• The demonstration of structurally abnormal collagen type III produced by fibroblasts causing defective secretion, post-translational overmodification, thermal instability and/or sensitivity to proteases
• The demonstration of a mutation in the COL3A1 gene [Steinmann et al., 1993]

Determination of the serum level of procollagen type III aminopropeptide is experimental because of biological variability, confounding concomitant conditions and analytical modification of the assay necessary for the detection of low levels [Steinmann et al., 1989].