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.
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.
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.
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).
Compound heterozygosity for a disease-causing G1489E [corrected] and disease-modifying G530S substitution in COL5A1 of a patient with the classical type of Ehlers-Danlos syndrome: an explanation of intrafamilial variability?
Thus, although as many as one-half of the mutations that give rise to EDS types I and II are likely to lie in the COL5A1 gene, a significant portion of them result in very low levels of mRNA from the mutant allele, as a consequence of nonsense-mediated mRNA decay.
COL5A1 exon 14 splice acceptor mutation causes a functional null allele, haploinsufficiency of alpha 1(V) and abnormal heterotypic interstitial fibrils in Ehlers-Danlos syndrome II.
Dermal fibroblasts derived from types I and IV Ehlers-Danlos syndrome (EDS) patients, carrying mutations in COL5A1 and COL3A1 genes, respectively, synthesize aberrant types V and III collagen (COLL) and show defective organization of these proteins into the extracellular matrix (ECM) and high reduction of their functional receptor, the alpha(2)beta(1) integrin, compared with control fibroblasts.
Dermal fibroblasts derived from types I and IV Ehlers-Danlos syndrome (EDS) patients, carrying mutations in COL5A1 and COL3A1 genes, respectively, synthesize aberrant types V and III collagen (COLL) and show defective organization of these proteins into the extracellular matrix (ECM) and high reduction of their functional receptor, the alpha(2)beta(1) integrin, compared with control fibroblasts.
EDS cells with COL5A1 haplo-insufficiency deposited less than one-half of hydroxyproline as collagen compared to control fibroblasts, though total collagen synthesis rates are near-normal because type V collagen represents a small fraction of collagen synthesized.
Mutations in the genes encoding for type V collagen have been found in the classical type of Ehlers-Danlos syndrome (EDS); the most common mutations lead to a non-functional COL5A1 allele.
Mutations in COL5A1 and COL5A2, encoding the type V collagen proalpha1- and proalpha2-chain, are found in approximately 50% of patients with classic EDS.
In dermal fibroblasts from our population of 76 individuals with clinical features of classical EDS, there were 21 (29.5%) with decreased expression of one COL5A1 allele, consistent with published estimates of the frequency of null alleles.
We identified a novel COL5A1 N-propeptide acceptor-splice site mutation (IVS6-2A>G, NM_000093.3_c.925-2A>G) in a patient with cutaneous features of EDS, severe progressive scoliosis and eye involvement.