both indicated by gray background) are separated by a 373-bp intronic sequence. Note the high rate of somatic hypermutation carried far into the intron. This sequence has been submitted to the EMBL/GenBank/DDBJ database under accession number AJ292071.
