Ehler-Danlos syndrome type IV; vascular type (EDS type IV, vEDS), is a dominant disease caused by mutations in COL3A1, which encodes collagen III. Collagen III is a major component of collagen fibrils in the extracellular matrix (ECM) of hollow organs such as the lungs, uterus and vascular tissues, as well as skin. Collagen III consists of three identical COL3A1 α chains coiled around each other, a homotriplex that is secreted from cells for fibril assembly. For this reason, COL3A1 α chain defects (missense or premature termination of translation) affect collagen III homotrimer formation and fibril assembly. Mutations in collagen III are reported to affect production, secretion and thermal stability. These biochemical abnormalities influence collagen III ECM assembly leading to vEDS symptoms, which include skin hyper-flexibility, easy bruising, joint hypermobility and delayed wound healing. However, the major symptom that causes death is vascular rupture in the internal organs. The first step in designing any genetic therapy to address vEDS mutations is their precise identification. In this study, we used RNA-based screening to identify mutations in this 51-exon gene. A c.766delA nonsense mutation resulting in a pronounced reduction of mRNA levels due to nonsense mediated decay. Furthermore, splice site mutations, IVS7+5G>A and IVS14-2A>G were detected in patient cells after skipping of exon 7 and exon 15 was identified by RNA-based screening.
Recently, antisense oligonucleotides (AOs) have been approved to by-pass dystrophin protein-truncating mutations in a clinical setting for Duchene muscular dystrophy. Moreover, COL3A1 has several similarities with dystrophin: (i) consists of many exons, some of which can be skipped without affecting function (ii) both encode a long half-life structural protein. According to these similarities, AO mediated splicing could also be a potential therapy for selected COL3A1 mutations. Exon skipping strategies using AOs to address the nonsense and splice site mutations are described.