The influence of gene deletions and duplications within the IGHC locus on serum immunoglobulin subclass levels.

To study the influence of heterozygous gene deletions and duplications in the human IGHC region on serum concentrations of antibodies, we have analyzed the IgG subclass levels in a large number of individuals from three different populations. Our results show that heterozygous gene deletions of the C gamma 1, C gamma 2, or C gamma 4 genes are all associated with a lower mean serum level of the affected subclass whereas duplication of the C gamma 2 or C gamma 4 genes result in either no change (IgG2) or a slightly elevated (IgG4) level of serum immunoglobulins.