A gamma 3 hinge region probe: first specific human immunoglobulin subclass probe.

We report the first specific human immunoglobulin subclass probe which was obtained by subcloning the gamma 3 hinge region. This specific gamma 3 probe allowed us to identify with certainty the C gamma 3 gene on Southern genomic blots, to describe the first C gamma 3 restriction fragment length polymorphism (EZZ gamma 3 RF) and to show that an IgG3 selective deficiency, previously described serologically, was not due to a deletion of the C gamma 3 gene. Such a probe should be particularly useful for screening libraries from individuals with IgG3 immunodeficiencies or presenting unusual C gamma 3 genes and, consequently, for studying the C gamma gene evolution.