Human immunoglobulin heavy-chain multigene deletions in healthy individuals.

Extensive multigene deletions have been described in the human immunoglobulin heavy-chain constant region genes, some of them encompassing perhaps more than 100 kilobases. These deletions have all been observed in healthy individuals although these individuals lacked several immunoglobulin class or subclasses, being either homozygous for one deletion or heterozygous for two different deletions. The high frequency of consanguinity in the Tunisian population accounts for the high frequency of individuals displaying one or the other of these deletions in a homozygous state.