Said {TAIL ~ additional constant region segment} comprises a switch region and human constant region coding segment, wherein {HEAD ~ the constant region coding segment} is operably linked to a switch region that it is not normally associated with, i.e., a non cognate switch region 
Said { TAIL ~ additional constant region segment } comprises a switch region and human constant region coding segment , wherein { HEAD ~ the constant region coding segment } is operably linked to a switch region that it is not normally associated with , i.e. , a non cognate switch region
OTH TAIL TAIL TAIL TAIL TAIL TAIL TAIL TAIL OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD HEAD OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH OTH