Table 1.

Classifications of Cx26 mutations linked to deafness in human patients according to data obtained from in vitro studies.

Classification	Cx 26 mutations	References
I	M1V, N14D, 30delG, 35delG, I20T, I35S, DeltaE42,, D50Y, D50N, T55N, G59A, G59V, C64S, D66H, H73R, I82M, L90P, Y136X, V153I, M163V, 167delT, P173R, D179N, R184P, L214P, 235delC, E147K, F142L	(Brown et al., 2003; Bruzzone et al., 2003; Choung et al., 2002; de Zwart-Storm et al., 2008a; de Zwart-Storm et al., 2008b; Di et al., 2005; Frei et al., 2004; Haack et al., 2006; Kudo et al., 2000; Kupka et al., 2000; Mani et al., 2008; Marziano et al., 2003; Melchionda et al., 2005; Mese et al., 2004; Oshima et al., 2003; Palmada et al., 2006; Primignani et al., 2003; Rouan et al., 2001; Thomas et al., 2004; Thonnissen et al., 2002; Yotsumoto et al., 2003; Zelante et al., 1997; Zhang et al., 2005)
II	G12R, N14K, W24X, I33T, M34 T, del 42, V37I, A40V, W44C, W44S, E47 K, R75W, R75D, R75Q, W77R, C119T, E120del, T135A, F161S, W172R, R184P	(Beahm et al., 2006; Bicego et al., 2006; Bruzzone et al., 2001; Bruzzone et al., 2003; Chen et al., 2005; D’Andrea et al., 2002; Evans et al., 1999; Gerido et al., 2007; Griffith et al., 2000; Lee et al., 2008; Mani et al., 2008; Martin et al., 1999; Marziano et al., 2003; Montgomery et al., 2004; Oshima et al., 2003; Piazza et al., 2005; Purnick et al., 2000; Richard et al., 1998; Richard et al., 2002; Rouan et al., 2001; Skerrett et al., 2004; Stong et al., 2006; Thonnissen et al., 2002; White et al., 1998)
III	T8M, G12V, N14Y, S19T, M34A, F83L, V84L, A88S, V95M, R127H, N206S,	(Arita et al., 2006; Beltramello et al., 2005; Bruzzone et al., 2003; D’Andrea et al., 2002; Lee et al., 2008; Mese et al., 2004; Mese et al., 2008; Oshima et al., 2003; Thonnissen et al., 2002; Wang et al., 2003; Zhang et al., 2005)
IV	G45E, M163L, G12R, D50N, S17F	(Gerido et al., 2007; Lee et al., 2008; Matos et al., 2008; Stong et al., 2006)
V	E114G, R143W, I128I, S183F, Q80R, V27I, V37I, I203T, c.- 15C>T, p.Met34Thr, p.Ala40Ala, p.Gly160Ser	(Batissoco et al., 2009; Choung et al., 2002; de Zwart-Storm et al., 2008a; de Zwart-Storm et al., 2008b; Kudo et al., 2000; Mese et al., 2004; Prasad et al., 2000; Wang et al., 2003)
VI	R32C, P58A, K168R, N54K, L20 5P, 465T-->A,31del14, S113P, S199F, C202F, K224Q, F142L, 313del14, 176–191 del (16), p.Lys168Arg, c.684C>A, p.Leu81Val (c.G241C), p.Met195Val (c.A583G), Q80K and P173S, S199F, T55G, D159V, 605ins46, 313del14, 355del9, 573delCA	(Antoniadi et al., 2000; Batissoco et al., 2009; Brown et al., 2003; Christiani et al., 2007; Gualandi et al., 2004; Gualandi et al., 2002; Kalay et al., 2005; Kelley et al., 1998; Kudo et al., 2000; Kupka et al., 2002; Leshinsky-Silver et al., 2005; Marlin et al., 2005; Murgia et al., 1999; Prasad et al., 2000; Primignani et al., 2007; Tamayo et al., 2009; Tekin et al., 2003; Uyguner et al., 2003; Xiao and Xie, 2004; Yuge et al., 2002)

Class I mutations are mutations preventing the formation of GJs. Class II comprises mutations that do not affect formation of GJs, but the mutated GJs display null functions. Class III refers to mutations specifically impaire the GJ-mediated biochemical coupling. Class IV consists of mutations causing a gain-of-function due to abnormal hemichannel openings. Mutations without reported functional effects on GJ functions (likely to represent polymorphism) are grouped in category V. Finally, class VI consists of mutations that have not been thoroughly studied in vitro. Detailed criteria for the classification are given in the text.