The LAN blood group system:a review.

LAN (Langereis) was officially recognized by the International Society of Blood Transfusion in 2012 as being the 33rd human blood group system. It consists of one single high-prevalence antigen,Lan (LANl). The ABCB6 protein is the carrier of the Lan blood group antigen. The ABCB6 gene (chromosome 2q36, 19 exons)encodes the ABCB6 polypeptide (ATP-binding cassette protein,subfamily B, member 6), known as a porphyrin transporter.The exceptional Lan- people do not express ABCB6 (Lan null phenotype), owing to several different molecular mechanisms affecting ABCB6: frameshift leading to a premature stop codon(deletion, insertion, or nonsense mutation of nucleotides);missense mutation; or intronic mutation responsible for RNA splicing defect. Despite the Lan antigen's being reported to play a key role in erythropoiesis and detoxification of cells, Lan people do not appear to demonstrate susceptibility to any disease or seemingly physiologic disorder. Anti-Lan has been described as having variable clinical significance, either for hemolytic transfusion reactions (none to severe) or hemolytic disease of the fetus and newborn (none to mild). Despite challenging conditions caused by the scarcity of Lan- donors worldwide, Lan- blood should ideally be given to patients with anti-Lan, especially those with a high-titer antibody.