title: Familial clustering of IGHC deletions and duplications: functional and molecular analysis.
abstract: The human immunoglobulin heavy chain constant region locus (IGHC) comprises nine genes and two pseudogenes clustered in a 350 kilobase (kb) region on chromosome 14q32. Several IGHC haplotypes with single or multiple gene deletions and duplications have been characterized. The most likely mechanism accounting for these unusual haplotypes is the unequal crossing-over between homologous regions within the locus. Here we report the analysis of an unusual case of familial clustering of deletions/duplications. In the two branches of the BON family, three duplicated and two deleted haplotypes, all probably independent in origin, have been characterized. The structure of the haplotypes, one of which is described here for the first time, supports the hypothesis of homologous unequal crossing-over as the origin of recombinant haplotypes. The analysis of serological markers in a subject carrying one deleted and one duplicated haplotype allowed us the first direct inferences concerning the functions of the duplicated IGHC haplotypes.
authors.affiliation: Dipartimento di Genetica, Biologia e Chimica medica, Torino, Italy.
authors.forename: A
authors.initials: A
authors.lastname: Bottaro
authors.forename: R
authors.initials: R
authors.lastname: Gallina
authors.forename: A
authors.initials: A
authors.lastname: Brusco
authors.forename: U
authors.initials: U
authors.lastname: Cariota
authors.forename: C
authors.initials: C
authors.lastname: Boccazzi
authors.forename: M R
authors.initials: MR
authors.lastname: Barilaro
authors.forename: A
authors.initials: A
authors.lastname: Plebani
authors.forename: A G
authors.initials: AG
authors.lastname: Ugazio
authors.forename: A M
authors.initials: AM
authors.lastname: van Leeuwen
authors.forename: G G
authors.initials: GG
authors.lastname: DeLange
mesh_terms: D000293:Adolescent; D000328:Adult; D015139:Blotting, Southern; D002648:Child; D004406:Dysgammaglobulinemia / Q000235:genetics; D005260:Female; D017353:Gene Deletion; D006239:Haplotypes; D006801:Humans; D007143:Immunoglobulin Heavy Chains / Q000235:genetics*; D007132:Immunoglobulin Isotypes / Q000097:blood / Q000235:genetics; D008297:Male; D008875:Middle Aged; D005810:Multigene Family / Q000235:genetics*; D010375:Pedigree
chemical_list: D007143:Immunoglobulin Heavy Chains; D007132:Immunoglobulin Isotypes