Maeda T, Sato K, Minami H, Taguchi H, Yoshikawa K
Department of Dermatology, Osaka University School of Medicine, Japan.
Br J Dermatol. 1994 Oct;131(4):566-70. doi: 10.1111/j.1365-2133.1994.tb08562.x.
All the reported Japanese patients with group A xeroderma pigmentosum (XP) have two or three mutations at codon 116 in exon 3, codon 228 in exon 6, and the splicing acceptor site of intron 3 of XP group A complementing (XPAC) gene. A homozygote (XP39OS) with a nonsense mutation at codon 228 has less severe neurological abnormalities than patients with the splicing mutation at the acceptor site of intron 3. As homozygotes for the nonsense mutation at codon 116, which truncates a carboxyl-terminal site of XPAC protein at an early part of its zinc-finger domain, have not been reported previously, the possible severity of associated neurological abnormalities was not known. We report a group A XP patient, XP18OS, who had neurological abnormalities which were more severe than those in patients homozygous for the splicing mutation. The polymerase chain reaction product from exon 3 of the patient's XPAC gene was digested completely into three fragments by MseI restriction endonuclease. Thus, the patient was homozygous for the mutation at codon 116.
所有已报道的日本A型着色性干皮病（XP）患者在XP组A互补（XPAC）基因的第3外显子密码子116、第6外显子密码子228以及第3内含子的剪接受体位点处有两到三个突变。密码子228处有一个无义突变的纯合子（XP39OS），其神经学异常比第3内含子剪接受体位点处有剪接突变的患者要轻。由于此前尚未报道过密码子116处无义突变的纯合子，该突变在锌指结构域早期截断了XPAC蛋白的羧基末端位点，因此与之相关的神经学异常的可能严重程度尚不清楚。我们报告了一名A型XP患者，XP18OS，其神经学异常比剪接突变纯合子患者更为严重。患者XPAC基因第3外显子的聚合酶链反应产物被MseI限制性内切酶完全消化成三个片段。因此，该患者在密码子116处为突变纯合子。
