Dennis Drayna of America's National Institutes of Health argued to the meeting that persistent stuttering is at least partly a matter of genes.

美国国家卫生研究院的丹尼斯。德雷纳在会上说道，持续的口吃至少一部分原因是基因问题。

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But for people who continue to stutter into adulthood, researcher Dennis Drayna of the US National Institute on Deafness and Other Communicable Disorders says stuttering can be profoundly disabling.

VOA: standard.2010.02.11

On the other side of the tent Dennis Drayna, from the National Institute on Deafness and Other Communication Disorders, in Maryland, was studying hearing.

ECONOMIST: Twin research