In collaboration with Prof. Joost Schalkwijk (U. Nijmegen, Netherlands), we found an immunoassayable TNX fragment in the sera of 146 of 151 patients with EDS; the five patients lacking serum TNX had TNXB mutations, none of which encompassed CYP21A2 (46). Here, TNXB is linked to Ehlers-Danlos syndrome.