THE IGHG3 GENE SHOWS A STRUCTURAL POLYMORPHISM CHARACTERIZED BY DIFFERENT HINGE LENGTHS - SEQUENCE OF A NEW 2-EXON HINGE GENE

Four of the five human IGHG genes (G1, GP, G2, and G4) display a hinge region consisting of a unique exon. In contrast, IGHG3 exhibits a dif ferent structure in which the hinge is constituted by four or, less fr equently, three exons. We report here the nucleotide sequence of a new 2-exon hinge G3 gene found in a Mandenka individual from Eastern Sene gal. A comparison of this sequence with that of 4-exon and 3-exon hing e G3 genes suggests that the 3-exon and 2-exon hinge forms arose indep endently by deletion events in a 4-exon hinge gene.