Study on mutation and expression of tyrosinase gene causing oculocutaneous albinisim.

我们对两例日本人的酪氨酸酶阴性眼皮白化病患者的酪氨酸酶基因进行了等位基因特异性扩增分析，结果表明他们是复合杂合，即酪氨酸酶基因的一个等位基因含有两个已知突变中的一个，另一个等位基因可能含有日本患者未知的突变。因此，我们对两例患者的酪氨酸酶基因进行了克隆和测序，确定了两个不同的点突变。一个是无义突变，密码子278CGA （Arg）到TGA (TER)，另一个是替换突变，密码子431CCA （Pro）到CTA （Leu）。然而，已经分别在一名圭亚那和一名摩洛哥犹太病人以及一名印度-巴基斯坦病人身上观察到这些相同的突变。

We examined the tyrosinase gene of two Japanese patients with tyrosinase-negative oculocutaneous albinism by allele-specific amplification analysis on two known point mutations in Japanese, and the results indicated that they were compound heterozygouts, namely, one allele of the tyrosinase gene harbored one of two known mutations and another allele probably had a mutation unknown in Japanese patients. Therefore, we have cloned and sequenced the tyrosinase gene of the two patients and identified two different point mutations. One is a nonsense mutation, codon 278CGA (Arg) to TGA (TER), and the other is a substitution mutation, codon 431CCA (Pro) to CTA (Leu). However, these same mutations have already been observed in a Guyanan and a Moroccan Jewish patient, and in an Indo-Pakistani patient, respectively.