A Genetic Marker of Human IgE Heavy Chains, Em(1)¹

Abstract

A monoclonal anti-IgE antibody was obtained that reacted with some IgE myeloma proteins and with all but a few normal sera. Family studies proved that a genetic marker of IgE had been detected. This allotype, called Em(1), segregates in association with certain Gm-Am haplotypes. The available quantitative evidence warrants the conclusion that human IgE has genetic variants, but no subclasses. Samples from various populations of five continents, representative for the respective prevalent Gm-Am haplotypes, were tested for Em(1). Em(1) was absent mainly in haplotypes carrying A2m(2) and G2m(n). These closely linked genes are located in a chromosomal region that comprises the gamma 2-gamma 4-epsilon-alpha 2 CH genes. A hypothesis for the generation of Em(1) is given.

GM haplotype diversity of 82 populations over the world suggests a centrifugal model of human migrations

“…GM allotypes carried by IgG immunoglobulins are informative serological markers whose transmission as haplotypes may provide more information than single polymorphisms considered as independent markers (reviewed by Lefranc and Lefranc, 1990). Four systems of allotypic antigens have been described so far: GM, AM, EM, and KM (Grubb, 1956; Kunkel et al, 1969; Ropartz et al, 1961; van Loghem et al, 1984; Vyas and Fudenberg, 1969). The GM system with 18 allotypes shows the greatest degree of polymorphism, and is therefore most often studied in population genetics.…”

Mechanism of resistance to cetuximab therapy in colorectal cancer

“…It would be of interest to determine whether a genetic marker identified on IgE, EM(1), 14 influences the anti-IgE response to this oligosaccharide, just as the IgG2 allotype GM 23 influences the anti-IgG2 responses to polysaccharide antigens 4 , 5 . If a significant relationship between EM(1) and anti-IgE responses to the oligosaccharide is established, it could help identify suitable subjects for cetuximab therapy.…”

Immunoglobulin Allotypes in Hungarian Gypsies

“…G3m(u) was determined in G3m(s) positive samples. The classical method of agglutination-inhibition was used for Gm, Am and Km typing; Em typing was by radioimmunoassay (for reagents and methods, see van Loghem et al, 1984).…”