STRUCTURE OF THE HUMAN TYPE-IV COLLAGEN COL4A5 GENE

The complete exon size and distribution pattern of the human alpha 5(I V) collagen gene COL4A5 has been determined. Seventeen genomic lambda phage clones, eight of which have been described previously (Zhou, J., Hostikka, S. L., Chow, L. T., and Tryggvason, K. (1991) Genomics 9, 1 -9), spanning about 160 kilobases of DNA contained 140 kilobases of th e gene itself. The clones covered the entire gene with the exception o f exons 2 and 37 and their flanking regions so that the exact gene siz e could not be determined. The sequences of these two exons were, howe ver, determined from polymerase chain reaction products. The COL4A5 ge ne has a structure highly homologous with that of COL4A5 which encodes the alpha 1(IV) chain, However, the COL4A5 gene contains 51 exons, or one less than COL4A1. The exon size pattern of the genes are similar, with 41 exons having identical sizes. Ah the exons were assigned to d istinct EcoRI restriction fragments. The results may be useful for cha racterization of mutations in COL4A5 in patients with X chromosome-lin ked Alport syndrome.