Analysis of V_H–constant region transcripts from case 83.

Alignment is made to the closest germline gene segments V_3-23 and J_H 4b (bold characters). By means of leader (for IgM and IgD) or V_H primers (for IgA and IgG), together with constant region primers for μ, δ, γ, and α, transcripts for IgM, IgD, IgG2, IgG1, IgA1, and IgG3 were identified. All isotype transcripts share an identical mutational grade of homology to the germline sequence. Identical intraclonal variations, like GG → AA substitution (amino acid G → N) in codon 55 or C → G in codon 101, are seen in different isotype transcripts. Letters and numbers above germline sequence indicate amino acid sequence and codon numbers. The number of identical clones are indicated. Sequence identity is shown by dots; mutations are shown by mismatch characters.