However, multiple gene deletions in this region produce at least three categories of gene arrangements: (a) C4A-CYP21P/CYP21-TNXB, in which there is a CYP21P/CYP21 fusion gene.     ///    Most of these gene arrangements probably exist in the C4A-XCYP21-TNXB and C4A-CYP21P/CYP21-TNXB gene loci.     ///    Formation of the C4A-CYP21P/CYP21-TNXB locus produced four distinct CYP21P/CYP21 chimeras. 