a, Protein sequence alignment of MGC1 and MGD21 with germline-encoded sequences of the corresponding VH (green or purple), DH (cyan), JH (blue) and LAIR-1 (exon in red and intronic sequences in light red). Chr13 sequences are shown in orange while grey areas show junctional sequences for which no homology was found. b-c, Genealogy trees drawn from the VH nucleotide sequences of antibodies from donors C (b) and D (c). In the donor C genealogy tree, antibodies that use different light chains are highlighted in different colors. Shown are the nucleotide and amino acid substitutions, with the latter in parentheses. d, Scheme showing genomic DNA and cDNA of LAIR-1-containing antibodies from donors C and D. Shown are the lengths of the fragments (bp in parentheses), cryptic 12 and 23 RSS sites (black and brown triangles, respectively) and splicing positions (dashed lines).