mutation of DDB2

Xeroderma pigmentosum (XP) is a rare autosomal recessive genodermatosis. There are eight complementation groups of XP (XP-A to G and a variant form). XP-E is one of the least common forms, and XP-E patients are generally not diagnosed until they are adults due to a later onset of skin alterations.We report a case of a 28-year-old Chinese woman with freckle-like hyperpigmented macules in a sun-exposed area who is prone to develop basal cell carcinomas. A genetic study revealed a novel homozygous c.111_112del deletion in exon 1 of the DDB2 gene. Western blotting analysis revealed that the patient lacked the expression of the wild-type mature DDB2 protein. The proband was first diagnosed with XPE on the basis of clinical findings and genetic testing. Sun protection was recommended, and the patient did not develop any skin cancers during the one-year follow-up. We identified a novel homozygous deletion in DDB2 gene in Chinese XP-E patients having unique clinical features.

着色性干皮病（Xeroderma pigmentosum, XP）是一种罕见的常染色体隐性遗传性皮肤病。目前已明确XP存在8种互补组（XP-A至XP-G及1种变异型），其中XP-E型为最罕见的亚型之一。因该型皮肤病变起病较晚，XP-E患者通常至成年阶段才获得确诊。本文报告1例28岁中国女性患者，其日晒暴露部位出现雀斑样色素沉着斑，且易并发基底细胞癌。基因检测显示，该患者的DDB2基因（DDB2 gene）外显子1存在1种新型纯合子c.111_112del缺失突变。蛋白质印迹法（Western blotting）分析结果表明，患者体内缺乏野生型成熟DDB2蛋白的表达。结合临床表现与基因检测结果，该先证者被首次确诊为XP-E型着色性干皮病。后续为患者推荐了防晒防护措施，经1年随访，患者未出现新发皮肤癌。本研究在具有独特临床特征的中国XP-E型患者中，鉴定出DDB2基因的1种新型纯合子缺失突变。