title: Evidence for "deleted" or "silent" genes homozygous at the locus coding for the constant region of the gamma3 chain.
abstract: Three uncommon stable Gm haplotypes, Gm3;23;--, Gm1,2,17;..;-- and Gm1,17;..;-- have been transmitted through 3 generations of two related Lebanese and Syrian families. No pathological consequence was noted in seven individuals, aged 14--65, whose sera were deficient for all the allotypes carried by the IgG3 chains. Among the different genetic events which could have produced these haplotypes (alteration of a regulatory gene, point mutation, gene hybridization, gene deletion), it appears that a structural deletion is the most probable explanation. The observed data can be explained by either a partial or a total deletion of the constant portion of the IgG3 heavy chain.
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000941:Antigens; D002874:Chromosome Mapping; D005260:Female; D005796:Genes; D005838:Genotype; D006801:Humans; D007126:Immunoglobulin Allotypes; D007074:Immunoglobulin G; D007861:Lebanon / Q000208:ethnology; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D010375:Pedigree; D010641:Phenotype; D013593:Syria / Q000208:ethnology
chemical_list: D000941:Antigens; D007126:Immunoglobulin Allotypes; D007074:Immunoglobulin G