Human collagen genes encoding basement membrane alpha 1 (IV) and alpha 2 (IV) chains map to the distal long arm of chromosome 13.

At least 20 genes encode the structurally related collagen chains that comprise greater than 10 homo- or heterotrimeric types. Six members of this multigene family have been assigned to five chromosomes in the human genome. The two type I genes, alpha 1 and alpha 2, are located on chromosomes 17 and 7, respectively, and the alpha 1 (II) gene is located on chromosome 12. Our recent mapping of the alpha 1 (III) and alpha 2 (V) genes to the q24.3----q31 region of chromosome 2 provided the only evidence that the collagen genes are not entirely dispersed. To further determine their organization, we and others localized the alpha 1 (IV) gene to chromosome 13 and in our experiments sublocalized the gene to band q34 by in situ hybridization. Here we show the presence of the alpha 2 type IV locus also on the distal long arm of chromosome 13 by hybridizing a human alpha 2 (IV) cDNA clone to rodent-human hybrids and to metaphase chromosomes. To our knowledge, these studies represent the only demonstration of linkage between genes encoding both polypeptide chains of the same collagen type.