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

Latent immunoglobulin G (Gm) allotypes: occurrence in the cerebrospinal fluid in some neuropathological states

Gm allotypes were detected and quantitated by radioimmunoassay (RIA) in paired serum and CSF samples from patients suffering from various neurological diseases. Of 115 patients with neurological disorders (65 MS and 50 others), seven subjects displayed one or two allotypes in their CSF which were absent in serum. The Gm phenotype in the patient's serum allowed us to infer the genotype without the need of familial data. A comparison of the regression curves obtained in RIA from the unexpected allotype in CSF and the counterpart in a normal serum pool argued for an identity of the Gm antigen carried by both inhibitory molecules. The unexpected allotype(s) in CSF can be considered as the product of a latent Gm gene which may be activated by either immune perturbations due to the disease per se or some particular immune regulations in the central nervous system.

The incidence of Gm allotypes in a group of Iraqi Arabs

Immunoglobulin allotypes were studied in a group of Iraqi Arabs. Results showed that the incidence of the Gm and Km markers investigated fall into the ranges quoted for Caucasian populations, except for the G3m(t) factor which was shown to have an incidence higher than that found in Caucasian groups.

Gene deletion and gene duplication within the cluster of human heavy-chain genes. Selective absence of IgG sub-classes

Individuals with selective absence of IgG1 and IgG2 were discovered by testing for allotypes and isotypes of the respective sub-classes. These individuals were homozygous for sub-class deleted Gm-Am haplotypes, as shown by allotype studies in two families (Gm--;..;g;A2m1/Gm--;n;b;A2m1 and Gm--;n;b;A2m1/Gm--;..;b;A2m1) and by a population study of New Guineans (Gm fa;--;b;A2m2). The individuals with IgG1 sub-class deficiency showed elevation of IgG2, IgG4 and in particular of IgG3. Gene deletion can result from unequal crossing over which renders a complementary chromosome with a duplication of a sub-class gene. In one family, duplication of gamma 3 genes was observed to have happened in one of a twin pair. Quanitation of sub-classes in families with gamma 1- and with gamma 3-duplicated haplotypes did not show increased levels of the gene involved.

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.