Highly polymorphic apolipoprotein A-IV locus in the baboon.

Apolipoprotein A-IV is found in mesenteric lymph chylomicrons, very low density lipoprotein particles, high density lipoprotein particles, and in the lipoprotein-free fraction of plasma. Apolipoprotein A-IV is polymorphic in a variety of species including human, dog, and horse. Efforts to estimate the impact of apolipoprotein A-IV structural variation on quantitative lipid levels in humans have been limited by the low frequency of the less common alleles. In the baboon, Papio hamadryas anubis, we have found apolipoprotein A-IV to be highly variable at the protein level with five alleles appearing at polymorphic frequency. We have confirmed the autosomal codominant inheritance of these five alleles in pedigreed baboons. The baboon has been shown to be a suitable animal model for the study of atherosclerosis, and the existence of a common, multi-allele apolipoprotein A-IV polymorphism in the baboon may be useful in elucidating the role of apolipoprotein A-IV in lipid metabolism.