The variation in expression in this family suggests that EDS types I and II are allelic, and the linkage data support the hypothesis that mutation in COL5A1 can cause both phenotypes.
This demonstrates that a mutation in a type V collagen gene, COL5A1, results in EDS type I, and shows the involvement of L1 sequences in a constitutional chromosomal translocation.
However, linkage studies in other EDS I families indicate the disorder is heterogeneous; linkage to both COL5A1 and COL5A2 was excluded in two other families with EDS I while a fourth family was concordant for linkage to COL5A1 (Z = 2.11; theta = 0.00).
Using an intragenic simple sequence repeat polymorphism, we report linkage of the COL5A1 gene, which encodes the alpha 1(V) chain of type V collagen, to EDS II.