Plasma discrimination is not yet proteoform specificity

Calling plasma proteins “dysregulated” can collapse several molecular explanations into one abundance estimate: altered synthesis, cleavage, secretion, turnover, complex formation, or modification-dependent assay response. For distinguishing Loeys-Dietz syndrome from other heritable thoracic aortic diseases, the critical evidence is whether candidate signals resolve disease-associated proteoforms rather than merely total protein abundance. The study should therefore clarify peptide uniqueness, isoform coverage, modification and processing evidence, and whether orthogonal validation recognizes the same molecular species. Without that resolution, a discriminatory protein panel may remain analytically useful, but its mechanistic interpretation—and portability across proteomic platforms—should be limited.