The causal role of this gene was supported by several lines: (I) the co-segregation of mutation with the phenotype; (II) its absence in 387 unaffected individuals of matched geographical ancestry; (III) the conservative nature of the mutation site; (IV) identification of another missense mutation of TNC in a two-generation Chinese hearing loss family; (V)TNC encoding protein, tenascin-C is a member of extracellular matrix (ECM) glycoprotein, and there have some reports about the pathological function of ECM proteins in hereditary hearing loss, such as Usherin [3] and cochlin [4]. The gene discussed is COCH; the disease is hearing loss disorder.