The Journal of Immunology, Vol 152, Issue 1 129-135, Copyright © 1994 by American Association of Immunologists

ARTICLES

Structural and immunologic analysis of gene triplications in the Ig heavy chain constant region locus

A Brusco, U Cariota, A Bottaro, C Boccazzi, A Plebani, AG Ugazio, R Galanello, AM van Leeuwen, GG DeLange and S Depelchin
Dipartimento di Genetica, Biologia e Chimica Medica, Universita di Torino, Italy.

The Ig H chain C region is a multigene family often involved in genomic rearrangements leading to deleted and duplicated haplotypes, most probably through unequal crossing over between homologous regions within the locus. The frequency of these haplotypes in Italy is around 2.7% each. Using PFGE analysis in two unrelated Italian families we found an abnormal high m.w. band, inherited in a Mendelian fashion. To assess the extension of the haplotype we performed Southern blot analysis using several specific Ig H chain C probes. In both cases, the haplotype turned out to be triplicated, with three copies of the genes from A1 to E. In one family segregation of a duplication from EP to G4 was also observed. Analysis of polymorphic loci suggests that the two triplications are of independent origin. Serological detection of IgA2 allotypes demonstrated the functional activity of the genes at the 3' end of the triplicated locus, ruling out any major effect of these large genomic rearrangements on Ig class switching. Furthermore, the triplicated haplotype does not seem to give rise to any clinically significant immunological impairment or increase in Ig serum concentrations.

This article has been cited by other articles:

				A. Brusco, S. Saviozzi, F. Cinque, A. Bottaro, and M. DeMarchi A Recurrent Breakpoint in the Most Common Deletion of the Ig Heavy Chain Locus (del A1-GP-G2-G4-E ) J. Immunol., October 15, 1999; 163(8): 4392 - 4398. [Abstract] [Full Text] [PDF]