科学家发现，耳感觉毛细胞的一个基因表达突变是人类一种遗传性耳聋的原因。这个称为COMT2的基因为一种修改包括多巴胺在内大脑化学信号的酶编码。COMT2和一个此前已知基因的相似性让Bruce Beutler及其同事估计了COMT2基因的功能，他们最初把它当成了一个造成小鼠行为缺陷的突变基因。对来自有类似基因（Comt2）的小鼠细胞提取物的进一步实验证实了其功能。
这组科学家确定了拥有突变的Comt2基因的小鼠在早年显著耳聋。该病症是隐性的，即只有那些拥有两个有缺陷的基因拷贝的小鼠才会耳聋。这组科学家然后对192名聋人进行了DNA测试，结果发现数个家族的COMT2基因发生了突变。尽管目前对于这种突变还无法治疗，这个结果将帮助科学家理解神经递质如何调控内耳的毛细胞及其相关神经的生存和功能。相关论文发表在美国《国家科学院院刊》（PNAS）上。（生物谷Bioon.com）
生物谷推荐原始出处：
PNAS，doi: 10.1073/pnas.0807219105，Xin Du，Bruce Beutler
A catechol-O-methyltransferase that is essential for auditory function in mice and humans
Xin Du, Martin Schwander, Eva Marie Y. Moresco, Pia Viviani, Claudia Haller*, Michael S. Hildebrand§, Kwang Pak Lisa Tarantino, Amanda Roberts, Heather Richardson, George Koob, Hossein Najmabadi, Allen F. Ryan, Richard J. H. Smith, Ulrich Müller, and Bruce Beutler
We have identified a previously unannotated catechol-O-methyltranferase (COMT), here designated COMT2, through positional cloning of a chemically induced mutation responsible for a neurobehavioral phenotype. Mice homozygous for a missense mutation in Comt2 show vestibular impairment, profound sensorineuronal deafness, and progressive degeneration of the organ of Corti. Consistent with this phenotype, COMT2 is highly expressed in sensory hair cells of the inner ear. COMT2 enzymatic activity is significantly reduced by the missense mutation, suggesting that a defect in catecholamine catabolism underlies the auditory and vestibular phenotypes. Based on the studies in mice, we have screened DNA from human families and identified a nonsense mutation in the human ortholog of the murine Comt2 gene that causes nonsyndromic deafness. Defects in catecholamine modification by COMT have been previously implicated in the development of schizophrenia. Our studies identify a previously undescribed COMT gene and indicate an unexpected role for catecholamines in the function of auditory and vestibular sense organs.
