Quantitative studies of Gm allotypes. V. Simultaneous presence of latent Gm allotypes and deficient Gm genes in a family with hypogammaglobulinaemic probands

A study of Gm allotypes in a Caucasoid family with hypogammaglobulinaemic probands, showed qualitative (unexpected or lacking Gm allotypes) and quantitative (increased or decreased Gm contents) abnormalities in many relatives. Part of these observations can be most probably accounted for by inheritance of a GM1,17; 5,28 haplotype, not described in Caucasians yet, and by an in vivo expression of latent Gm genes.

Quantitative studies of Gm allotypes. II. G1m(1), G3m(5) and G3m(21) in sera from healthy caucasoid blood donors, and in a family with the inheritance of a gene responsible for a weak Gm1,17;..;21 haplotype

The quantitative expression of three allotypes--G1m(1), G3m(5) and G3m(21)--has been studied in normal caucasoid sera. A gene dosage effect, previously described for all of these allotypes, is not noticed for G3m(5) in the present study. The different content of G3m(5) and G3m(21) IgG3 molecules in heterozygous Gm5/Gm21 sera has been verified: these contents are respectively 75% and 25% of the IgG3 content. The same allotypes have been studied in a family which shows the inheritance of a weak Gm1,17;21 haplotype. The gene responsible for this abnormality is probably a new regulatory gene, and is transmitted without the 'aimed' haplotype.

Recombination, mutation, or constitutive expression at a Gm locus and familial hypergammaglobulinemia

In a hypercholesterolemic Lebanese family, an uncommon Gm haplotype carrying an unexpected C gamma 1 gene was inherited by only one of 10 siblings. A new recombination during the maternal or paternal meiosis could explain its formation. According to this hypothesis, our data would be informative for the linkage relationship between the gamma-cistrons and the alpha 2-cistron. The latter might be located near the N-terminal side of the gamma-cistron linkage group, and the sequence of genes would be alpha 2, gamma 4, gamma 3, and gamma 1. A mutation could also effect the change from G1m(17) (codons AAA and AAG) TO G1m(3) (codons AGA and AGG). Another alternative is to postulate a constitutive expression of a C gamma 1 structural gene which, normally, would not be expressed. The uncommon derepression could be the consequence of uncommon cellular response to environmental, pathological or metabolic perturbation of a regulatory mechanism.

Quantitative studies of Gm allotypes. I. Reappraisal of the method using an autoanalyzer

In this study, various parameters for the autoanalyzer hemagglutination-inhibition circuit applied to Gm studies, were examined. Details are given of modifications of this circiut and related methodology, that improve its precision and the reproducibility of results: use of a cells counter, effects of temperature, PVP, Tween 20, anti-Gm concentration, etc. The effects of age, storage and freezing on quantitative Gm allotypes antigenicity are also stressed.