Nishigori C, Zghal M, Yagi T, Imamura S, Komoun M R, Takebe H
Department of Dermatology, Faculty of Medicine, Kyoto University, Japan.
Am J Hum Genet. 1993 Nov;53(5):1001-6.
Xeroderma pigmentosum (XP) patients in Tunisia who belong to the genetic complementation group A (XPA) have milder skin symptoms than do Japanese XPA patients. Such difference in the clinical features might be caused by the difference in the site of mutation in the XP A-complementing (XPAC) gene. The purpose of this study is to identify the genetic alterations in the XPAC gene in the Tunisian XPA patients and to investigate the relationship between the clinical symptoms and the genetic alterations. Three sites of mutation in the XPAC gene have been identified in the Japanese XPA patients, and about 85% of them have a G-->C point mutation at the splicing acceptor site of intron 3. We found that six (86%) of seven Tunisian XPA patients had a nonsense mutation in codon 228 in exon 6, because of a CGA-->TGA point mutation, which can be detected by the HphI RFLP. This type of mutation is the same as those found in two Japanese XPA patients with mild clinical symptoms. Milder skin symptoms in the XPA patients in Tunisia than in those in Japan, despite mostly sunny weather and the unsatisfactory sun protection in Tunisia, should be due to the difference in the mutation site.
突尼斯属于基因互补组A（XPA）的着色性干皮病（XP）患者，其皮肤症状比日本XPA患者要轻。临床特征上的这种差异可能是由XPA互补（XPAC）基因的突变位点差异所导致的。本研究的目的是确定突尼斯XPA患者XPAC基因中的遗传改变，并研究临床症状与遗传改变之间的关系。在日本XPA患者中已鉴定出XPAC基因的三个突变位点，其中约85%在第3内含子的剪接受体位点存在G→C点突变。我们发现，7例突尼斯XPA患者中有6例（86%）在外显子6的密码子228处存在无义突变，这是由于CGA→TGA点突变所致，可通过HphI限制性片段长度多态性（RFLP）检测到。这种突变类型与在两名临床症状较轻的日本XPA患者中发现的突变相同。尽管突尼斯大部分地区天气晴朗且防晒措施不佳，但突尼斯XPA患者的皮肤症状比日本患者轻，这应该是由于突变位点的差异所致。
