Masaru Aoyagi, Hiroshi Takenaka, Tomoo Watanabe, Masafumi Sakagami, Shin-ya Nishio, Noboru Yamanaka, Masahiko Higashikawa, Satoshi Iwasaki, Kiyofumi Gyo, Hajime Sano, Kozo Kumakawa, Akihiro Sakai, Naoto Hato, Hiromi Kojima, Shunichi Tomiyama, Shuntaro Shigihara, Kunihiro Fukushima, Yumiko Kobayashi, Kyoko Nagai, Yasuyuki Nomura, Mayumi Sugamura, Yuichi Kurono, Tetsuaki Kawase, Yasushi Naito, Maiko Miyagawa, Toshiaki Yagi, Ikuyo Miyanohara, Tsukasa Ito, Minoru Ikeda, Kotaro Ishikawa, Hiroshi Ogawa, Tetsuya Tono, Akira Ganaha, Koichi Omori, Mikio Suzuki, Satoshi Fukuda, Masako Nakai, Shin-ichi Usami, Keiji Fujihara, Toshimitsu Kobayashi, Hideichi Shinkawa, Hiroshi Moriyama, Kazuhiko Takeuchi, Hiroshi Yamashita, Yuika Sakurai, Atsushi Namba, Yasuhiro Kakazu, Takashi Nakagawa, Nobuhiko Furuya, Yuko Saito, Haruo Takahashi, Hirokazu Kawano, Norihito Takeichi, Kazunori Nishizaki, Shizuo Komune, Hiroaki Sato, Tetsuo Ikezono, Keiichi Ichimura, Kazuma Sugahara, Yukihiko Kanda, and Makito Okamoto
Mutations in SLC26A4 cause a broad phenotypic spectrum, from typical Pendred syndrome to nonsyndromic hearing loss associated with enlarged vestibular aqueduct. Identification of these mutations is important for accurate diagnosis, proper medical management and appropriate genetic counseling and requires updated information regarding spectrum, clinical characteristics and genotype-phenotype correlations, based on a large cohort. In 100 patients with bilateral enlarged vestibular aqueduct among 1511 Japanese hearing loss probands registered in our gene bank, goiter data were available for 79, of whom 15 had Pendred syndrome and 64 had nonsyndromic hearing loss. We clarified the mutation spectrum for the SLC26A4 mutations and also summarized hearing levels, progression, fluctuation and existence of genotype-phenotype correlation. SLC26A4 mutations were identified in 82 of the 100 patients (82.0%). Of the Pendred syndrome patients, 93% (14/15) were carriers, as were 77% (49/64) of the nonsyndromic hearing loss patients. Clinical characteristics of patients with SLC26A4 mutations were congenital, fluctuating and progressive hearing loss usually associated with vertigo and/or goiter. We found no genotype-phenotype correlations, indicating that, unlike in the case of GJB2 mutations, the phenotype cannot be predicted from the genotype. Our mutation analysis confirmed the importance of mutations in the SLC26A4 gene among hearing loss patients with enlarged vestibular aqueduct and revealed the mutation spectrum, essential information when performing genetic testing.