TNXB and triple-A syndrome: Iamanaka-Yoshida and Matsumoto did not mention reference values.12 They too emphasized the role played by Tenascin-X (TN-X) in AAD and AAA, but did not go into details about the levels associated with prognosis in each disease or explain whether there is a relationship between TN-C and TN-X.12 They recommend that analysis of serum TN-C levels should be performed at the time of hospital admission and 7 days later.12