Recently, abnormal electrophoretic migration profiles of bikunin, a serum PG with a single CS chain, were detected after immunoblotting in serum from patients with specific CMD and, more specifically, from patients with “linkeropathies,” indicating that bikunin is a potential biomarker, easily detectable, for these pathologies (Bruneel et al., 2018; Haouari et al., 2020). The gene discussed is AMBP; the disease is linkeropathy.