Loci, genes or chains is a query from the 'Taxonomy, ...' module in
IMGT/LIGM-DB.
It allows to retrieve sequences identified by reference to a locus, to a gene or to a chain.
Examples:
Ig-Heavy refers to the IGH locus, to the IGH genes or to the Ig heavy chains.
TcR-Beta-2 refers to the TRBC2 genes or to the TcR beta2 chains.