title: Recombination, mutation, or constitutive expression at a Gm locus and familial hypergammaglobulinemia.
abstract: 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.
mesh_terms: D000293:Adolescent; D000328:Adult; D002648:Child; D002675:Child, Preschool; D005260:Female; D005796:Genes; D008040:Genetic Linkage; D005838:Genotype; D006801:Humans; D006937:Hypercholesterolemia / Q000235:genetics; D006942:Hypergammaglobulinemia / Q000235:genetics*; D007126:Immunoglobulin Allotypes; D008297:Male; D009154:Mutation; D010375:Pedigree; D011995:Recombination, Genetic
chemical_list: D007126:Immunoglobulin Allotypes