A New Variant of Human Transferrin in a Venezuelan Family

Abstract

THE most prolific of the hereditary variations among the human serum proteins is that of the iron-transport protein transferrin. The initial demonstration of genetically determined transferrin heterogeneity¹ has been followed by numerous reports of additional variants, until at the present time thirteen transferrins have been described: B₀ (ref. 2), B_0–1 (ref. 3), B₁ (ref. 4), B₂ (ref. 5), B₃ (ref. 6), C, D₀ (ref. 2), D₄ (ref. 7), D_Montreal (ref. 8), D_Chi (ref. 6), D₁ (ref 9), D₂ (ref. 4), and D₃ (ref. 2). Each of the molecular species of transferrin has been identified by its characteristic mobility in starch-gel electrophoresis. Transferrin C is common in all populations; variants of more rapid mobility than transferrin C have been named B, and slower-moving variants have been labelled D. Where convenient, subscripts have been chosen to define the relative electrophoretic mobilities of variants within the fast- and slow-moving categories. In certain cases, particular transferrins appear to be restricted to specific populations; thus, transferrin B_0–1 occurs in 8 per cent of Navajo Indians, B₂ in 1 per cent of Caucasians, D_Chi in 6 per cent of Chinese, and D₁ in 10 per cent of American Negroes.