| 摘要: | 白化症是自體隱性遺傳疾病,估計其發生率約為四萬分之一。白化症可依其酪胺酸脢活性之有無,分為兩型,其中第一型白化症就是缺乏酪胺酸脢導致。在皮膚、毛髮以及眼睛中的黑色素細胞無法產生黑色素。酪胺酸的基因位於染色體11q14-21,總共有五個exons,其DNA序列已早為吾人熟悉。白化症患者因其皮膚缺乏色素保護而易導致皮膚癌,而眼睛也會因色素缺乏而有弱視及畏光的症狀。由於各人種的突變位置皆不同,且一直沒有中國人的突變資料,本研究即在此動機下,利用基因定序分析12名國人第一型白化症患者基因的突變。在24個染色體中總共偵測出21個突變點,測出率為87.5%,其中包括1個Splicing site,3個Insertion/deletion和5個Missense突變,其中Splicing site及Insertion/deletion的突變是未報告過的新突變。232insGGG這個新突變在國人的發生率極高,佔了25%之多。本研究不僅偵測出國人白化症的突變點與其他族人有不同之處,亦可提供臨床醫學在產前診斷上的輔助。
Type I oculocutaneous albinism (OCA1) is an autosomal recessive disorder, which is caused by the reduction or the absence of tyrosinase activity in melanocytes of the skin, hair and eyes. Although mutation study of OCA1 has been extensively studied in most populations worldwide, there is no systemic study of OCA1 mutation in Chinese patients. By use of single strand conformation polymorphism and direct sequencing, we had detected 21 mutant alleles out of 24 OCA1 chromosomes screened (87.5%). Detected mutant alleles include one splicing site, three insertion/deletion and five missense mutations, of which the splicing site nucleotide alteration and two each of the insertion/deletion and missense mutations are novel. The ins/del mutations accounts for about 37.5% in Chinese OCA1 alleles. The 232insGGG, one of the novel mutations, was found to be most frequent (25%) among the OCA1 alleles in Chinese. Through this study, we found that while some of the OCA mutant alleles were identified in other populations, ethnic difference still exists. |
