Early pre-B cells from normal and X-linked agammaglobulinaemia produce C mu without an attached VH region.
Schwaber J, Molgaard H, Orkin SH, Gould HJ, Rosen FS. Early pre-B cells from normal and X-linked agammaglobulinaemia produce C mu without an attached VH region. Nature. 1983 Jul 28-Aug 3; 304(5924):355-8.