Table 1.

Summary of the various antibody numbering schemes used for framework and complementary determining region identification

Numbering Scheme	Pros	Cons
Kabat [85–91]	Based on sequence alignment. Includes v-region of antibodies and T cell receptor. Basis of KABATMAN database. Considered standard	Based on limited numbers of sequences. May be biased as it is based on most common length sequence. Unconventional insertion or deletion in FWRs not included. Do not match well with 3D structure
Chothia [92–94]	Based on crystal structure alignment. Better CDR definition reflected in structural loop. Can be optimized by defining new insertion points	Possible confusion when used with other schemes. Based on most common CDR length. Ignores sequence with unconventional length. Insertion points are not consistent
Martin [95]	Uses larger Abysis database. Based on structural alignment. Accept unconventional length sequences. Uses ABnum software based on Chothia. Considered to be the upgraded version of Chothia scheme. Incorporate database from IMGT, Kabat and Chothia	May incorporate all the weakness from various database
Gelfand [96–100]	Features “two span bridge.” Precise comparison of secondary structures in aligned sequences	Complex nomenclature. Does not include gaps and deletions. Definition of CDR loops is different from other schemes
IMGT [101–108]	Based on Ig superfamily from different species. Based on germ-line V gene alignment. Includes variable region of antibodies and T cell receptor. Uses continuous numbering system. Used by WHO-IUIS	Due to continuous numbering system, it is difficult to visualize insertions. Less flexible. Difficulty adapting to sequences with new insertions
Honneger (AHo’s) [109]	Based on structural alignment. Pre-defined C23, W43, C106 and G140 as conversed residues. Takes into account of “two span bridge” conformation in CDR1. Matches well to antibody structures	Conserved residues positions are only from 28 structures. Possibility of number skipping. Less flexible on insertions