急激な聴力低下をきたしたUsher症候群III型症例

A Case of Usher Syndrome Type 3 with Sudden Hearing Loss

　はじめに

　網膜色素変性症に感音難聴を合併した疾患としてUsher症候群が知られている。これは遺伝性疾患の1つであり，常染色体劣性遺伝形式をとる。I〜IV型に分類されるが，I，II型に比較して進行性感音難聴を特徴とするIII型はまれである。今回，われわれはUsher症候群III型と考えられる症例を経験したので，当科におけるUsher症候群I，II型を呈示し，文献的考察を加え報告する。

Usher syndrome is characterized by bilateral sen-sorineural hearing loss with retinitis pigmentosa and has an autosomal recessive mode of inheritance. Usher syndrome has been devided into two major clinical types, type 1 and 2. The existence of the third type, which is distinguished from types 1 and 2 by the progressive nature of the hearing loss, has been suggested.

A 20-year-old man presented with progressive sensorineural hearing loss. After 6 years, he has been suffering from retinitis pigmentosa. According to the combination of visual and hearing disorders, he was diagnosed as Usher syndrome type 3.