Ehlers-Danlos syndrome type IV: a subset of patients distinguished by low serum levels of the amino-terminal propeptide of type III procollagen.

Serum levels of procollagen type III aminopropeptide (P-III-NP), a peptide released during conversion of type III procollagen to collagen, were abnormally low in six of 10 patients with Ehlers-Danlos syndrome (EDS) type IV (arterial-ecchymotic type) and low-normal in 4. The serum P-III-NP levels correlated with the amount of type III procollagen secreted by the patients' cultured fibroblasts. Serum P-III-NP determination is a simple test that identifies a major subgroup of patients with this life-threatening, dominantly inherited connective tissue disorder and may be especially helpful in making the diagnosis in children.