ABH antigens one of the systems of blood group antigens having determinants associated with oligosaccharide structures. It is the basis of the ABO system, which was the first human blood group antigen system to be detected, by Austrian-born US pathologist Karl Landsteiner (1868–1943) in 1901, and it remains the most important in blood transfusion. Individuals
abetalipoproteinemia or (Brit.) abetalipoproteinaemia an autosomal recessive disorder in which plasma lipoproteins lack apolipoprotein B. There is defective assembly and secretion both of chylomicrons in intestinal mucosa and of very-low-density lipoproteins in the liver. The cause is a deficiency of the 88 kDa subunit of microsomal triglyceride transfer protein.
ABC transporter a membrane transport protein having the ABC molecular domain, named after ATP-binding cassette, characteristic of all members of a large superfamily of membrane transport proteins that hydrolyse ATP and transfer a diverse array of small molecules across membranes.